drm/i915: Rename residual ringbuf parameters

[linux/fpc-iii.git] / drivers / gpu / drm / i915 / intel_ringbuffer.c

/*
 * Copyright © 2008-2010 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Eric Anholt <eric@anholt.net>
 *    Zou Nan hai <nanhai.zou@intel.com>
 *    Xiang Hai hao<haihao.xiang@intel.com>
 *
 */

#include <linux/log2.h>
#include <drm/drmP.h>
#include "i915_drv.h"
#include <drm/i915_drm.h>
#include "i915_trace.h"
#include "intel_drv.h"

/* Rough estimate of the typical request size, performing a flush,
 * set-context and then emitting the batch.
 */
#define LEGACY_REQUEST_SIZE 200

int __intel_ring_space(int head, int tail, int size)
{
        int space = head - tail;
        if (space <= 0)
                space += size;
        return space - I915_RING_FREE_SPACE;
}

void intel_ring_update_space(struct intel_ring *ring)
{
        if (ring->last_retired_head != -1) {
                ring->head = ring->last_retired_head;
                ring->last_retired_head = -1;
        }

        ring->space = __intel_ring_space(ring->head & HEAD_ADDR,
                                         ring->tail, ring->size);
}

static void __intel_engine_submit(struct intel_engine_cs *engine)
{
        struct intel_ring *ring = engine->buffer;

        ring->tail &= ring->size - 1;
        engine->write_tail(engine, ring->tail);
}

static int
gen2_render_ring_flush(struct drm_i915_gem_request *req,
                       u32      invalidate_domains,
                       u32      flush_domains)
{
        struct intel_ring *ring = req->ring;
        u32 cmd;
        int ret;

        cmd = MI_FLUSH;
        if (((invalidate_domains|flush_domains) & I915_GEM_DOMAIN_RENDER) == 0)
                cmd |= MI_NO_WRITE_FLUSH;

        if (invalidate_domains & I915_GEM_DOMAIN_SAMPLER)
                cmd |= MI_READ_FLUSH;

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring, cmd);
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        return 0;
}

static int
gen4_render_ring_flush(struct drm_i915_gem_request *req,
                       u32      invalidate_domains,
                       u32      flush_domains)
{
        struct intel_ring *ring = req->ring;
        u32 cmd;
        int ret;

        /*
         * read/write caches:
         *
         * I915_GEM_DOMAIN_RENDER is always invalidated, but is
         * only flushed if MI_NO_WRITE_FLUSH is unset.  On 965, it is
         * also flushed at 2d versus 3d pipeline switches.
         *
         * read-only caches:
         *
         * I915_GEM_DOMAIN_SAMPLER is flushed on pre-965 if
         * MI_READ_FLUSH is set, and is always flushed on 965.
         *
         * I915_GEM_DOMAIN_COMMAND may not exist?
         *
         * I915_GEM_DOMAIN_INSTRUCTION, which exists on 965, is
         * invalidated when MI_EXE_FLUSH is set.
         *
         * I915_GEM_DOMAIN_VERTEX, which exists on 965, is
         * invalidated with every MI_FLUSH.
         *
         * TLBs:
         *
         * On 965, TLBs associated with I915_GEM_DOMAIN_COMMAND
         * and I915_GEM_DOMAIN_CPU in are invalidated at PTE write and
         * I915_GEM_DOMAIN_RENDER and I915_GEM_DOMAIN_SAMPLER
         * are flushed at any MI_FLUSH.
         */

        cmd = MI_FLUSH;
        if (invalidate_domains) {
                cmd |= MI_EXE_FLUSH;
                if (IS_G4X(req->i915) || IS_GEN5(req->i915))
                        cmd |= MI_INVALIDATE_ISP;
        }

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring, cmd);
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        return 0;
}

/**
 * Emits a PIPE_CONTROL with a non-zero post-sync operation, for
 * implementing two workarounds on gen6.  From section 1.4.7.1
 * "PIPE_CONTROL" of the Sandy Bridge PRM volume 2 part 1:
 *
 * [DevSNB-C+{W/A}] Before any depth stall flush (including those
 * produced by non-pipelined state commands), software needs to first
 * send a PIPE_CONTROL with no bits set except Post-Sync Operation !=
 * 0.
 *
 * [Dev-SNB{W/A}]: Before a PIPE_CONTROL with Write Cache Flush Enable
 * =1, a PIPE_CONTROL with any non-zero post-sync-op is required.
 *
 * And the workaround for these two requires this workaround first:
 *
 * [Dev-SNB{W/A}]: Pipe-control with CS-stall bit set must be sent
 * BEFORE the pipe-control with a post-sync op and no write-cache
 * flushes.
 *
 * And this last workaround is tricky because of the requirements on
 * that bit.  From section 1.4.7.2.3 "Stall" of the Sandy Bridge PRM
 * volume 2 part 1:
 *
 *     "1 of the following must also be set:
 *      - Render Target Cache Flush Enable ([12] of DW1)
 *      - Depth Cache Flush Enable ([0] of DW1)
 *      - Stall at Pixel Scoreboard ([1] of DW1)
 *      - Depth Stall ([13] of DW1)
 *      - Post-Sync Operation ([13] of DW1)
 *      - Notify Enable ([8] of DW1)"
 *
 * The cache flushes require the workaround flush that triggered this
 * one, so we can't use it.  Depth stall would trigger the same.
 * Post-sync nonzero is what triggered this second workaround, so we
 * can't use that one either.  Notify enable is IRQs, which aren't
 * really our business.  That leaves only stall at scoreboard.
 */
static int
intel_emit_post_sync_nonzero_flush(struct drm_i915_gem_request *req)
{
        struct intel_ring *ring = req->ring;
        u32 scratch_addr =
                req->engine->scratch.gtt_offset + 2 * CACHELINE_BYTES;
        int ret;

        ret = intel_ring_begin(req, 6);
        if (ret)
                return ret;

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(5));
        intel_ring_emit(ring, PIPE_CONTROL_CS_STALL |
                        PIPE_CONTROL_STALL_AT_SCOREBOARD);
        intel_ring_emit(ring, scratch_addr | PIPE_CONTROL_GLOBAL_GTT);
        intel_ring_emit(ring, 0); /* low dword */
        intel_ring_emit(ring, 0); /* high dword */
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        ret = intel_ring_begin(req, 6);
        if (ret)
                return ret;

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(5));
        intel_ring_emit(ring, PIPE_CONTROL_QW_WRITE);
        intel_ring_emit(ring, scratch_addr | PIPE_CONTROL_GLOBAL_GTT);
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        return 0;
}

static int
gen6_render_ring_flush(struct drm_i915_gem_request *req,
                       u32 invalidate_domains, u32 flush_domains)
{
        struct intel_ring *ring = req->ring;
        u32 scratch_addr =
                req->engine->scratch.gtt_offset + 2 * CACHELINE_BYTES;
        u32 flags = 0;
        int ret;

        /* Force SNB workarounds for PIPE_CONTROL flushes */
        ret = intel_emit_post_sync_nonzero_flush(req);
        if (ret)
                return ret;

        /* Just flush everything.  Experiments have shown that reducing the
         * number of bits based on the write domains has little performance
         * impact.
         */
        if (flush_domains) {
                flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
                flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
                /*
                 * Ensure that any following seqno writes only happen
                 * when the render cache is indeed flushed.
                 */
                flags |= PIPE_CONTROL_CS_STALL;
        }
        if (invalidate_domains) {
                flags |= PIPE_CONTROL_TLB_INVALIDATE;
                flags |= PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_VF_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_CONST_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_STATE_CACHE_INVALIDATE;
                /*
                 * TLB invalidate requires a post-sync write.
                 */
                flags |= PIPE_CONTROL_QW_WRITE | PIPE_CONTROL_CS_STALL;
        }

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(4));
        intel_ring_emit(ring, flags);
        intel_ring_emit(ring, scratch_addr | PIPE_CONTROL_GLOBAL_GTT);
        intel_ring_emit(ring, 0);
        intel_ring_advance(ring);

        return 0;
}

static int
gen7_render_ring_cs_stall_wa(struct drm_i915_gem_request *req)
{
        struct intel_ring *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(4));
        intel_ring_emit(ring,
                        PIPE_CONTROL_CS_STALL |
                        PIPE_CONTROL_STALL_AT_SCOREBOARD);
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, 0);
        intel_ring_advance(ring);

        return 0;
}

static int
gen7_render_ring_flush(struct drm_i915_gem_request *req,
                       u32 invalidate_domains, u32 flush_domains)
{
        struct intel_ring *ring = req->ring;
        u32 scratch_addr =
                req->engine->scratch.gtt_offset + 2 * CACHELINE_BYTES;
        u32 flags = 0;
        int ret;

        /*
         * Ensure that any following seqno writes only happen when the render
         * cache is indeed flushed.
         *
         * Workaround: 4th PIPE_CONTROL command (except the ones with only
         * read-cache invalidate bits set) must have the CS_STALL bit set. We
         * don't try to be clever and just set it unconditionally.
         */
        flags |= PIPE_CONTROL_CS_STALL;

        /* Just flush everything.  Experiments have shown that reducing the
         * number of bits based on the write domains has little performance
         * impact.
         */
        if (flush_domains) {
                flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
                flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
                flags |= PIPE_CONTROL_DC_FLUSH_ENABLE;
                flags |= PIPE_CONTROL_FLUSH_ENABLE;
        }
        if (invalidate_domains) {
                flags |= PIPE_CONTROL_TLB_INVALIDATE;
                flags |= PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_VF_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_CONST_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_STATE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_MEDIA_STATE_CLEAR;
                /*
                 * TLB invalidate requires a post-sync write.
                 */
                flags |= PIPE_CONTROL_QW_WRITE;
                flags |= PIPE_CONTROL_GLOBAL_GTT_IVB;

                flags |= PIPE_CONTROL_STALL_AT_SCOREBOARD;

                /* Workaround: we must issue a pipe_control with CS-stall bit
                 * set before a pipe_control command that has the state cache
                 * invalidate bit set. */
                gen7_render_ring_cs_stall_wa(req);
        }

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(4));
        intel_ring_emit(ring, flags);
        intel_ring_emit(ring, scratch_addr);
        intel_ring_emit(ring, 0);
        intel_ring_advance(ring);

        return 0;
}

static int
gen8_emit_pipe_control(struct drm_i915_gem_request *req,
                       u32 flags, u32 scratch_addr)
{
        struct intel_ring *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 6);
        if (ret)
                return ret;

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(6));
        intel_ring_emit(ring, flags);
        intel_ring_emit(ring, scratch_addr);
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, 0);
        intel_ring_advance(ring);

        return 0;
}

static int
gen8_render_ring_flush(struct drm_i915_gem_request *req,
                       u32 invalidate_domains, u32 flush_domains)
{
        u32 scratch_addr = req->engine->scratch.gtt_offset + 2 * CACHELINE_BYTES;
        u32 flags = 0;
        int ret;

        flags |= PIPE_CONTROL_CS_STALL;

        if (flush_domains) {
                flags |= PIPE_CONTROL_RENDER_TARGET_CACHE_FLUSH;
                flags |= PIPE_CONTROL_DEPTH_CACHE_FLUSH;
                flags |= PIPE_CONTROL_DC_FLUSH_ENABLE;
                flags |= PIPE_CONTROL_FLUSH_ENABLE;
        }
        if (invalidate_domains) {
                flags |= PIPE_CONTROL_TLB_INVALIDATE;
                flags |= PIPE_CONTROL_INSTRUCTION_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_TEXTURE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_VF_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_CONST_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_STATE_CACHE_INVALIDATE;
                flags |= PIPE_CONTROL_QW_WRITE;
                flags |= PIPE_CONTROL_GLOBAL_GTT_IVB;

                /* WaCsStallBeforeStateCacheInvalidate:bdw,chv */
                ret = gen8_emit_pipe_control(req,
                                             PIPE_CONTROL_CS_STALL |
                                             PIPE_CONTROL_STALL_AT_SCOREBOARD,
                                             0);
                if (ret)
                        return ret;
        }

        return gen8_emit_pipe_control(req, flags, scratch_addr);
}

static void ring_write_tail(struct intel_engine_cs *engine,
                            u32 value)
{
        struct drm_i915_private *dev_priv = engine->i915;
        I915_WRITE_TAIL(engine, value);
}

u64 intel_engine_get_active_head(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        u64 acthd;

        if (INTEL_GEN(dev_priv) >= 8)
                acthd = I915_READ64_2x32(RING_ACTHD(engine->mmio_base),
                                         RING_ACTHD_UDW(engine->mmio_base));
        else if (INTEL_GEN(dev_priv) >= 4)
                acthd = I915_READ(RING_ACTHD(engine->mmio_base));
        else
                acthd = I915_READ(ACTHD);

        return acthd;
}

static void ring_setup_phys_status_page(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        u32 addr;

        addr = dev_priv->status_page_dmah->busaddr;
        if (INTEL_GEN(dev_priv) >= 4)
                addr |= (dev_priv->status_page_dmah->busaddr >> 28) & 0xf0;
        I915_WRITE(HWS_PGA, addr);
}

static void intel_ring_setup_status_page(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        i915_reg_t mmio;

        /* The ring status page addresses are no longer next to the rest of
         * the ring registers as of gen7.
         */
        if (IS_GEN7(dev_priv)) {
                switch (engine->id) {
                case RCS:
                        mmio = RENDER_HWS_PGA_GEN7;
                        break;
                case BCS:
                        mmio = BLT_HWS_PGA_GEN7;
                        break;
                /*
                 * VCS2 actually doesn't exist on Gen7. Only shut up
                 * gcc switch check warning
                 */
                case VCS2:
                case VCS:
                        mmio = BSD_HWS_PGA_GEN7;
                        break;
                case VECS:
                        mmio = VEBOX_HWS_PGA_GEN7;
                        break;
                }
        } else if (IS_GEN6(dev_priv)) {
                mmio = RING_HWS_PGA_GEN6(engine->mmio_base);
        } else {
                /* XXX: gen8 returns to sanity */
                mmio = RING_HWS_PGA(engine->mmio_base);
        }

        I915_WRITE(mmio, (u32)engine->status_page.gfx_addr);
        POSTING_READ(mmio);

        /*
         * Flush the TLB for this page
         *
         * FIXME: These two bits have disappeared on gen8, so a question
         * arises: do we still need this and if so how should we go about
         * invalidating the TLB?
         */
        if (IS_GEN(dev_priv, 6, 7)) {
                i915_reg_t reg = RING_INSTPM(engine->mmio_base);

                /* ring should be idle before issuing a sync flush*/
                WARN_ON((I915_READ_MODE(engine) & MODE_IDLE) == 0);

                I915_WRITE(reg,
                           _MASKED_BIT_ENABLE(INSTPM_TLB_INVALIDATE |
                                              INSTPM_SYNC_FLUSH));
                if (intel_wait_for_register(dev_priv,
                                            reg, INSTPM_SYNC_FLUSH, 0,
                                            1000))
                        DRM_ERROR("%s: wait for SyncFlush to complete for TLB invalidation timed out\n",
                                  engine->name);
        }
}

static bool stop_ring(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        if (!IS_GEN2(dev_priv)) {
                I915_WRITE_MODE(engine, _MASKED_BIT_ENABLE(STOP_RING));
                if (intel_wait_for_register(dev_priv,
                                            RING_MI_MODE(engine->mmio_base),
                                            MODE_IDLE,
                                            MODE_IDLE,
                                            1000)) {
                        DRM_ERROR("%s : timed out trying to stop ring\n",
                                  engine->name);
                        /* Sometimes we observe that the idle flag is not
                         * set even though the ring is empty. So double
                         * check before giving up.
                         */
                        if (I915_READ_HEAD(engine) != I915_READ_TAIL(engine))
                                return false;
                }
        }

        I915_WRITE_CTL(engine, 0);
        I915_WRITE_HEAD(engine, 0);
        engine->write_tail(engine, 0);

        if (!IS_GEN2(dev_priv)) {
                (void)I915_READ_CTL(engine);
                I915_WRITE_MODE(engine, _MASKED_BIT_DISABLE(STOP_RING));
        }

        return (I915_READ_HEAD(engine) & HEAD_ADDR) == 0;
}

static int init_ring_common(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        struct intel_ring *ring = engine->buffer;
        struct drm_i915_gem_object *obj = ring->obj;
        int ret = 0;

        intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);

        if (!stop_ring(engine)) {
                /* G45 ring initialization often fails to reset head to zero */
                DRM_DEBUG_KMS("%s head not reset to zero "
                              "ctl %08x head %08x tail %08x start %08x\n",
                              engine->name,
                              I915_READ_CTL(engine),
                              I915_READ_HEAD(engine),
                              I915_READ_TAIL(engine),
                              I915_READ_START(engine));

                if (!stop_ring(engine)) {
                        DRM_ERROR("failed to set %s head to zero "
                                  "ctl %08x head %08x tail %08x start %08x\n",
                                  engine->name,
                                  I915_READ_CTL(engine),
                                  I915_READ_HEAD(engine),
                                  I915_READ_TAIL(engine),
                                  I915_READ_START(engine));
                        ret = -EIO;
                        goto out;
                }
        }

        if (I915_NEED_GFX_HWS(dev_priv))
                intel_ring_setup_status_page(engine);
        else
                ring_setup_phys_status_page(engine);

        /* Enforce ordering by reading HEAD register back */
        I915_READ_HEAD(engine);

        /* Initialize the ring. This must happen _after_ we've cleared the ring
         * registers with the above sequence (the readback of the HEAD registers
         * also enforces ordering), otherwise the hw might lose the new ring
         * register values. */
        I915_WRITE_START(engine, i915_gem_obj_ggtt_offset(obj));

        /* WaClearRingBufHeadRegAtInit:ctg,elk */
        if (I915_READ_HEAD(engine))
                DRM_DEBUG("%s initialization failed [head=%08x], fudging\n",
                          engine->name, I915_READ_HEAD(engine));
        I915_WRITE_HEAD(engine, 0);
        (void)I915_READ_HEAD(engine);

        I915_WRITE_CTL(engine,
                        ((ring->size - PAGE_SIZE) & RING_NR_PAGES)
                        | RING_VALID);

        /* If the head is still not zero, the ring is dead */
        if (wait_for((I915_READ_CTL(engine) & RING_VALID) != 0 &&
                     I915_READ_START(engine) == i915_gem_obj_ggtt_offset(obj) &&
                     (I915_READ_HEAD(engine) & HEAD_ADDR) == 0, 50)) {
                DRM_ERROR("%s initialization failed "
                          "ctl %08x (valid? %d) head %08x tail %08x start %08x [expected %08lx]\n",
                          engine->name,
                          I915_READ_CTL(engine),
                          I915_READ_CTL(engine) & RING_VALID,
                          I915_READ_HEAD(engine), I915_READ_TAIL(engine),
                          I915_READ_START(engine),
                          (unsigned long)i915_gem_obj_ggtt_offset(obj));
                ret = -EIO;
                goto out;
        }

        ring->last_retired_head = -1;
        ring->head = I915_READ_HEAD(engine);
        ring->tail = I915_READ_TAIL(engine) & TAIL_ADDR;
        intel_ring_update_space(ring);

        intel_engine_init_hangcheck(engine);

out:
        intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);

        return ret;
}

void intel_fini_pipe_control(struct intel_engine_cs *engine)
{
        if (engine->scratch.obj == NULL)
                return;

        i915_gem_object_ggtt_unpin(engine->scratch.obj);
        i915_gem_object_put(engine->scratch.obj);
        engine->scratch.obj = NULL;
}

int intel_init_pipe_control(struct intel_engine_cs *engine, int size)
{
        struct drm_i915_gem_object *obj;
        int ret;

        WARN_ON(engine->scratch.obj);

        obj = i915_gem_object_create_stolen(&engine->i915->drm, size);
        if (!obj)
                obj = i915_gem_object_create(&engine->i915->drm, size);
        if (IS_ERR(obj)) {
                DRM_ERROR("Failed to allocate scratch page\n");
                ret = PTR_ERR(obj);
                goto err;
        }

        ret = i915_gem_obj_ggtt_pin(obj, 4096, PIN_HIGH);
        if (ret)
                goto err_unref;

        engine->scratch.obj = obj;
        engine->scratch.gtt_offset = i915_gem_obj_ggtt_offset(obj);
        DRM_DEBUG_DRIVER("%s pipe control offset: 0x%08x\n",
                         engine->name, engine->scratch.gtt_offset);
        return 0;

err_unref:
        i915_gem_object_put(engine->scratch.obj);
err:
        return ret;
}

static int intel_ring_workarounds_emit(struct drm_i915_gem_request *req)
{
        struct intel_ring *ring = req->ring;
        struct i915_workarounds *w = &req->i915->workarounds;
        int ret, i;

        if (w->count == 0)
                return 0;

        req->engine->gpu_caches_dirty = true;
        ret = intel_engine_flush_all_caches(req);
        if (ret)
                return ret;

        ret = intel_ring_begin(req, (w->count * 2 + 2));
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_LOAD_REGISTER_IMM(w->count));
        for (i = 0; i < w->count; i++) {
                intel_ring_emit_reg(ring, w->reg[i].addr);
                intel_ring_emit(ring, w->reg[i].value);
        }
        intel_ring_emit(ring, MI_NOOP);

        intel_ring_advance(ring);

        req->engine->gpu_caches_dirty = true;
        ret = intel_engine_flush_all_caches(req);
        if (ret)
                return ret;

        DRM_DEBUG_DRIVER("Number of Workarounds emitted: %d\n", w->count);

        return 0;
}

static int intel_rcs_ctx_init(struct drm_i915_gem_request *req)
{
        int ret;

        ret = intel_ring_workarounds_emit(req);
        if (ret != 0)
                return ret;

        ret = i915_gem_render_state_init(req);
        if (ret)
                return ret;

        return 0;
}

static int wa_add(struct drm_i915_private *dev_priv,
                  i915_reg_t addr,
                  const u32 mask, const u32 val)
{
        const u32 idx = dev_priv->workarounds.count;

        if (WARN_ON(idx >= I915_MAX_WA_REGS))
                return -ENOSPC;

        dev_priv->workarounds.reg[idx].addr = addr;
        dev_priv->workarounds.reg[idx].value = val;
        dev_priv->workarounds.reg[idx].mask = mask;

        dev_priv->workarounds.count++;

        return 0;
}

#define WA_REG(addr, mask, val) do { \
                const int r = wa_add(dev_priv, (addr), (mask), (val)); \
                if (r) \
                        return r; \
        } while (0)

#define WA_SET_BIT_MASKED(addr, mask) \
        WA_REG(addr, (mask), _MASKED_BIT_ENABLE(mask))

#define WA_CLR_BIT_MASKED(addr, mask) \
        WA_REG(addr, (mask), _MASKED_BIT_DISABLE(mask))

#define WA_SET_FIELD_MASKED(addr, mask, value) \
        WA_REG(addr, mask, _MASKED_FIELD(mask, value))

#define WA_SET_BIT(addr, mask) WA_REG(addr, mask, I915_READ(addr) | (mask))
#define WA_CLR_BIT(addr, mask) WA_REG(addr, mask, I915_READ(addr) & ~(mask))

#define WA_WRITE(addr, val) WA_REG(addr, 0xffffffff, val)

static int wa_ring_whitelist_reg(struct intel_engine_cs *engine,
                                 i915_reg_t reg)
{
        struct drm_i915_private *dev_priv = engine->i915;
        struct i915_workarounds *wa = &dev_priv->workarounds;
        const uint32_t index = wa->hw_whitelist_count[engine->id];

        if (WARN_ON(index >= RING_MAX_NONPRIV_SLOTS))
                return -EINVAL;

        WA_WRITE(RING_FORCE_TO_NONPRIV(engine->mmio_base, index),
                 i915_mmio_reg_offset(reg));
        wa->hw_whitelist_count[engine->id]++;

        return 0;
}

static int gen8_init_workarounds(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        WA_SET_BIT_MASKED(INSTPM, INSTPM_FORCE_ORDERING);

        /* WaDisableAsyncFlipPerfMode:bdw,chv */
        WA_SET_BIT_MASKED(MI_MODE, ASYNC_FLIP_PERF_DISABLE);

        /* WaDisablePartialInstShootdown:bdw,chv */
        WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN,
                          PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE);

        /* Use Force Non-Coherent whenever executing a 3D context. This is a
         * workaround for for a possible hang in the unlikely event a TLB
         * invalidation occurs during a PSD flush.
         */
        /* WaForceEnableNonCoherent:bdw,chv */
        /* WaHdcDisableFetchWhenMasked:bdw,chv */
        WA_SET_BIT_MASKED(HDC_CHICKEN0,
                          HDC_DONOT_FETCH_MEM_WHEN_MASKED |
                          HDC_FORCE_NON_COHERENT);

        /* From the Haswell PRM, Command Reference: Registers, CACHE_MODE_0:
         * "The Hierarchical Z RAW Stall Optimization allows non-overlapping
         *  polygons in the same 8x4 pixel/sample area to be processed without
         *  stalling waiting for the earlier ones to write to Hierarchical Z
         *  buffer."
         *
         * This optimization is off by default for BDW and CHV; turn it on.
         */
        WA_CLR_BIT_MASKED(CACHE_MODE_0_GEN7, HIZ_RAW_STALL_OPT_DISABLE);

        /* Wa4x4STCOptimizationDisable:bdw,chv */
        WA_SET_BIT_MASKED(CACHE_MODE_1, GEN8_4x4_STC_OPTIMIZATION_DISABLE);

        /*
         * BSpec recommends 8x4 when MSAA is used,
         * however in practice 16x4 seems fastest.
         *
         * Note that PS/WM thread counts depend on the WIZ hashing
         * disable bit, which we don't touch here, but it's good
         * to keep in mind (see 3DSTATE_PS and 3DSTATE_WM).
         */
        WA_SET_FIELD_MASKED(GEN7_GT_MODE,
                            GEN6_WIZ_HASHING_MASK,
                            GEN6_WIZ_HASHING_16x4);

        return 0;
}

static int bdw_init_workarounds(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        int ret;

        ret = gen8_init_workarounds(engine);
        if (ret)
                return ret;

        /* WaDisableThreadStallDopClockGating:bdw (pre-production) */
        WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN, STALL_DOP_GATING_DISABLE);

        /* WaDisableDopClockGating:bdw */
        WA_SET_BIT_MASKED(GEN7_ROW_CHICKEN2,
                          DOP_CLOCK_GATING_DISABLE);

        WA_SET_BIT_MASKED(HALF_SLICE_CHICKEN3,
                          GEN8_SAMPLER_POWER_BYPASS_DIS);

        WA_SET_BIT_MASKED(HDC_CHICKEN0,
                          /* WaForceContextSaveRestoreNonCoherent:bdw */
                          HDC_FORCE_CONTEXT_SAVE_RESTORE_NON_COHERENT |
                          /* WaDisableFenceDestinationToSLM:bdw (pre-prod) */
                          (IS_BDW_GT3(dev_priv) ? HDC_FENCE_DEST_SLM_DISABLE : 0));

        return 0;
}

static int chv_init_workarounds(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        int ret;

        ret = gen8_init_workarounds(engine);
        if (ret)
                return ret;

        /* WaDisableThreadStallDopClockGating:chv */
        WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN, STALL_DOP_GATING_DISABLE);

        /* Improve HiZ throughput on CHV. */
        WA_SET_BIT_MASKED(HIZ_CHICKEN, CHV_HZ_8X8_MODE_IN_1X);

        return 0;
}

static int gen9_init_workarounds(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        int ret;

        /* WaConextSwitchWithConcurrentTLBInvalidate:skl,bxt,kbl */
        I915_WRITE(GEN9_CSFE_CHICKEN1_RCS, _MASKED_BIT_ENABLE(GEN9_PREEMPT_GPGPU_SYNC_SWITCH_DISABLE));

        /* WaEnableLbsSlaRetryTimerDecrement:skl,bxt,kbl */
        I915_WRITE(BDW_SCRATCH1, I915_READ(BDW_SCRATCH1) |
                   GEN9_LBS_SLA_RETRY_TIMER_DECREMENT_ENABLE);

        /* WaDisableKillLogic:bxt,skl,kbl */
        I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) |
                   ECOCHK_DIS_TLB);

        /* WaClearFlowControlGpgpuContextSave:skl,bxt,kbl */
        /* WaDisablePartialInstShootdown:skl,bxt,kbl */
        WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN,
                          FLOW_CONTROL_ENABLE |
                          PARTIAL_INSTRUCTION_SHOOTDOWN_DISABLE);

        /* Syncing dependencies between camera and graphics:skl,bxt,kbl */
        WA_SET_BIT_MASKED(HALF_SLICE_CHICKEN3,
                          GEN9_DISABLE_OCL_OOB_SUPPRESS_LOGIC);

        /* WaDisableDgMirrorFixInHalfSliceChicken5:skl,bxt */
        if (IS_SKL_REVID(dev_priv, 0, SKL_REVID_B0) ||
            IS_BXT_REVID(dev_priv, 0, BXT_REVID_A1))
                WA_CLR_BIT_MASKED(GEN9_HALF_SLICE_CHICKEN5,
                                  GEN9_DG_MIRROR_FIX_ENABLE);

        /* WaSetDisablePixMaskCammingAndRhwoInCommonSliceChicken:skl,bxt */
        if (IS_SKL_REVID(dev_priv, 0, SKL_REVID_B0) ||
            IS_BXT_REVID(dev_priv, 0, BXT_REVID_A1)) {
                WA_SET_BIT_MASKED(GEN7_COMMON_SLICE_CHICKEN1,
                                  GEN9_RHWO_OPTIMIZATION_DISABLE);
                /*
                 * WA also requires GEN9_SLICE_COMMON_ECO_CHICKEN0[14:14] to be set
                 * but we do that in per ctx batchbuffer as there is an issue
                 * with this register not getting restored on ctx restore
                 */
        }

        /* WaEnableYV12BugFixInHalfSliceChicken7:skl,bxt,kbl */
        /* WaEnableSamplerGPGPUPreemptionSupport:skl,bxt,kbl */
        WA_SET_BIT_MASKED(GEN9_HALF_SLICE_CHICKEN7,
                          GEN9_ENABLE_YV12_BUGFIX |
                          GEN9_ENABLE_GPGPU_PREEMPTION);

        /* Wa4x4STCOptimizationDisable:skl,bxt,kbl */
        /* WaDisablePartialResolveInVc:skl,bxt,kbl */
        WA_SET_BIT_MASKED(CACHE_MODE_1, (GEN8_4x4_STC_OPTIMIZATION_DISABLE |
                                         GEN9_PARTIAL_RESOLVE_IN_VC_DISABLE));

        /* WaCcsTlbPrefetchDisable:skl,bxt,kbl */
        WA_CLR_BIT_MASKED(GEN9_HALF_SLICE_CHICKEN5,
                          GEN9_CCS_TLB_PREFETCH_ENABLE);

        /* WaDisableMaskBasedCammingInRCC:skl,bxt */
        if (IS_SKL_REVID(dev_priv, SKL_REVID_C0, SKL_REVID_C0) ||
            IS_BXT_REVID(dev_priv, 0, BXT_REVID_A1))
                WA_SET_BIT_MASKED(SLICE_ECO_CHICKEN0,
                                  PIXEL_MASK_CAMMING_DISABLE);

        /* WaForceContextSaveRestoreNonCoherent:skl,bxt,kbl */
        WA_SET_BIT_MASKED(HDC_CHICKEN0,
                          HDC_FORCE_CONTEXT_SAVE_RESTORE_NON_COHERENT |
                          HDC_FORCE_CSR_NON_COHERENT_OVR_DISABLE);

        /* WaForceEnableNonCoherent and WaDisableHDCInvalidation are
         * both tied to WaForceContextSaveRestoreNonCoherent
         * in some hsds for skl. We keep the tie for all gen9. The
         * documentation is a bit hazy and so we want to get common behaviour,
         * even though there is no clear evidence we would need both on kbl/bxt.
         * This area has been source of system hangs so we play it safe
         * and mimic the skl regardless of what bspec says.
         *
         * Use Force Non-Coherent whenever executing a 3D context. This
         * is a workaround for a possible hang in the unlikely event
         * a TLB invalidation occurs during a PSD flush.
         */

        /* WaForceEnableNonCoherent:skl,bxt,kbl */
        WA_SET_BIT_MASKED(HDC_CHICKEN0,
                          HDC_FORCE_NON_COHERENT);

        /* WaDisableHDCInvalidation:skl,bxt,kbl */
        I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) |
                   BDW_DISABLE_HDC_INVALIDATION);

        /* WaDisableSamplerPowerBypassForSOPingPong:skl,bxt,kbl */
        if (IS_SKYLAKE(dev_priv) ||
            IS_KABYLAKE(dev_priv) ||
            IS_BXT_REVID(dev_priv, 0, BXT_REVID_B0))
                WA_SET_BIT_MASKED(HALF_SLICE_CHICKEN3,
                                  GEN8_SAMPLER_POWER_BYPASS_DIS);

        /* WaDisableSTUnitPowerOptimization:skl,bxt,kbl */
        WA_SET_BIT_MASKED(HALF_SLICE_CHICKEN2, GEN8_ST_PO_DISABLE);

        /* WaOCLCoherentLineFlush:skl,bxt,kbl */
        I915_WRITE(GEN8_L3SQCREG4, (I915_READ(GEN8_L3SQCREG4) |
                                    GEN8_LQSC_FLUSH_COHERENT_LINES));

        /* WaVFEStateAfterPipeControlwithMediaStateClear:skl,bxt */
        ret = wa_ring_whitelist_reg(engine, GEN9_CTX_PREEMPT_REG);
        if (ret)
                return ret;

        /* WaEnablePreemptionGranularityControlByUMD:skl,bxt,kbl */
        ret= wa_ring_whitelist_reg(engine, GEN8_CS_CHICKEN1);
        if (ret)
                return ret;

        /* WaAllowUMDToModifyHDCChicken1:skl,bxt,kbl */
        ret = wa_ring_whitelist_reg(engine, GEN8_HDC_CHICKEN1);
        if (ret)
                return ret;

        return 0;
}

static int skl_tune_iz_hashing(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        u8 vals[3] = { 0, 0, 0 };
        unsigned int i;

        for (i = 0; i < 3; i++) {
                u8 ss;

                /*
                 * Only consider slices where one, and only one, subslice has 7
                 * EUs
                 */
                if (!is_power_of_2(dev_priv->info.subslice_7eu[i]))
                        continue;

                /*
                 * subslice_7eu[i] != 0 (because of the check above) and
                 * ss_max == 4 (maximum number of subslices possible per slice)
                 *
                 * ->    0 <= ss <= 3;
                 */
                ss = ffs(dev_priv->info.subslice_7eu[i]) - 1;
                vals[i] = 3 - ss;
        }

        if (vals[0] == 0 && vals[1] == 0 && vals[2] == 0)
                return 0;

        /* Tune IZ hashing. See intel_device_info_runtime_init() */
        WA_SET_FIELD_MASKED(GEN7_GT_MODE,
                            GEN9_IZ_HASHING_MASK(2) |
                            GEN9_IZ_HASHING_MASK(1) |
                            GEN9_IZ_HASHING_MASK(0),
                            GEN9_IZ_HASHING(2, vals[2]) |
                            GEN9_IZ_HASHING(1, vals[1]) |
                            GEN9_IZ_HASHING(0, vals[0]));

        return 0;
}

static int skl_init_workarounds(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        int ret;

        ret = gen9_init_workarounds(engine);
        if (ret)
                return ret;

        /*
         * Actual WA is to disable percontext preemption granularity control
         * until D0 which is the default case so this is equivalent to
         * !WaDisablePerCtxtPreemptionGranularityControl:skl
         */
        if (IS_SKL_REVID(dev_priv, SKL_REVID_E0, REVID_FOREVER)) {
                I915_WRITE(GEN7_FF_SLICE_CS_CHICKEN1,
                           _MASKED_BIT_ENABLE(GEN9_FFSC_PERCTX_PREEMPT_CTRL));
        }

        if (IS_SKL_REVID(dev_priv, 0, SKL_REVID_E0)) {
                /* WaDisableChickenBitTSGBarrierAckForFFSliceCS:skl */
                I915_WRITE(FF_SLICE_CS_CHICKEN2,
                           _MASKED_BIT_ENABLE(GEN9_TSG_BARRIER_ACK_DISABLE));
        }

        /* GEN8_L3SQCREG4 has a dependency with WA batch so any new changes
         * involving this register should also be added to WA batch as required.
         */
        if (IS_SKL_REVID(dev_priv, 0, SKL_REVID_E0))
                /* WaDisableLSQCROPERFforOCL:skl */
                I915_WRITE(GEN8_L3SQCREG4, I915_READ(GEN8_L3SQCREG4) |
                           GEN8_LQSC_RO_PERF_DIS);

        /* WaEnableGapsTsvCreditFix:skl */
        if (IS_SKL_REVID(dev_priv, SKL_REVID_C0, REVID_FOREVER)) {
                I915_WRITE(GEN8_GARBCNTL, (I915_READ(GEN8_GARBCNTL) |
                                           GEN9_GAPS_TSV_CREDIT_DISABLE));
        }

        /* WaDisablePowerCompilerClockGating:skl */
        if (IS_SKL_REVID(dev_priv, SKL_REVID_B0, SKL_REVID_B0))
                WA_SET_BIT_MASKED(HIZ_CHICKEN,
                                  BDW_HIZ_POWER_COMPILER_CLOCK_GATING_DISABLE);

        /* WaBarrierPerformanceFixDisable:skl */
        if (IS_SKL_REVID(dev_priv, SKL_REVID_C0, SKL_REVID_D0))
                WA_SET_BIT_MASKED(HDC_CHICKEN0,
                                  HDC_FENCE_DEST_SLM_DISABLE |
                                  HDC_BARRIER_PERFORMANCE_DISABLE);

        /* WaDisableSbeCacheDispatchPortSharing:skl */
        if (IS_SKL_REVID(dev_priv, 0, SKL_REVID_F0))
                WA_SET_BIT_MASKED(
                        GEN7_HALF_SLICE_CHICKEN1,
                        GEN7_SBE_SS_CACHE_DISPATCH_PORT_SHARING_DISABLE);

        /* WaDisableGafsUnitClkGating:skl */
        WA_SET_BIT(GEN7_UCGCTL4, GEN8_EU_GAUNIT_CLOCK_GATE_DISABLE);

        /* WaInPlaceDecompressionHang:skl */
        if (IS_SKL_REVID(dev_priv, SKL_REVID_H0, REVID_FOREVER))
                WA_SET_BIT(GEN9_GAMT_ECO_REG_RW_IA,
                           GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);

        /* WaDisableLSQCROPERFforOCL:skl */
        ret = wa_ring_whitelist_reg(engine, GEN8_L3SQCREG4);
        if (ret)
                return ret;

        return skl_tune_iz_hashing(engine);
}

static int bxt_init_workarounds(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        int ret;

        ret = gen9_init_workarounds(engine);
        if (ret)
                return ret;

        /* WaStoreMultiplePTEenable:bxt */
        /* This is a requirement according to Hardware specification */
        if (IS_BXT_REVID(dev_priv, 0, BXT_REVID_A1))
                I915_WRITE(TILECTL, I915_READ(TILECTL) | TILECTL_TLBPF);

        /* WaSetClckGatingDisableMedia:bxt */
        if (IS_BXT_REVID(dev_priv, 0, BXT_REVID_A1)) {
                I915_WRITE(GEN7_MISCCPCTL, (I915_READ(GEN7_MISCCPCTL) &
                                            ~GEN8_DOP_CLOCK_GATE_MEDIA_ENABLE));
        }

        /* WaDisableThreadStallDopClockGating:bxt */
        WA_SET_BIT_MASKED(GEN8_ROW_CHICKEN,
                          STALL_DOP_GATING_DISABLE);

        /* WaDisablePooledEuLoadBalancingFix:bxt */
        if (IS_BXT_REVID(dev_priv, BXT_REVID_B0, REVID_FOREVER)) {
                WA_SET_BIT_MASKED(FF_SLICE_CS_CHICKEN2,
                                  GEN9_POOLED_EU_LOAD_BALANCING_FIX_DISABLE);
        }

        /* WaDisableSbeCacheDispatchPortSharing:bxt */
        if (IS_BXT_REVID(dev_priv, 0, BXT_REVID_B0)) {
                WA_SET_BIT_MASKED(
                        GEN7_HALF_SLICE_CHICKEN1,
                        GEN7_SBE_SS_CACHE_DISPATCH_PORT_SHARING_DISABLE);
        }

        /* WaDisableObjectLevelPreemptionForTrifanOrPolygon:bxt */
        /* WaDisableObjectLevelPreemptionForInstancedDraw:bxt */
        /* WaDisableObjectLevelPreemtionForInstanceId:bxt */
        /* WaDisableLSQCROPERFforOCL:bxt */
        if (IS_BXT_REVID(dev_priv, 0, BXT_REVID_A1)) {
                ret = wa_ring_whitelist_reg(engine, GEN9_CS_DEBUG_MODE1);
                if (ret)
                        return ret;

                ret = wa_ring_whitelist_reg(engine, GEN8_L3SQCREG4);
                if (ret)
                        return ret;
        }

        /* WaProgramL3SqcReg1DefaultForPerf:bxt */
        if (IS_BXT_REVID(dev_priv, BXT_REVID_B0, REVID_FOREVER))
                I915_WRITE(GEN8_L3SQCREG1, L3_GENERAL_PRIO_CREDITS(62) |
                                           L3_HIGH_PRIO_CREDITS(2));

        /* WaInsertDummyPushConstPs:bxt */
        if (IS_BXT_REVID(dev_priv, 0, BXT_REVID_B0))
                WA_SET_BIT_MASKED(COMMON_SLICE_CHICKEN2,
                                  GEN8_SBE_DISABLE_REPLAY_BUF_OPTIMIZATION);

        /* WaInPlaceDecompressionHang:bxt */
        if (IS_BXT_REVID(dev_priv, BXT_REVID_C0, REVID_FOREVER))
                WA_SET_BIT(GEN9_GAMT_ECO_REG_RW_IA,
                           GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);

        return 0;
}

static int kbl_init_workarounds(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        int ret;

        ret = gen9_init_workarounds(engine);
        if (ret)
                return ret;

        /* WaEnableGapsTsvCreditFix:kbl */
        I915_WRITE(GEN8_GARBCNTL, (I915_READ(GEN8_GARBCNTL) |
                                   GEN9_GAPS_TSV_CREDIT_DISABLE));

        /* WaDisableDynamicCreditSharing:kbl */
        if (IS_KBL_REVID(dev_priv, 0, KBL_REVID_B0))
                WA_SET_BIT(GAMT_CHKN_BIT_REG,
                           GAMT_CHKN_DISABLE_DYNAMIC_CREDIT_SHARING);

        /* WaDisableFenceDestinationToSLM:kbl (pre-prod) */
        if (IS_KBL_REVID(dev_priv, KBL_REVID_A0, KBL_REVID_A0))
                WA_SET_BIT_MASKED(HDC_CHICKEN0,
                                  HDC_FENCE_DEST_SLM_DISABLE);

        /* GEN8_L3SQCREG4 has a dependency with WA batch so any new changes
         * involving this register should also be added to WA batch as required.
         */
        if (IS_KBL_REVID(dev_priv, 0, KBL_REVID_E0))
                /* WaDisableLSQCROPERFforOCL:kbl */
                I915_WRITE(GEN8_L3SQCREG4, I915_READ(GEN8_L3SQCREG4) |
                           GEN8_LQSC_RO_PERF_DIS);

        /* WaInsertDummyPushConstPs:kbl */
        if (IS_KBL_REVID(dev_priv, 0, KBL_REVID_B0))
                WA_SET_BIT_MASKED(COMMON_SLICE_CHICKEN2,
                                  GEN8_SBE_DISABLE_REPLAY_BUF_OPTIMIZATION);

        /* WaDisableGafsUnitClkGating:kbl */
        WA_SET_BIT(GEN7_UCGCTL4, GEN8_EU_GAUNIT_CLOCK_GATE_DISABLE);

        /* WaDisableSbeCacheDispatchPortSharing:kbl */
        WA_SET_BIT_MASKED(
                GEN7_HALF_SLICE_CHICKEN1,
                GEN7_SBE_SS_CACHE_DISPATCH_PORT_SHARING_DISABLE);

        /* WaInPlaceDecompressionHang:kbl */
        WA_SET_BIT(GEN9_GAMT_ECO_REG_RW_IA,
                   GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);

        /* WaDisableLSQCROPERFforOCL:kbl */
        ret = wa_ring_whitelist_reg(engine, GEN8_L3SQCREG4);
        if (ret)
                return ret;

        return 0;
}

int init_workarounds_ring(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        WARN_ON(engine->id != RCS);

        dev_priv->workarounds.count = 0;
        dev_priv->workarounds.hw_whitelist_count[RCS] = 0;

        if (IS_BROADWELL(dev_priv))
                return bdw_init_workarounds(engine);

        if (IS_CHERRYVIEW(dev_priv))
                return chv_init_workarounds(engine);

        if (IS_SKYLAKE(dev_priv))
                return skl_init_workarounds(engine);

        if (IS_BROXTON(dev_priv))
                return bxt_init_workarounds(engine);

        if (IS_KABYLAKE(dev_priv))
                return kbl_init_workarounds(engine);

        return 0;
}

static int init_render_ring(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        int ret = init_ring_common(engine);
        if (ret)
                return ret;

        /* WaTimedSingleVertexDispatch:cl,bw,ctg,elk,ilk,snb */
        if (IS_GEN(dev_priv, 4, 6))
                I915_WRITE(MI_MODE, _MASKED_BIT_ENABLE(VS_TIMER_DISPATCH));

        /* We need to disable the AsyncFlip performance optimisations in order
         * to use MI_WAIT_FOR_EVENT within the CS. It should already be
         * programmed to '1' on all products.
         *
         * WaDisableAsyncFlipPerfMode:snb,ivb,hsw,vlv
         */
        if (IS_GEN(dev_priv, 6, 7))
                I915_WRITE(MI_MODE, _MASKED_BIT_ENABLE(ASYNC_FLIP_PERF_DISABLE));

        /* Required for the hardware to program scanline values for waiting */
        /* WaEnableFlushTlbInvalidationMode:snb */
        if (IS_GEN6(dev_priv))
                I915_WRITE(GFX_MODE,
                           _MASKED_BIT_ENABLE(GFX_TLB_INVALIDATE_EXPLICIT));

        /* WaBCSVCSTlbInvalidationMode:ivb,vlv,hsw */
        if (IS_GEN7(dev_priv))
                I915_WRITE(GFX_MODE_GEN7,
                           _MASKED_BIT_ENABLE(GFX_TLB_INVALIDATE_EXPLICIT) |
                           _MASKED_BIT_ENABLE(GFX_REPLAY_MODE));

        if (IS_GEN6(dev_priv)) {
                /* From the Sandybridge PRM, volume 1 part 3, page 24:
                 * "If this bit is set, STCunit will have LRA as replacement
                 *  policy. [...] This bit must be reset.  LRA replacement
                 *  policy is not supported."
                 */
                I915_WRITE(CACHE_MODE_0,
                           _MASKED_BIT_DISABLE(CM0_STC_EVICT_DISABLE_LRA_SNB));
        }

        if (IS_GEN(dev_priv, 6, 7))
                I915_WRITE(INSTPM, _MASKED_BIT_ENABLE(INSTPM_FORCE_ORDERING));

        if (INTEL_INFO(dev_priv)->gen >= 6)
                I915_WRITE_IMR(engine, ~engine->irq_keep_mask);

        return init_workarounds_ring(engine);
}

static void render_ring_cleanup(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        if (dev_priv->semaphore_obj) {
                i915_gem_object_ggtt_unpin(dev_priv->semaphore_obj);
                i915_gem_object_put(dev_priv->semaphore_obj);
                dev_priv->semaphore_obj = NULL;
        }

        intel_fini_pipe_control(engine);
}

static int gen8_rcs_signal(struct drm_i915_gem_request *signaller_req,
                           unsigned int num_dwords)
{
#define MBOX_UPDATE_DWORDS 8
        struct intel_ring *signaller = signaller_req->ring;
        struct drm_i915_private *dev_priv = signaller_req->i915;
        struct intel_engine_cs *waiter;
        enum intel_engine_id id;
        int ret, num_rings;

        num_rings = hweight32(INTEL_INFO(dev_priv)->ring_mask);
        num_dwords += (num_rings-1) * MBOX_UPDATE_DWORDS;
#undef MBOX_UPDATE_DWORDS

        ret = intel_ring_begin(signaller_req, num_dwords);
        if (ret)
                return ret;

        for_each_engine_id(waiter, dev_priv, id) {
                u64 gtt_offset =
                        signaller_req->engine->semaphore.signal_ggtt[id];
                if (gtt_offset == MI_SEMAPHORE_SYNC_INVALID)
                        continue;

                intel_ring_emit(signaller, GFX_OP_PIPE_CONTROL(6));
                intel_ring_emit(signaller,
                                PIPE_CONTROL_GLOBAL_GTT_IVB |
                                PIPE_CONTROL_QW_WRITE |
                                PIPE_CONTROL_CS_STALL);
                intel_ring_emit(signaller, lower_32_bits(gtt_offset));
                intel_ring_emit(signaller, upper_32_bits(gtt_offset));
                intel_ring_emit(signaller, signaller_req->fence.seqno);
                intel_ring_emit(signaller, 0);
                intel_ring_emit(signaller,
                                MI_SEMAPHORE_SIGNAL |
                                MI_SEMAPHORE_TARGET(waiter->hw_id));
                intel_ring_emit(signaller, 0);
        }

        return 0;
}

static int gen8_xcs_signal(struct drm_i915_gem_request *signaller_req,
                           unsigned int num_dwords)
{
#define MBOX_UPDATE_DWORDS 6
        struct intel_ring *signaller = signaller_req->ring;
        struct drm_i915_private *dev_priv = signaller_req->i915;
        struct intel_engine_cs *waiter;
        enum intel_engine_id id;
        int ret, num_rings;

        num_rings = hweight32(INTEL_INFO(dev_priv)->ring_mask);
        num_dwords += (num_rings-1) * MBOX_UPDATE_DWORDS;
#undef MBOX_UPDATE_DWORDS

        ret = intel_ring_begin(signaller_req, num_dwords);
        if (ret)
                return ret;

        for_each_engine_id(waiter, dev_priv, id) {
                u64 gtt_offset =
                        signaller_req->engine->semaphore.signal_ggtt[id];
                if (gtt_offset == MI_SEMAPHORE_SYNC_INVALID)
                        continue;

                intel_ring_emit(signaller,
                                (MI_FLUSH_DW + 1) | MI_FLUSH_DW_OP_STOREDW);
                intel_ring_emit(signaller,
                                lower_32_bits(gtt_offset) |
                                MI_FLUSH_DW_USE_GTT);
                intel_ring_emit(signaller, upper_32_bits(gtt_offset));
                intel_ring_emit(signaller, signaller_req->fence.seqno);
                intel_ring_emit(signaller,
                                MI_SEMAPHORE_SIGNAL |
                                MI_SEMAPHORE_TARGET(waiter->hw_id));
                intel_ring_emit(signaller, 0);
        }

        return 0;
}

static int gen6_signal(struct drm_i915_gem_request *signaller_req,
                       unsigned int num_dwords)
{
        struct intel_ring *signaller = signaller_req->ring;
        struct drm_i915_private *dev_priv = signaller_req->i915;
        struct intel_engine_cs *useless;
        enum intel_engine_id id;
        int ret, num_rings;

#define MBOX_UPDATE_DWORDS 3
        num_rings = hweight32(INTEL_INFO(dev_priv)->ring_mask);
        num_dwords += round_up((num_rings-1) * MBOX_UPDATE_DWORDS, 2);
#undef MBOX_UPDATE_DWORDS

        ret = intel_ring_begin(signaller_req, num_dwords);
        if (ret)
                return ret;

        for_each_engine_id(useless, dev_priv, id) {
                i915_reg_t mbox_reg =
                        signaller_req->engine->semaphore.mbox.signal[id];

                if (i915_mmio_reg_valid(mbox_reg)) {
                        intel_ring_emit(signaller, MI_LOAD_REGISTER_IMM(1));
                        intel_ring_emit_reg(signaller, mbox_reg);
                        intel_ring_emit(signaller, signaller_req->fence.seqno);
                }
        }

        /* If num_dwords was rounded, make sure the tail pointer is correct */
        if (num_rings % 2 == 0)
                intel_ring_emit(signaller, MI_NOOP);

        return 0;
}

/**
 * gen6_add_request - Update the semaphore mailbox registers
 *
 * @request - request to write to the ring
 *
 * Update the mailbox registers in the *other* rings with the current seqno.
 * This acts like a signal in the canonical semaphore.
 */
static int
gen6_add_request(struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *engine = req->engine;
        struct intel_ring *ring = req->ring;
        int ret;

        if (engine->semaphore.signal)
                ret = engine->semaphore.signal(req, 4);
        else
                ret = intel_ring_begin(req, 4);

        if (ret)
                return ret;

        intel_ring_emit(ring, MI_STORE_DWORD_INDEX);
        intel_ring_emit(ring, I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
        intel_ring_emit(ring, req->fence.seqno);
        intel_ring_emit(ring, MI_USER_INTERRUPT);
        __intel_engine_submit(engine);

        return 0;
}

static int
gen8_render_add_request(struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *engine = req->engine;
        struct intel_ring *ring = req->ring;
        int ret;

        if (engine->semaphore.signal)
                ret = engine->semaphore.signal(req, 8);
        else
                ret = intel_ring_begin(req, 8);
        if (ret)
                return ret;

        intel_ring_emit(ring, GFX_OP_PIPE_CONTROL(6));
        intel_ring_emit(ring, (PIPE_CONTROL_GLOBAL_GTT_IVB |
                               PIPE_CONTROL_CS_STALL |
                               PIPE_CONTROL_QW_WRITE));
        intel_ring_emit(ring, intel_hws_seqno_address(engine));
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, i915_gem_request_get_seqno(req));
        /* We're thrashing one dword of HWS. */
        intel_ring_emit(ring, 0);
        intel_ring_emit(ring, MI_USER_INTERRUPT);
        intel_ring_emit(ring, MI_NOOP);
        __intel_engine_submit(engine);

        return 0;
}

static inline bool i915_gem_has_seqno_wrapped(struct drm_i915_private *dev_priv,
                                              u32 seqno)
{
        return dev_priv->last_seqno < seqno;
}

/**
 * intel_ring_sync - sync the waiter to the signaller on seqno
 *
 * @waiter - ring that is waiting
 * @signaller - ring which has, or will signal
 * @seqno - seqno which the waiter will block on
 */

static int
gen8_ring_sync(struct drm_i915_gem_request *waiter_req,
               struct intel_engine_cs *signaller,
               u32 seqno)
{
        struct intel_ring *waiter = waiter_req->ring;
        struct drm_i915_private *dev_priv = waiter_req->i915;
        u64 offset = GEN8_WAIT_OFFSET(waiter_req->engine, signaller->id);
        struct i915_hw_ppgtt *ppgtt;
        int ret;

        ret = intel_ring_begin(waiter_req, 4);
        if (ret)
                return ret;

        intel_ring_emit(waiter, MI_SEMAPHORE_WAIT |
                                MI_SEMAPHORE_GLOBAL_GTT |
                                MI_SEMAPHORE_SAD_GTE_SDD);
        intel_ring_emit(waiter, seqno);
        intel_ring_emit(waiter, lower_32_bits(offset));
        intel_ring_emit(waiter, upper_32_bits(offset));
        intel_ring_advance(waiter);

        /* When the !RCS engines idle waiting upon a semaphore, they lose their
         * pagetables and we must reload them before executing the batch.
         * We do this on the i915_switch_context() following the wait and
         * before the dispatch.
         */
        ppgtt = waiter_req->ctx->ppgtt;
        if (ppgtt && waiter_req->engine->id != RCS)
                ppgtt->pd_dirty_rings |= intel_engine_flag(waiter_req->engine);
        return 0;
}

static int
gen6_ring_sync(struct drm_i915_gem_request *waiter_req,
               struct intel_engine_cs *signaller,
               u32 seqno)
{
        struct intel_ring *waiter = waiter_req->ring;
        u32 dw1 = MI_SEMAPHORE_MBOX |
                  MI_SEMAPHORE_COMPARE |
                  MI_SEMAPHORE_REGISTER;
        u32 wait_mbox = signaller->semaphore.mbox.wait[waiter_req->engine->id];
        int ret;

        /* Throughout all of the GEM code, seqno passed implies our current
         * seqno is >= the last seqno executed. However for hardware the
         * comparison is strictly greater than.
         */
        seqno -= 1;

        WARN_ON(wait_mbox == MI_SEMAPHORE_SYNC_INVALID);

        ret = intel_ring_begin(waiter_req, 4);
        if (ret)
                return ret;

        /* If seqno wrap happened, omit the wait with no-ops */
        if (likely(!i915_gem_has_seqno_wrapped(waiter_req->i915, seqno))) {
                intel_ring_emit(waiter, dw1 | wait_mbox);
                intel_ring_emit(waiter, seqno);
                intel_ring_emit(waiter, 0);
                intel_ring_emit(waiter, MI_NOOP);
        } else {
                intel_ring_emit(waiter, MI_NOOP);
                intel_ring_emit(waiter, MI_NOOP);
                intel_ring_emit(waiter, MI_NOOP);
                intel_ring_emit(waiter, MI_NOOP);
        }
        intel_ring_advance(waiter);

        return 0;
}

static void
gen5_seqno_barrier(struct intel_engine_cs *engine)
{
        /* MI_STORE are internally buffered by the GPU and not flushed
         * either by MI_FLUSH or SyncFlush or any other combination of
         * MI commands.
         *
         * "Only the submission of the store operation is guaranteed.
         * The write result will be complete (coherent) some time later
         * (this is practically a finite period but there is no guaranteed
         * latency)."
         *
         * Empirically, we observe that we need a delay of at least 75us to
         * be sure that the seqno write is visible by the CPU.
         */
        usleep_range(125, 250);
}

static void
gen6_seqno_barrier(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        /* Workaround to force correct ordering between irq and seqno writes on
         * ivb (and maybe also on snb) by reading from a CS register (like
         * ACTHD) before reading the status page.
         *
         * Note that this effectively stalls the read by the time it takes to
         * do a memory transaction, which more or less ensures that the write
         * from the GPU has sufficient time to invalidate the CPU cacheline.
         * Alternatively we could delay the interrupt from the CS ring to give
         * the write time to land, but that would incur a delay after every
         * batch i.e. much more frequent than a delay when waiting for the
         * interrupt (with the same net latency).
         *
         * Also note that to prevent whole machine hangs on gen7, we have to
         * take the spinlock to guard against concurrent cacheline access.
         */
        spin_lock_irq(&dev_priv->uncore.lock);
        POSTING_READ_FW(RING_ACTHD(engine->mmio_base));
        spin_unlock_irq(&dev_priv->uncore.lock);
}

static void
gen5_irq_enable(struct intel_engine_cs *engine)
{
        gen5_enable_gt_irq(engine->i915, engine->irq_enable_mask);
}

static void
gen5_irq_disable(struct intel_engine_cs *engine)
{
        gen5_disable_gt_irq(engine->i915, engine->irq_enable_mask);
}

static void
i9xx_irq_enable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        dev_priv->irq_mask &= ~engine->irq_enable_mask;
        I915_WRITE(IMR, dev_priv->irq_mask);
        POSTING_READ_FW(RING_IMR(engine->mmio_base));
}

static void
i9xx_irq_disable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        dev_priv->irq_mask |= engine->irq_enable_mask;
        I915_WRITE(IMR, dev_priv->irq_mask);
}

static void
i8xx_irq_enable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        dev_priv->irq_mask &= ~engine->irq_enable_mask;
        I915_WRITE16(IMR, dev_priv->irq_mask);
        POSTING_READ16(RING_IMR(engine->mmio_base));
}

static void
i8xx_irq_disable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        dev_priv->irq_mask |= engine->irq_enable_mask;
        I915_WRITE16(IMR, dev_priv->irq_mask);
}

static int
bsd_ring_flush(struct drm_i915_gem_request *req,
               u32     invalidate_domains,
               u32     flush_domains)
{
        struct intel_ring *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_FLUSH);
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);
        return 0;
}

static int
i9xx_add_request(struct drm_i915_gem_request *req)
{
        struct intel_ring *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_STORE_DWORD_INDEX);
        intel_ring_emit(ring, I915_GEM_HWS_INDEX << MI_STORE_DWORD_INDEX_SHIFT);
        intel_ring_emit(ring, req->fence.seqno);
        intel_ring_emit(ring, MI_USER_INTERRUPT);
        __intel_engine_submit(req->engine);

        return 0;
}

static void
gen6_irq_enable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        I915_WRITE_IMR(engine,
                       ~(engine->irq_enable_mask |
                         engine->irq_keep_mask));
        gen5_enable_gt_irq(dev_priv, engine->irq_enable_mask);
}

static void
gen6_irq_disable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        I915_WRITE_IMR(engine, ~engine->irq_keep_mask);
        gen5_disable_gt_irq(dev_priv, engine->irq_enable_mask);
}

static void
hsw_vebox_irq_enable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        I915_WRITE_IMR(engine, ~engine->irq_enable_mask);
        gen6_enable_pm_irq(dev_priv, engine->irq_enable_mask);
}

static void
hsw_vebox_irq_disable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        I915_WRITE_IMR(engine, ~0);
        gen6_disable_pm_irq(dev_priv, engine->irq_enable_mask);
}

static void
gen8_irq_enable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        I915_WRITE_IMR(engine,
                       ~(engine->irq_enable_mask |
                         engine->irq_keep_mask));
        POSTING_READ_FW(RING_IMR(engine->mmio_base));
}

static void
gen8_irq_disable(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        I915_WRITE_IMR(engine, ~engine->irq_keep_mask);
}

static int
i965_dispatch_execbuffer(struct drm_i915_gem_request *req,
                         u64 offset, u32 length,
                         unsigned dispatch_flags)
{
        struct intel_ring *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring,
                        MI_BATCH_BUFFER_START |
                        MI_BATCH_GTT |
                        (dispatch_flags & I915_DISPATCH_SECURE ?
                         0 : MI_BATCH_NON_SECURE_I965));
        intel_ring_emit(ring, offset);
        intel_ring_advance(ring);

        return 0;
}

/* Just userspace ABI convention to limit the wa batch bo to a resonable size */
#define I830_BATCH_LIMIT (256*1024)
#define I830_TLB_ENTRIES (2)
#define I830_WA_SIZE max(I830_TLB_ENTRIES*4096, I830_BATCH_LIMIT)
static int
i830_dispatch_execbuffer(struct drm_i915_gem_request *req,
                         u64 offset, u32 len,
                         unsigned dispatch_flags)
{
        struct intel_ring *ring = req->ring;
        u32 cs_offset = req->engine->scratch.gtt_offset;
        int ret;

        ret = intel_ring_begin(req, 6);
        if (ret)
                return ret;

        /* Evict the invalid PTE TLBs */
        intel_ring_emit(ring, COLOR_BLT_CMD | BLT_WRITE_RGBA);
        intel_ring_emit(ring, BLT_DEPTH_32 | BLT_ROP_COLOR_COPY | 4096);
        intel_ring_emit(ring, I830_TLB_ENTRIES << 16 | 4); /* load each page */
        intel_ring_emit(ring, cs_offset);
        intel_ring_emit(ring, 0xdeadbeef);
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        if ((dispatch_flags & I915_DISPATCH_PINNED) == 0) {
                if (len > I830_BATCH_LIMIT)
                        return -ENOSPC;

                ret = intel_ring_begin(req, 6 + 2);
                if (ret)
                        return ret;

                /* Blit the batch (which has now all relocs applied) to the
                 * stable batch scratch bo area (so that the CS never
                 * stumbles over its tlb invalidation bug) ...
                 */
                intel_ring_emit(ring, SRC_COPY_BLT_CMD | BLT_WRITE_RGBA);
                intel_ring_emit(ring,
                                BLT_DEPTH_32 | BLT_ROP_SRC_COPY | 4096);
                intel_ring_emit(ring, DIV_ROUND_UP(len, 4096) << 16 | 4096);
                intel_ring_emit(ring, cs_offset);
                intel_ring_emit(ring, 4096);
                intel_ring_emit(ring, offset);

                intel_ring_emit(ring, MI_FLUSH);
                intel_ring_emit(ring, MI_NOOP);
                intel_ring_advance(ring);

                /* ... and execute it. */
                offset = cs_offset;
        }

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_BATCH_BUFFER_START | MI_BATCH_GTT);
        intel_ring_emit(ring, offset | (dispatch_flags & I915_DISPATCH_SECURE ?
                                        0 : MI_BATCH_NON_SECURE));
        intel_ring_advance(ring);

        return 0;
}

static int
i915_dispatch_execbuffer(struct drm_i915_gem_request *req,
                         u64 offset, u32 len,
                         unsigned dispatch_flags)
{
        struct intel_ring *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring, MI_BATCH_BUFFER_START | MI_BATCH_GTT);
        intel_ring_emit(ring, offset | (dispatch_flags & I915_DISPATCH_SECURE ?
                                        0 : MI_BATCH_NON_SECURE));
        intel_ring_advance(ring);

        return 0;
}

static void cleanup_phys_status_page(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        if (!dev_priv->status_page_dmah)
                return;

        drm_pci_free(&dev_priv->drm, dev_priv->status_page_dmah);
        engine->status_page.page_addr = NULL;
}

static void cleanup_status_page(struct intel_engine_cs *engine)
{
        struct drm_i915_gem_object *obj;

        obj = engine->status_page.obj;
        if (obj == NULL)
                return;

        kunmap(sg_page(obj->pages->sgl));
        i915_gem_object_ggtt_unpin(obj);
        i915_gem_object_put(obj);
        engine->status_page.obj = NULL;
}

static int init_status_page(struct intel_engine_cs *engine)
{
        struct drm_i915_gem_object *obj = engine->status_page.obj;

        if (obj == NULL) {
                unsigned flags;
                int ret;

                obj = i915_gem_object_create(&engine->i915->drm, 4096);
                if (IS_ERR(obj)) {
                        DRM_ERROR("Failed to allocate status page\n");
                        return PTR_ERR(obj);
                }

                ret = i915_gem_object_set_cache_level(obj, I915_CACHE_LLC);
                if (ret)
                        goto err_unref;

                flags = 0;
                if (!HAS_LLC(engine->i915))
                        /* On g33, we cannot place HWS above 256MiB, so
                         * restrict its pinning to the low mappable arena.
                         * Though this restriction is not documented for
                         * gen4, gen5, or byt, they also behave similarly
                         * and hang if the HWS is placed at the top of the
                         * GTT. To generalise, it appears that all !llc
                         * platforms have issues with us placing the HWS
                         * above the mappable region (even though we never
                         * actualy map it).
                         */
                        flags |= PIN_MAPPABLE;
                ret = i915_gem_obj_ggtt_pin(obj, 4096, flags);
                if (ret) {
err_unref:
                        i915_gem_object_put(obj);
                        return ret;
                }

                engine->status_page.obj = obj;
        }

        engine->status_page.gfx_addr = i915_gem_obj_ggtt_offset(obj);
        engine->status_page.page_addr = kmap(sg_page(obj->pages->sgl));
        memset(engine->status_page.page_addr, 0, PAGE_SIZE);

        DRM_DEBUG_DRIVER("%s hws offset: 0x%08x\n",
                        engine->name, engine->status_page.gfx_addr);

        return 0;
}

static int init_phys_status_page(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        if (!dev_priv->status_page_dmah) {
                dev_priv->status_page_dmah =
                        drm_pci_alloc(&dev_priv->drm, PAGE_SIZE, PAGE_SIZE);
                if (!dev_priv->status_page_dmah)
                        return -ENOMEM;
        }

        engine->status_page.page_addr = dev_priv->status_page_dmah->vaddr;
        memset(engine->status_page.page_addr, 0, PAGE_SIZE);

        return 0;
}

void intel_unpin_ring(struct intel_ring *ring)
{
        GEM_BUG_ON(!ring->vma);
        GEM_BUG_ON(!ring->vaddr);

        if (HAS_LLC(ring->obj->base.dev) && !ring->obj->stolen)
                i915_gem_object_unpin_map(ring->obj);
        else
                i915_vma_unpin_iomap(ring->vma);
        ring->vaddr = NULL;

        i915_gem_object_ggtt_unpin(ring->obj);
        ring->vma = NULL;
}

int intel_pin_and_map_ring(struct drm_i915_private *dev_priv,
                           struct intel_ring *ring)
{
        struct drm_i915_gem_object *obj = ring->obj;
        /* Ring wraparound at offset 0 sometimes hangs. No idea why. */
        unsigned flags = PIN_OFFSET_BIAS | 4096;
        void *addr;
        int ret;

        if (HAS_LLC(dev_priv) && !obj->stolen) {
                ret = i915_gem_obj_ggtt_pin(obj, PAGE_SIZE, flags);
                if (ret)
                        return ret;

                ret = i915_gem_object_set_to_cpu_domain(obj, true);
                if (ret)
                        goto err_unpin;

                addr = i915_gem_object_pin_map(obj);
                if (IS_ERR(addr)) {
                        ret = PTR_ERR(addr);
                        goto err_unpin;
                }
        } else {
                ret = i915_gem_obj_ggtt_pin(obj, PAGE_SIZE,
                                            flags | PIN_MAPPABLE);
                if (ret)
                        return ret;

                ret = i915_gem_object_set_to_gtt_domain(obj, true);
                if (ret)
                        goto err_unpin;

                /* Access through the GTT requires the device to be awake. */
                assert_rpm_wakelock_held(dev_priv);

                addr = (void __force *)
                        i915_vma_pin_iomap(i915_gem_obj_to_ggtt(obj));
                if (IS_ERR(addr)) {
                        ret = PTR_ERR(addr);
                        goto err_unpin;
                }
        }

        ring->vaddr = addr;
        ring->vma = i915_gem_obj_to_ggtt(obj);
        return 0;

err_unpin:
        i915_gem_object_ggtt_unpin(obj);
        return ret;
}

static void intel_destroy_ringbuffer_obj(struct intel_ring *ring)
{
        i915_gem_object_put(ring->obj);
        ring->obj = NULL;
}

static int intel_alloc_ringbuffer_obj(struct drm_device *dev,
                                      struct intel_ring *ring)
{
        struct drm_i915_gem_object *obj;

        obj = NULL;
        if (!HAS_LLC(dev))
                obj = i915_gem_object_create_stolen(dev, ring->size);
        if (obj == NULL)
                obj = i915_gem_object_create(dev, ring->size);
        if (IS_ERR(obj))
                return PTR_ERR(obj);

        /* mark ring buffers as read-only from GPU side by default */
        obj->gt_ro = 1;

        ring->obj = obj;

        return 0;
}

struct intel_ring *
intel_engine_create_ring(struct intel_engine_cs *engine, int size)
{
        struct intel_ring *ring;
        int ret;

        ring = kzalloc(sizeof(*ring), GFP_KERNEL);
        if (ring == NULL) {
                DRM_DEBUG_DRIVER("Failed to allocate ringbuffer %s\n",
                                 engine->name);
                return ERR_PTR(-ENOMEM);
        }

        ring->engine = engine;
        list_add(&ring->link, &engine->buffers);

        ring->size = size;
        /* Workaround an erratum on the i830 which causes a hang if
         * the TAIL pointer points to within the last 2 cachelines
         * of the buffer.
         */
        ring->effective_size = size;
        if (IS_I830(engine->i915) || IS_845G(engine->i915))
                ring->effective_size -= 2 * CACHELINE_BYTES;

        ring->last_retired_head = -1;
        intel_ring_update_space(ring);

        ret = intel_alloc_ringbuffer_obj(&engine->i915->drm, ring);
        if (ret) {
                DRM_DEBUG_DRIVER("Failed to allocate ringbuffer %s: %d\n",
                                 engine->name, ret);
                list_del(&ring->link);
                kfree(ring);
                return ERR_PTR(ret);
        }

        return ring;
}

void
intel_ring_free(struct intel_ring *ring)
{
        intel_destroy_ringbuffer_obj(ring);
        list_del(&ring->link);
        kfree(ring);
}

static int intel_ring_context_pin(struct i915_gem_context *ctx,
                                  struct intel_engine_cs *engine)
{
        struct intel_context *ce = &ctx->engine[engine->id];
        int ret;

        lockdep_assert_held(&ctx->i915->drm.struct_mutex);

        if (ce->pin_count++)
                return 0;

        if (ce->state) {
                ret = i915_gem_obj_ggtt_pin(ce->state, ctx->ggtt_alignment, 0);
                if (ret)
                        goto error;
        }

        /* The kernel context is only used as a placeholder for flushing the
         * active context. It is never used for submitting user rendering and
         * as such never requires the golden render context, and so we can skip
         * emitting it when we switch to the kernel context. This is required
         * as during eviction we cannot allocate and pin the renderstate in
         * order to initialise the context.
         */
        if (ctx == ctx->i915->kernel_context)
                ce->initialised = true;

        i915_gem_context_get(ctx);
        return 0;

error:
        ce->pin_count = 0;
        return ret;
}

static void intel_ring_context_unpin(struct i915_gem_context *ctx,
                                     struct intel_engine_cs *engine)
{
        struct intel_context *ce = &ctx->engine[engine->id];

        lockdep_assert_held(&ctx->i915->drm.struct_mutex);

        if (--ce->pin_count)
                return;

        if (ce->state)
                i915_gem_object_ggtt_unpin(ce->state);

        i915_gem_context_put(ctx);
}

static int intel_init_ring_buffer(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        struct intel_ring *ring;
        int ret;

        WARN_ON(engine->buffer);

        intel_engine_setup_common(engine);

        memset(engine->semaphore.sync_seqno, 0,
               sizeof(engine->semaphore.sync_seqno));

        ret = intel_engine_init_common(engine);
        if (ret)
                goto error;

        /* We may need to do things with the shrinker which
         * require us to immediately switch back to the default
         * context. This can cause a problem as pinning the
         * default context also requires GTT space which may not
         * be available. To avoid this we always pin the default
         * context.
         */
        ret = intel_ring_context_pin(dev_priv->kernel_context, engine);
        if (ret)
                goto error;

        ring = intel_engine_create_ring(engine, 32 * PAGE_SIZE);
        if (IS_ERR(ring)) {
                ret = PTR_ERR(ring);
                goto error;
        }
        engine->buffer = ring;

        if (I915_NEED_GFX_HWS(dev_priv)) {
                ret = init_status_page(engine);
                if (ret)
                        goto error;
        } else {
                WARN_ON(engine->id != RCS);
                ret = init_phys_status_page(engine);
                if (ret)
                        goto error;
        }

        ret = intel_pin_and_map_ring(dev_priv, ring);
        if (ret) {
                DRM_ERROR("Failed to pin and map ringbuffer %s: %d\n",
                                engine->name, ret);
                intel_destroy_ringbuffer_obj(ring);
                goto error;
        }

        return 0;

error:
        intel_engine_cleanup(engine);
        return ret;
}

void intel_engine_cleanup(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv;

        if (!intel_engine_initialized(engine))
                return;

        dev_priv = engine->i915;

        if (engine->buffer) {
                intel_engine_stop(engine);
                WARN_ON(!IS_GEN2(dev_priv) && (I915_READ_MODE(engine) & MODE_IDLE) == 0);

                intel_unpin_ring(engine->buffer);
                intel_ring_free(engine->buffer);
                engine->buffer = NULL;
        }

        if (engine->cleanup)
                engine->cleanup(engine);

        if (I915_NEED_GFX_HWS(dev_priv)) {
                cleanup_status_page(engine);
        } else {
                WARN_ON(engine->id != RCS);
                cleanup_phys_status_page(engine);
        }

        intel_engine_cleanup_cmd_parser(engine);
        i915_gem_batch_pool_fini(&engine->batch_pool);
        intel_engine_fini_breadcrumbs(engine);

        intel_ring_context_unpin(dev_priv->kernel_context, engine);

        engine->i915 = NULL;
}

int intel_engine_idle(struct intel_engine_cs *engine)
{
        struct drm_i915_gem_request *req;

        /* Wait upon the last request to be completed */
        if (list_empty(&engine->request_list))
                return 0;

        req = list_entry(engine->request_list.prev,
                         struct drm_i915_gem_request,
                         list);

        /* Make sure we do not trigger any retires */
        return __i915_wait_request(req,
                                   req->i915->mm.interruptible,
                                   NULL, NULL);
}

int intel_ring_alloc_request_extras(struct drm_i915_gem_request *request)
{
        int ret;

        /* Flush enough space to reduce the likelihood of waiting after
         * we start building the request - in which case we will just
         * have to repeat work.
         */
        request->reserved_space += LEGACY_REQUEST_SIZE;

        request->ring = request->engine->buffer;

        ret = intel_ring_begin(request, 0);
        if (ret)
                return ret;

        request->reserved_space -= LEGACY_REQUEST_SIZE;
        return 0;
}

static int wait_for_space(struct drm_i915_gem_request *req, int bytes)
{
        struct intel_ring *ring = req->ring;
        struct intel_engine_cs *engine = req->engine;
        struct drm_i915_gem_request *target;

        intel_ring_update_space(ring);
        if (ring->space >= bytes)
                return 0;

        /*
         * Space is reserved in the ringbuffer for finalising the request,
         * as that cannot be allowed to fail. During request finalisation,
         * reserved_space is set to 0 to stop the overallocation and the
         * assumption is that then we never need to wait (which has the
         * risk of failing with EINTR).
         *
         * See also i915_gem_request_alloc() and i915_add_request().
         */
        GEM_BUG_ON(!req->reserved_space);

        list_for_each_entry(target, &engine->request_list, list) {
                unsigned space;

                /*
                 * The request queue is per-engine, so can contain requests
                 * from multiple ringbuffers. Here, we must ignore any that
                 * aren't from the ringbuffer we're considering.
                 */
                if (target->ring != ring)
                        continue;

                /* Would completion of this request free enough space? */
                space = __intel_ring_space(target->postfix, ring->tail,
                                           ring->size);
                if (space >= bytes)
                        break;
        }

        if (WARN_ON(&target->list == &engine->request_list))
                return -ENOSPC;

        return i915_wait_request(target);
}

int intel_ring_begin(struct drm_i915_gem_request *req, int num_dwords)
{
        struct intel_ring *ring = req->ring;
        int remain_actual = ring->size - ring->tail;
        int remain_usable = ring->effective_size - ring->tail;
        int bytes = num_dwords * sizeof(u32);
        int total_bytes, wait_bytes;
        bool need_wrap = false;

        total_bytes = bytes + req->reserved_space;

        if (unlikely(bytes > remain_usable)) {
                /*
                 * Not enough space for the basic request. So need to flush
                 * out the remainder and then wait for base + reserved.
                 */
                wait_bytes = remain_actual + total_bytes;
                need_wrap = true;
        } else if (unlikely(total_bytes > remain_usable)) {
                /*
                 * The base request will fit but the reserved space
                 * falls off the end. So we don't need an immediate wrap
                 * and only need to effectively wait for the reserved
                 * size space from the start of ringbuffer.
                 */
                wait_bytes = remain_actual + req->reserved_space;
        } else {
                /* No wrapping required, just waiting. */
                wait_bytes = total_bytes;
        }

        if (wait_bytes > ring->space) {
                int ret = wait_for_space(req, wait_bytes);
                if (unlikely(ret))
                        return ret;

                intel_ring_update_space(ring);
                if (unlikely(ring->space < wait_bytes))
                        return -EAGAIN;
        }

        if (unlikely(need_wrap)) {
                GEM_BUG_ON(remain_actual > ring->space);
                GEM_BUG_ON(ring->tail + remain_actual > ring->size);

                /* Fill the tail with MI_NOOP */
                memset(ring->vaddr + ring->tail, 0, remain_actual);
                ring->tail = 0;
                ring->space -= remain_actual;
        }

        ring->space -= bytes;
        GEM_BUG_ON(ring->space < 0);
        return 0;
}

/* Align the ring tail to a cacheline boundary */
int intel_ring_cacheline_align(struct drm_i915_gem_request *req)
{
        struct intel_ring *ring = req->ring;
        int num_dwords =
                (ring->tail & (CACHELINE_BYTES - 1)) / sizeof(uint32_t);
        int ret;

        if (num_dwords == 0)
                return 0;

        num_dwords = CACHELINE_BYTES / sizeof(uint32_t) - num_dwords;
        ret = intel_ring_begin(req, num_dwords);
        if (ret)
                return ret;

        while (num_dwords--)
                intel_ring_emit(ring, MI_NOOP);

        intel_ring_advance(ring);

        return 0;
}

void intel_engine_init_seqno(struct intel_engine_cs *engine, u32 seqno)
{
        struct drm_i915_private *dev_priv = engine->i915;

        /* Our semaphore implementation is strictly monotonic (i.e. we proceed
         * so long as the semaphore value in the register/page is greater
         * than the sync value), so whenever we reset the seqno,
         * so long as we reset the tracking semaphore value to 0, it will
         * always be before the next request's seqno. If we don't reset
         * the semaphore value, then when the seqno moves backwards all
         * future waits will complete instantly (causing rendering corruption).
         */
        if (IS_GEN6(dev_priv) || IS_GEN7(dev_priv)) {
                I915_WRITE(RING_SYNC_0(engine->mmio_base), 0);
                I915_WRITE(RING_SYNC_1(engine->mmio_base), 0);
                if (HAS_VEBOX(dev_priv))
                        I915_WRITE(RING_SYNC_2(engine->mmio_base), 0);
        }
        if (dev_priv->semaphore_obj) {
                struct drm_i915_gem_object *obj = dev_priv->semaphore_obj;
                struct page *page = i915_gem_object_get_dirty_page(obj, 0);
                void *semaphores = kmap(page);
                memset(semaphores + GEN8_SEMAPHORE_OFFSET(engine->id, 0),
                       0, I915_NUM_ENGINES * gen8_semaphore_seqno_size);
                kunmap(page);
        }
        memset(engine->semaphore.sync_seqno, 0,
               sizeof(engine->semaphore.sync_seqno));

        intel_write_status_page(engine, I915_GEM_HWS_INDEX, seqno);
        if (engine->irq_seqno_barrier)
                engine->irq_seqno_barrier(engine);
        engine->last_submitted_seqno = seqno;

        engine->hangcheck.seqno = seqno;

        /* After manually advancing the seqno, fake the interrupt in case
         * there are any waiters for that seqno.
         */
        rcu_read_lock();
        intel_engine_wakeup(engine);
        rcu_read_unlock();
}

static void gen6_bsd_ring_write_tail(struct intel_engine_cs *engine,
                                     u32 value)
{
        struct drm_i915_private *dev_priv = engine->i915;

        intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);

       /* Every tail move must follow the sequence below */

        /* Disable notification that the ring is IDLE. The GT
         * will then assume that it is busy and bring it out of rc6.
         */
        I915_WRITE_FW(GEN6_BSD_SLEEP_PSMI_CONTROL,
                      _MASKED_BIT_ENABLE(GEN6_BSD_SLEEP_MSG_DISABLE));

        /* Clear the context id. Here be magic! */
        I915_WRITE64_FW(GEN6_BSD_RNCID, 0x0);

        /* Wait for the ring not to be idle, i.e. for it to wake up. */
        if (intel_wait_for_register_fw(dev_priv,
                                       GEN6_BSD_SLEEP_PSMI_CONTROL,
                                       GEN6_BSD_SLEEP_INDICATOR,
                                       0,
                                       50))
                DRM_ERROR("timed out waiting for the BSD ring to wake up\n");

        /* Now that the ring is fully powered up, update the tail */
        I915_WRITE_FW(RING_TAIL(engine->mmio_base), value);
        POSTING_READ_FW(RING_TAIL(engine->mmio_base));

        /* Let the ring send IDLE messages to the GT again,
         * and so let it sleep to conserve power when idle.
         */
        I915_WRITE_FW(GEN6_BSD_SLEEP_PSMI_CONTROL,
                      _MASKED_BIT_DISABLE(GEN6_BSD_SLEEP_MSG_DISABLE));

        intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
}

static int gen6_bsd_ring_flush(struct drm_i915_gem_request *req,
                               u32 invalidate, u32 flush)
{
        struct intel_ring *ring = req->ring;
        uint32_t cmd;
        int ret;

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        cmd = MI_FLUSH_DW;
        if (INTEL_GEN(req->i915) >= 8)
                cmd += 1;

        /* We always require a command barrier so that subsequent
         * commands, such as breadcrumb interrupts, are strictly ordered
         * wrt the contents of the write cache being flushed to memory
         * (and thus being coherent from the CPU).
         */
        cmd |= MI_FLUSH_DW_STORE_INDEX | MI_FLUSH_DW_OP_STOREDW;

        /*
         * Bspec vol 1c.5 - video engine command streamer:
         * "If ENABLED, all TLBs will be invalidated once the flush
         * operation is complete. This bit is only valid when the
         * Post-Sync Operation field is a value of 1h or 3h."
         */
        if (invalidate & I915_GEM_GPU_DOMAINS)
                cmd |= MI_INVALIDATE_TLB | MI_INVALIDATE_BSD;

        intel_ring_emit(ring, cmd);
        intel_ring_emit(ring, I915_GEM_HWS_SCRATCH_ADDR | MI_FLUSH_DW_USE_GTT);
        if (INTEL_GEN(req->i915) >= 8) {
                intel_ring_emit(ring, 0); /* upper addr */
                intel_ring_emit(ring, 0); /* value */
        } else  {
                intel_ring_emit(ring, 0);
                intel_ring_emit(ring, MI_NOOP);
        }
        intel_ring_advance(ring);
        return 0;
}

static int
gen8_ring_dispatch_execbuffer(struct drm_i915_gem_request *req,
                              u64 offset, u32 len,
                              unsigned dispatch_flags)
{
        struct intel_ring *ring = req->ring;
        bool ppgtt = USES_PPGTT(req->i915) &&
                        !(dispatch_flags & I915_DISPATCH_SECURE);
        int ret;

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        /* FIXME(BDW): Address space and security selectors. */
        intel_ring_emit(ring, MI_BATCH_BUFFER_START_GEN8 | (ppgtt<<8) |
                        (dispatch_flags & I915_DISPATCH_RS ?
                         MI_BATCH_RESOURCE_STREAMER : 0));
        intel_ring_emit(ring, lower_32_bits(offset));
        intel_ring_emit(ring, upper_32_bits(offset));
        intel_ring_emit(ring, MI_NOOP);
        intel_ring_advance(ring);

        return 0;
}

static int
hsw_ring_dispatch_execbuffer(struct drm_i915_gem_request *req,
                             u64 offset, u32 len,
                             unsigned dispatch_flags)
{
        struct intel_ring *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring,
                        MI_BATCH_BUFFER_START |
                        (dispatch_flags & I915_DISPATCH_SECURE ?
                         0 : MI_BATCH_PPGTT_HSW | MI_BATCH_NON_SECURE_HSW) |
                        (dispatch_flags & I915_DISPATCH_RS ?
                         MI_BATCH_RESOURCE_STREAMER : 0));
        /* bit0-7 is the length on GEN6+ */
        intel_ring_emit(ring, offset);
        intel_ring_advance(ring);

        return 0;
}

static int
gen6_ring_dispatch_execbuffer(struct drm_i915_gem_request *req,
                              u64 offset, u32 len,
                              unsigned dispatch_flags)
{
        struct intel_ring *ring = req->ring;
        int ret;

        ret = intel_ring_begin(req, 2);
        if (ret)
                return ret;

        intel_ring_emit(ring,
                        MI_BATCH_BUFFER_START |
                        (dispatch_flags & I915_DISPATCH_SECURE ?
                         0 : MI_BATCH_NON_SECURE_I965));
        /* bit0-7 is the length on GEN6+ */
        intel_ring_emit(ring, offset);
        intel_ring_advance(ring);

        return 0;
}

/* Blitter support (SandyBridge+) */

static int gen6_ring_flush(struct drm_i915_gem_request *req,
                           u32 invalidate, u32 flush)
{
        struct intel_ring *ring = req->ring;
        uint32_t cmd;
        int ret;

        ret = intel_ring_begin(req, 4);
        if (ret)
                return ret;

        cmd = MI_FLUSH_DW;
        if (INTEL_GEN(req->i915) >= 8)
                cmd += 1;

        /* We always require a command barrier so that subsequent
         * commands, such as breadcrumb interrupts, are strictly ordered
         * wrt the contents of the write cache being flushed to memory
         * (and thus being coherent from the CPU).
         */
        cmd |= MI_FLUSH_DW_STORE_INDEX | MI_FLUSH_DW_OP_STOREDW;

        /*
         * Bspec vol 1c.3 - blitter engine command streamer:
         * "If ENABLED, all TLBs will be invalidated once the flush
         * operation is complete. This bit is only valid when the
         * Post-Sync Operation field is a value of 1h or 3h."
         */
        if (invalidate & I915_GEM_DOMAIN_RENDER)
                cmd |= MI_INVALIDATE_TLB;
        intel_ring_emit(ring, cmd);
        intel_ring_emit(ring,
                        I915_GEM_HWS_SCRATCH_ADDR | MI_FLUSH_DW_USE_GTT);
        if (INTEL_GEN(req->i915) >= 8) {
                intel_ring_emit(ring, 0); /* upper addr */
                intel_ring_emit(ring, 0); /* value */
        } else  {
                intel_ring_emit(ring, 0);
                intel_ring_emit(ring, MI_NOOP);
        }
        intel_ring_advance(ring);

        return 0;
}

static void intel_ring_init_semaphores(struct drm_i915_private *dev_priv,
                                       struct intel_engine_cs *engine)
{
        struct drm_i915_gem_object *obj;
        int ret, i;

        if (!i915.semaphores)
                return;

        if (INTEL_GEN(dev_priv) >= 8 && !dev_priv->semaphore_obj) {
                obj = i915_gem_object_create(&dev_priv->drm, 4096);
                if (IS_ERR(obj)) {
                        DRM_ERROR("Failed to allocate semaphore bo. Disabling semaphores\n");
                        i915.semaphores = 0;
                } else {
                        i915_gem_object_set_cache_level(obj, I915_CACHE_LLC);
                        ret = i915_gem_obj_ggtt_pin(obj, 0, PIN_NONBLOCK);
                        if (ret != 0) {
                                i915_gem_object_put(obj);
                                DRM_ERROR("Failed to pin semaphore bo. Disabling semaphores\n");
                                i915.semaphores = 0;
                        } else {
                                dev_priv->semaphore_obj = obj;
                        }
                }
        }

        if (!i915.semaphores)
                return;

        if (INTEL_GEN(dev_priv) >= 8) {
                u64 offset = i915_gem_obj_ggtt_offset(dev_priv->semaphore_obj);

                engine->semaphore.sync_to = gen8_ring_sync;
                engine->semaphore.signal = gen8_xcs_signal;

                for (i = 0; i < I915_NUM_ENGINES; i++) {
                        u64 ring_offset;

                        if (i != engine->id)
                                ring_offset = offset + GEN8_SEMAPHORE_OFFSET(engine->id, i);
                        else
                                ring_offset = MI_SEMAPHORE_SYNC_INVALID;

                        engine->semaphore.signal_ggtt[i] = ring_offset;
                }
        } else if (INTEL_GEN(dev_priv) >= 6) {
                engine->semaphore.sync_to = gen6_ring_sync;
                engine->semaphore.signal = gen6_signal;

                /*
                 * The current semaphore is only applied on pre-gen8
                 * platform.  And there is no VCS2 ring on the pre-gen8
                 * platform. So the semaphore between RCS and VCS2 is
                 * initialized as INVALID.  Gen8 will initialize the
                 * sema between VCS2 and RCS later.
                 */
                for (i = 0; i < I915_NUM_ENGINES; i++) {
                        static const struct {
                                u32 wait_mbox;
                                i915_reg_t mbox_reg;
                        } sem_data[I915_NUM_ENGINES][I915_NUM_ENGINES] = {
                                [RCS] = {
                                        [VCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_RV,  .mbox_reg = GEN6_VRSYNC },
                                        [BCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_RB,  .mbox_reg = GEN6_BRSYNC },
                                        [VECS] = { .wait_mbox = MI_SEMAPHORE_SYNC_RVE, .mbox_reg = GEN6_VERSYNC },
                                },
                                [VCS] = {
                                        [RCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VR,  .mbox_reg = GEN6_RVSYNC },
                                        [BCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VB,  .mbox_reg = GEN6_BVSYNC },
                                        [VECS] = { .wait_mbox = MI_SEMAPHORE_SYNC_VVE, .mbox_reg = GEN6_VEVSYNC },
                                },
                                [BCS] = {
                                        [RCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_BR,  .mbox_reg = GEN6_RBSYNC },
                                        [VCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_BV,  .mbox_reg = GEN6_VBSYNC },
                                        [VECS] = { .wait_mbox = MI_SEMAPHORE_SYNC_BVE, .mbox_reg = GEN6_VEBSYNC },
                                },
                                [VECS] = {
                                        [RCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VER, .mbox_reg = GEN6_RVESYNC },
                                        [VCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VEV, .mbox_reg = GEN6_VVESYNC },
                                        [BCS] =  { .wait_mbox = MI_SEMAPHORE_SYNC_VEB, .mbox_reg = GEN6_BVESYNC },
                                },
                        };
                        u32 wait_mbox;
                        i915_reg_t mbox_reg;

                        if (i == engine->id || i == VCS2) {
                                wait_mbox = MI_SEMAPHORE_SYNC_INVALID;
                                mbox_reg = GEN6_NOSYNC;
                        } else {
                                wait_mbox = sem_data[engine->id][i].wait_mbox;
                                mbox_reg = sem_data[engine->id][i].mbox_reg;
                        }

                        engine->semaphore.mbox.wait[i] = wait_mbox;
                        engine->semaphore.mbox.signal[i] = mbox_reg;
                }
        }
}

static void intel_ring_init_irq(struct drm_i915_private *dev_priv,
                                struct intel_engine_cs *engine)
{
        engine->irq_enable_mask = GT_RENDER_USER_INTERRUPT << engine->irq_shift;

        if (INTEL_GEN(dev_priv) >= 8) {
                engine->irq_enable = gen8_irq_enable;
                engine->irq_disable = gen8_irq_disable;
                engine->irq_seqno_barrier = gen6_seqno_barrier;
        } else if (INTEL_GEN(dev_priv) >= 6) {
                engine->irq_enable = gen6_irq_enable;
                engine->irq_disable = gen6_irq_disable;
                engine->irq_seqno_barrier = gen6_seqno_barrier;
        } else if (INTEL_GEN(dev_priv) >= 5) {
                engine->irq_enable = gen5_irq_enable;
                engine->irq_disable = gen5_irq_disable;
                engine->irq_seqno_barrier = gen5_seqno_barrier;
        } else if (INTEL_GEN(dev_priv) >= 3) {
                engine->irq_enable = i9xx_irq_enable;
                engine->irq_disable = i9xx_irq_disable;
        } else {
                engine->irq_enable = i8xx_irq_enable;
                engine->irq_disable = i8xx_irq_disable;
        }
}

static void intel_ring_default_vfuncs(struct drm_i915_private *dev_priv,
                                      struct intel_engine_cs *engine)
{
        engine->init_hw = init_ring_common;
        engine->write_tail = ring_write_tail;

        engine->add_request = i9xx_add_request;
        if (INTEL_GEN(dev_priv) >= 6)
                engine->add_request = gen6_add_request;

        if (INTEL_GEN(dev_priv) >= 8)
                engine->dispatch_execbuffer = gen8_ring_dispatch_execbuffer;
        else if (INTEL_GEN(dev_priv) >= 6)
                engine->dispatch_execbuffer = gen6_ring_dispatch_execbuffer;
        else if (INTEL_GEN(dev_priv) >= 4)
                engine->dispatch_execbuffer = i965_dispatch_execbuffer;
        else if (IS_I830(dev_priv) || IS_845G(dev_priv))
                engine->dispatch_execbuffer = i830_dispatch_execbuffer;
        else
                engine->dispatch_execbuffer = i915_dispatch_execbuffer;

        intel_ring_init_irq(dev_priv, engine);
        intel_ring_init_semaphores(dev_priv, engine);
}

int intel_init_render_ring_buffer(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;
        int ret;

        intel_ring_default_vfuncs(dev_priv, engine);

        if (HAS_L3_DPF(dev_priv))
                engine->irq_keep_mask = GT_RENDER_L3_PARITY_ERROR_INTERRUPT;

        if (INTEL_GEN(dev_priv) >= 8) {
                engine->init_context = intel_rcs_ctx_init;
                engine->add_request = gen8_render_add_request;
                engine->flush = gen8_render_ring_flush;
                if (i915.semaphores)
                        engine->semaphore.signal = gen8_rcs_signal;
        } else if (INTEL_GEN(dev_priv) >= 6) {
                engine->init_context = intel_rcs_ctx_init;
                engine->flush = gen7_render_ring_flush;
                if (IS_GEN6(dev_priv))
                        engine->flush = gen6_render_ring_flush;
        } else if (IS_GEN5(dev_priv)) {
                engine->flush = gen4_render_ring_flush;
        } else {
                if (INTEL_GEN(dev_priv) < 4)
                        engine->flush = gen2_render_ring_flush;
                else
                        engine->flush = gen4_render_ring_flush;
                engine->irq_enable_mask = I915_USER_INTERRUPT;
        }

        if (IS_HASWELL(dev_priv))
                engine->dispatch_execbuffer = hsw_ring_dispatch_execbuffer;

        engine->init_hw = init_render_ring;
        engine->cleanup = render_ring_cleanup;

        ret = intel_init_ring_buffer(engine);
        if (ret)
                return ret;

        if (INTEL_GEN(dev_priv) >= 6) {
                ret = intel_init_pipe_control(engine, 4096);
                if (ret)
                        return ret;
        } else if (HAS_BROKEN_CS_TLB(dev_priv)) {
                ret = intel_init_pipe_control(engine, I830_WA_SIZE);
                if (ret)
                        return ret;
        }

        return 0;
}

int intel_init_bsd_ring_buffer(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        intel_ring_default_vfuncs(dev_priv, engine);

        if (INTEL_GEN(dev_priv) >= 6) {
                /* gen6 bsd needs a special wa for tail updates */
                if (IS_GEN6(dev_priv))
                        engine->write_tail = gen6_bsd_ring_write_tail;
                engine->flush = gen6_bsd_ring_flush;
                if (INTEL_GEN(dev_priv) < 8)
                        engine->irq_enable_mask = GT_BSD_USER_INTERRUPT;
        } else {
                engine->mmio_base = BSD_RING_BASE;
                engine->flush = bsd_ring_flush;
                if (IS_GEN5(dev_priv))
                        engine->irq_enable_mask = ILK_BSD_USER_INTERRUPT;
                else
                        engine->irq_enable_mask = I915_BSD_USER_INTERRUPT;
        }

        return intel_init_ring_buffer(engine);
}

/**
 * Initialize the second BSD ring (eg. Broadwell GT3, Skylake GT3)
 */
int intel_init_bsd2_ring_buffer(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        intel_ring_default_vfuncs(dev_priv, engine);

        engine->flush = gen6_bsd_ring_flush;

        return intel_init_ring_buffer(engine);
}

int intel_init_blt_ring_buffer(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        intel_ring_default_vfuncs(dev_priv, engine);

        engine->flush = gen6_ring_flush;
        if (INTEL_GEN(dev_priv) < 8)
                engine->irq_enable_mask = GT_BLT_USER_INTERRUPT;

        return intel_init_ring_buffer(engine);
}

int intel_init_vebox_ring_buffer(struct intel_engine_cs *engine)
{
        struct drm_i915_private *dev_priv = engine->i915;

        intel_ring_default_vfuncs(dev_priv, engine);

        engine->flush = gen6_ring_flush;

        if (INTEL_GEN(dev_priv) < 8) {
                engine->irq_enable_mask = PM_VEBOX_USER_INTERRUPT;
                engine->irq_enable = hsw_vebox_irq_enable;
                engine->irq_disable = hsw_vebox_irq_disable;
        }

        return intel_init_ring_buffer(engine);
}

int
intel_engine_flush_all_caches(struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *engine = req->engine;
        int ret;

        if (!engine->gpu_caches_dirty)
                return 0;

        ret = engine->flush(req, 0, I915_GEM_GPU_DOMAINS);
        if (ret)
                return ret;

        trace_i915_gem_ring_flush(req, 0, I915_GEM_GPU_DOMAINS);

        engine->gpu_caches_dirty = false;
        return 0;
}

int
intel_engine_invalidate_all_caches(struct drm_i915_gem_request *req)
{
        struct intel_engine_cs *engine = req->engine;
        uint32_t flush_domains;
        int ret;

        flush_domains = 0;
        if (engine->gpu_caches_dirty)
                flush_domains = I915_GEM_GPU_DOMAINS;

        ret = engine->flush(req, I915_GEM_GPU_DOMAINS, flush_domains);
        if (ret)
                return ret;

        trace_i915_gem_ring_flush(req, I915_GEM_GPU_DOMAINS, flush_domains);

        engine->gpu_caches_dirty = false;
        return 0;
}

void intel_engine_stop(struct intel_engine_cs *engine)
{
        int ret;

        if (!intel_engine_initialized(engine))
                return;

        ret = intel_engine_idle(engine);
        if (ret)
                DRM_ERROR("failed to quiesce %s whilst cleaning up: %d\n",
                          engine->name, ret);

        stop_ring(engine);
}