First Support on Ginger and OMAP TI

[linux-ginger.git] / drivers / gpu / drm / drm_crtc_helper.c

/*
 * Copyright (c) 2006-2008 Intel Corporation
 * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
 *
 * DRM core CRTC related functions
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting documentation, and
 * that the name of the copyright holders not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  The copyright holders make no representations
 * about the suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 *
 * Authors:
 *      Keith Packard
 *      Eric Anholt <eric@anholt.net>
 *      Dave Airlie <airlied@linux.ie>
 *      Jesse Barnes <jesse.barnes@intel.com>
 */

#include "drmP.h"
#include "drm_crtc.h"
#include "drm_crtc_helper.h"
#include "drm_fb_helper.h"

static void drm_mode_validate_flag(struct drm_connector *connector,
                                   int flags)
{
        struct drm_display_mode *mode, *t;

        if (flags == (DRM_MODE_FLAG_DBLSCAN | DRM_MODE_FLAG_INTERLACE))
                return;

        list_for_each_entry_safe(mode, t, &connector->modes, head) {
                if ((mode->flags & DRM_MODE_FLAG_INTERLACE) &&
                                !(flags & DRM_MODE_FLAG_INTERLACE))
                        mode->status = MODE_NO_INTERLACE;
                if ((mode->flags & DRM_MODE_FLAG_DBLSCAN) &&
                                !(flags & DRM_MODE_FLAG_DBLSCAN))
                        mode->status = MODE_NO_DBLESCAN;
        }

        return;
}

/**
 * drm_helper_probe_connector_modes - get complete set of display modes
 * @dev: DRM device
 * @maxX: max width for modes
 * @maxY: max height for modes
 *
 * LOCKING:
 * Caller must hold mode config lock.
 *
 * Based on @dev's mode_config layout, scan all the connectors and try to detect
 * modes on them.  Modes will first be added to the connector's probed_modes
 * list, then culled (based on validity and the @maxX, @maxY parameters) and
 * put into the normal modes list.
 *
 * Intended to be used either at bootup time or when major configuration
 * changes have occurred.
 *
 * FIXME: take into account monitor limits
 *
 * RETURNS:
 * Number of modes found on @connector.
 */
int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
                                            uint32_t maxX, uint32_t maxY)
{
        struct drm_device *dev = connector->dev;
        struct drm_display_mode *mode, *t;
        struct drm_connector_helper_funcs *connector_funcs =
                connector->helper_private;
        int count = 0;
        int mode_flags = 0;

        DRM_DEBUG_KMS("%s\n", drm_get_connector_name(connector));
        /* set all modes to the unverified state */
        list_for_each_entry_safe(mode, t, &connector->modes, head)
                mode->status = MODE_UNVERIFIED;

        if (connector->force) {
                if (connector->force == DRM_FORCE_ON)
                        connector->status = connector_status_connected;
                else
                        connector->status = connector_status_disconnected;
                if (connector->funcs->force)
                        connector->funcs->force(connector);
        } else
                connector->status = connector->funcs->detect(connector);

        if (connector->status == connector_status_disconnected) {
                DRM_DEBUG_KMS("%s is disconnected\n",
                          drm_get_connector_name(connector));
                goto prune;
        }

        count = (*connector_funcs->get_modes)(connector);
        if (!count) {
                count = drm_add_modes_noedid(connector, 800, 600);
                if (!count)
                        return 0;
        }

        drm_mode_connector_list_update(connector);

        if (maxX && maxY)
                drm_mode_validate_size(dev, &connector->modes, maxX,
                                       maxY, 0);

        if (connector->interlace_allowed)
                mode_flags |= DRM_MODE_FLAG_INTERLACE;
        if (connector->doublescan_allowed)
                mode_flags |= DRM_MODE_FLAG_DBLSCAN;
        drm_mode_validate_flag(connector, mode_flags);

        list_for_each_entry_safe(mode, t, &connector->modes, head) {
                if (mode->status == MODE_OK)
                        mode->status = connector_funcs->mode_valid(connector,
                                                                   mode);
        }

prune:
        drm_mode_prune_invalid(dev, &connector->modes, true);

        if (list_empty(&connector->modes))
                return 0;

        drm_mode_sort(&connector->modes);

        DRM_DEBUG_KMS("Probed modes for %s\n",
                                drm_get_connector_name(connector));
        list_for_each_entry_safe(mode, t, &connector->modes, head) {
                mode->vrefresh = drm_mode_vrefresh(mode);

                drm_mode_set_crtcinfo(mode, CRTC_INTERLACE_HALVE_V);
                drm_mode_debug_printmodeline(mode);
        }

        return count;
}
EXPORT_SYMBOL(drm_helper_probe_single_connector_modes);

int drm_helper_probe_connector_modes(struct drm_device *dev, uint32_t maxX,
                                      uint32_t maxY)
{
        struct drm_connector *connector;
        int count = 0;

        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
                count += drm_helper_probe_single_connector_modes(connector,
                                                                 maxX, maxY);
        }

        return count;
}
EXPORT_SYMBOL(drm_helper_probe_connector_modes);

/**
 * drm_helper_encoder_in_use - check if a given encoder is in use
 * @encoder: encoder to check
 *
 * LOCKING:
 * Caller must hold mode config lock.
 *
 * Walk @encoders's DRM device's mode_config and see if it's in use.
 *
 * RETURNS:
 * True if @encoder is part of the mode_config, false otherwise.
 */
bool drm_helper_encoder_in_use(struct drm_encoder *encoder)
{
        struct drm_connector *connector;
        struct drm_device *dev = encoder->dev;
        list_for_each_entry(connector, &dev->mode_config.connector_list, head)
                if (connector->encoder == encoder)
                        return true;
        return false;
}
EXPORT_SYMBOL(drm_helper_encoder_in_use);

/**
 * drm_helper_crtc_in_use - check if a given CRTC is in a mode_config
 * @crtc: CRTC to check
 *
 * LOCKING:
 * Caller must hold mode config lock.
 *
 * Walk @crtc's DRM device's mode_config and see if it's in use.
 *
 * RETURNS:
 * True if @crtc is part of the mode_config, false otherwise.
 */
bool drm_helper_crtc_in_use(struct drm_crtc *crtc)
{
        struct drm_encoder *encoder;
        struct drm_device *dev = crtc->dev;
        /* FIXME: Locking around list access? */
        list_for_each_entry(encoder, &dev->mode_config.encoder_list, head)
                if (encoder->crtc == crtc && drm_helper_encoder_in_use(encoder))
                        return true;
        return false;
}
EXPORT_SYMBOL(drm_helper_crtc_in_use);

/**
 * drm_disable_unused_functions - disable unused objects
 * @dev: DRM device
 *
 * LOCKING:
 * Caller must hold mode config lock.
 *
 * If an connector or CRTC isn't part of @dev's mode_config, it can be disabled
 * by calling its dpms function, which should power it off.
 */
void drm_helper_disable_unused_functions(struct drm_device *dev)
{
        struct drm_encoder *encoder;
        struct drm_connector *connector;
        struct drm_encoder_helper_funcs *encoder_funcs;
        struct drm_crtc *crtc;

        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
                if (!connector->encoder)
                        continue;
                if (connector->status == connector_status_disconnected)
                        connector->encoder = NULL;
        }

        list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
                encoder_funcs = encoder->helper_private;
                if (!drm_helper_encoder_in_use(encoder)) {
                        if (encoder_funcs->disable)
                                (*encoder_funcs->disable)(encoder);
                        else
                                (*encoder_funcs->dpms)(encoder, DRM_MODE_DPMS_OFF);
                        /* disconnector encoder from any connector */
                        encoder->crtc = NULL;
                }
        }

        list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
                struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
                crtc->enabled = drm_helper_crtc_in_use(crtc);
                if (!crtc->enabled) {
                        crtc_funcs->dpms(crtc, DRM_MODE_DPMS_OFF);
                        crtc->fb = NULL;
                }
        }
}
EXPORT_SYMBOL(drm_helper_disable_unused_functions);

static struct drm_display_mode *drm_has_preferred_mode(struct drm_connector *connector, int width, int height)
{
        struct drm_display_mode *mode;

        list_for_each_entry(mode, &connector->modes, head) {
                if (drm_mode_width(mode) > width ||
                    drm_mode_height(mode) > height)
                        continue;
                if (mode->type & DRM_MODE_TYPE_PREFERRED)
                        return mode;
        }
        return NULL;
}

static bool drm_has_cmdline_mode(struct drm_connector *connector)
{
        struct drm_fb_helper_connector *fb_help_conn = connector->fb_helper_private;
        struct drm_fb_helper_cmdline_mode *cmdline_mode;

        if (!fb_help_conn)
                return false;

        cmdline_mode = &fb_help_conn->cmdline_mode;
        return cmdline_mode->specified;
}

static struct drm_display_mode *drm_pick_cmdline_mode(struct drm_connector *connector, int width, int height)
{
        struct drm_fb_helper_connector *fb_help_conn = connector->fb_helper_private;
        struct drm_fb_helper_cmdline_mode *cmdline_mode;
        struct drm_display_mode *mode = NULL;

        if (!fb_help_conn)
                return mode;

        cmdline_mode = &fb_help_conn->cmdline_mode;
        if (cmdline_mode->specified == false)
                return mode;

        /* attempt to find a matching mode in the list of modes
         *  we have gotten so far, if not add a CVT mode that conforms
         */
        if (cmdline_mode->rb || cmdline_mode->margins)
                goto create_mode;

        list_for_each_entry(mode, &connector->modes, head) {
                /* check width/height */
                if (mode->hdisplay != cmdline_mode->xres ||
                    mode->vdisplay != cmdline_mode->yres)
                        continue;

                if (cmdline_mode->refresh_specified) {
                        if (mode->vrefresh != cmdline_mode->refresh)
                                continue;
                }

                if (cmdline_mode->interlace) {
                        if (!(mode->flags & DRM_MODE_FLAG_INTERLACE))
                                continue;
                }
                return mode;
        }

create_mode:
        mode = drm_cvt_mode(connector->dev, cmdline_mode->xres,
                            cmdline_mode->yres,
                            cmdline_mode->refresh_specified ? cmdline_mode->refresh : 60,
                            cmdline_mode->rb, cmdline_mode->interlace,
                            cmdline_mode->margins);
        list_add(&mode->head, &connector->modes);
        return mode;
}

static bool drm_connector_enabled(struct drm_connector *connector, bool strict)
{
        bool enable;

        if (strict) {
                enable = connector->status == connector_status_connected;
        } else {
                enable = connector->status != connector_status_disconnected;
        }
        return enable;
}

static void drm_enable_connectors(struct drm_device *dev, bool *enabled)
{
        bool any_enabled = false;
        struct drm_connector *connector;
        int i = 0;

        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
                enabled[i] = drm_connector_enabled(connector, true);
                DRM_DEBUG_KMS("connector %d enabled? %s\n", connector->base.id,
                          enabled[i] ? "yes" : "no");
                any_enabled |= enabled[i];
                i++;
        }

        if (any_enabled)
                return;

        i = 0;
        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
                enabled[i] = drm_connector_enabled(connector, false);
                i++;
        }
}

static bool drm_target_preferred(struct drm_device *dev,
                                 struct drm_display_mode **modes,
                                 bool *enabled, int width, int height)
{
        struct drm_connector *connector;
        int i = 0;

        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {

                if (enabled[i] == false) {
                        i++;
                        continue;
                }

                DRM_DEBUG_KMS("looking for cmdline mode on connector %d\n",
                              connector->base.id);

                /* got for command line mode first */
                modes[i] = drm_pick_cmdline_mode(connector, width, height);
                if (!modes[i]) {
                        DRM_DEBUG_KMS("looking for preferred mode on connector %d\n",
                                      connector->base.id);
                        modes[i] = drm_has_preferred_mode(connector, width, height);
                }
                /* No preferred modes, pick one off the list */
                if (!modes[i] && !list_empty(&connector->modes)) {
                        list_for_each_entry(modes[i], &connector->modes, head)
                                break;
                }
                DRM_DEBUG_KMS("found mode %s\n", modes[i] ? modes[i]->name :
                          "none");
                i++;
        }
        return true;
}

static int drm_pick_crtcs(struct drm_device *dev,
                          struct drm_crtc **best_crtcs,
                          struct drm_display_mode **modes,
                          int n, int width, int height)
{
        int c, o;
        struct drm_connector *connector;
        struct drm_connector_helper_funcs *connector_funcs;
        struct drm_encoder *encoder;
        struct drm_crtc *best_crtc;
        int my_score, best_score, score;
        struct drm_crtc **crtcs, *crtc;

        if (n == dev->mode_config.num_connector)
                return 0;
        c = 0;
        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
                if (c == n)
                        break;
                c++;
        }

        best_crtcs[n] = NULL;
        best_crtc = NULL;
        best_score = drm_pick_crtcs(dev, best_crtcs, modes, n+1, width, height);
        if (modes[n] == NULL)
                return best_score;

        crtcs = kmalloc(dev->mode_config.num_connector *
                        sizeof(struct drm_crtc *), GFP_KERNEL);
        if (!crtcs)
                return best_score;

        my_score = 1;
        if (connector->status == connector_status_connected)
                my_score++;
        if (drm_has_cmdline_mode(connector))
                my_score++;
        if (drm_has_preferred_mode(connector, width, height))
                my_score++;

        connector_funcs = connector->helper_private;
        encoder = connector_funcs->best_encoder(connector);
        if (!encoder)
                goto out;

        connector->encoder = encoder;

        /* select a crtc for this connector and then attempt to configure
           remaining connectors */
        c = 0;
        list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {

                if ((encoder->possible_crtcs & (1 << c)) == 0) {
                        c++;
                        continue;
                }

                for (o = 0; o < n; o++)
                        if (best_crtcs[o] == crtc)
                                break;

                if (o < n) {
                        /* ignore cloning for now */
                        c++;
                        continue;
                }

                crtcs[n] = crtc;
                memcpy(crtcs, best_crtcs, n * sizeof(struct drm_crtc *));
                score = my_score + drm_pick_crtcs(dev, crtcs, modes, n + 1,
                                                  width, height);
                if (score > best_score) {
                        best_crtc = crtc;
                        best_score = score;
                        memcpy(best_crtcs, crtcs,
                               dev->mode_config.num_connector *
                               sizeof(struct drm_crtc *));
                }
                c++;
        }
out:
        kfree(crtcs);
        return best_score;
}

static void drm_setup_crtcs(struct drm_device *dev)
{
        struct drm_crtc **crtcs;
        struct drm_display_mode **modes;
        struct drm_encoder *encoder;
        struct drm_connector *connector;
        bool *enabled;
        int width, height;
        int i, ret;

        DRM_DEBUG_KMS("\n");

        width = dev->mode_config.max_width;
        height = dev->mode_config.max_height;

        /* clean out all the encoder/crtc combos */
        list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
                encoder->crtc = NULL;
        }

        crtcs = kcalloc(dev->mode_config.num_connector,
                        sizeof(struct drm_crtc *), GFP_KERNEL);
        modes = kcalloc(dev->mode_config.num_connector,
                        sizeof(struct drm_display_mode *), GFP_KERNEL);
        enabled = kcalloc(dev->mode_config.num_connector,
                          sizeof(bool), GFP_KERNEL);

        drm_enable_connectors(dev, enabled);

        ret = drm_target_preferred(dev, modes, enabled, width, height);
        if (!ret)
                DRM_ERROR("Unable to find initial modes\n");

        DRM_DEBUG_KMS("picking CRTCs for %dx%d config\n", width, height);

        drm_pick_crtcs(dev, crtcs, modes, 0, width, height);

        i = 0;
        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
                struct drm_display_mode *mode = modes[i];
                struct drm_crtc *crtc = crtcs[i];

                if (connector->encoder == NULL) {
                        i++;
                        continue;
                }

                if (mode && crtc) {
                        DRM_DEBUG_KMS("desired mode %s set on crtc %d\n",
                                  mode->name, crtc->base.id);
                        crtc->desired_mode = mode;
                        connector->encoder->crtc = crtc;
                } else {
                        connector->encoder->crtc = NULL;
                        connector->encoder = NULL;
                }
                i++;
        }

        kfree(crtcs);
        kfree(modes);
        kfree(enabled);
}

/**
 * drm_encoder_crtc_ok - can a given crtc drive a given encoder?
 * @encoder: encoder to test
 * @crtc: crtc to test
 *
 * Return false if @encoder can't be driven by @crtc, true otherwise.
 */
static bool drm_encoder_crtc_ok(struct drm_encoder *encoder,
                                struct drm_crtc *crtc)
{
        struct drm_device *dev;
        struct drm_crtc *tmp;
        int crtc_mask = 1;

        WARN(!crtc, "checking null crtc?");

        dev = crtc->dev;

        list_for_each_entry(tmp, &dev->mode_config.crtc_list, head) {
                if (tmp == crtc)
                        break;
                crtc_mask <<= 1;
        }

        if (encoder->possible_crtcs & crtc_mask)
                return true;
        return false;
}

/*
 * Check the CRTC we're going to map each output to vs. its current
 * CRTC.  If they don't match, we have to disable the output and the CRTC
 * since the driver will have to re-route things.
 */
static void
drm_crtc_prepare_encoders(struct drm_device *dev)
{
        struct drm_encoder_helper_funcs *encoder_funcs;
        struct drm_encoder *encoder;

        list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
                encoder_funcs = encoder->helper_private;
                /* Disable unused encoders */
                if (encoder->crtc == NULL)
                        (*encoder_funcs->dpms)(encoder, DRM_MODE_DPMS_OFF);
                /* Disable encoders whose CRTC is about to change */
                if (encoder_funcs->get_crtc &&
                    encoder->crtc != (*encoder_funcs->get_crtc)(encoder))
                        (*encoder_funcs->dpms)(encoder, DRM_MODE_DPMS_OFF);
        }
}

/**
 * drm_crtc_set_mode - set a mode
 * @crtc: CRTC to program
 * @mode: mode to use
 * @x: width of mode
 * @y: height of mode
 *
 * LOCKING:
 * Caller must hold mode config lock.
 *
 * Try to set @mode on @crtc.  Give @crtc and its associated connectors a chance
 * to fixup or reject the mode prior to trying to set it.
 *
 * RETURNS:
 * True if the mode was set successfully, or false otherwise.
 */
bool drm_crtc_helper_set_mode(struct drm_crtc *crtc,
                              struct drm_display_mode *mode,
                              int x, int y,
                              struct drm_framebuffer *old_fb)
{
        struct drm_device *dev = crtc->dev;
        struct drm_display_mode *adjusted_mode, saved_mode;
        struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
        struct drm_encoder_helper_funcs *encoder_funcs;
        int saved_x, saved_y;
        struct drm_encoder *encoder;
        bool ret = true;

        adjusted_mode = drm_mode_duplicate(dev, mode);

        crtc->enabled = drm_helper_crtc_in_use(crtc);

        if (!crtc->enabled)
                return true;

        saved_mode = crtc->mode;
        saved_x = crtc->x;
        saved_y = crtc->y;

        /* Update crtc values up front so the driver can rely on them for mode
         * setting.
         */
        crtc->mode = *mode;
        crtc->x = x;
        crtc->y = y;

        /* Pass our mode to the connectors and the CRTC to give them a chance to
         * adjust it according to limitations or connector properties, and also
         * a chance to reject the mode entirely.
         */
        list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {

                if (encoder->crtc != crtc)
                        continue;
                encoder_funcs = encoder->helper_private;
                if (!(ret = encoder_funcs->mode_fixup(encoder, mode,
                                                      adjusted_mode))) {
                        goto done;
                }
        }

        if (!(ret = crtc_funcs->mode_fixup(crtc, mode, adjusted_mode))) {
                goto done;
        }

        /* Prepare the encoders and CRTCs before setting the mode. */
        list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {

                if (encoder->crtc != crtc)
                        continue;
                encoder_funcs = encoder->helper_private;
                /* Disable the encoders as the first thing we do. */
                encoder_funcs->prepare(encoder);
        }

        drm_crtc_prepare_encoders(dev);

        crtc_funcs->prepare(crtc);

        /* Set up the DPLL and any encoders state that needs to adjust or depend
         * on the DPLL.
         */
        ret = !crtc_funcs->mode_set(crtc, mode, adjusted_mode, x, y, old_fb);
        if (!ret)
            goto done;

        list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {

                if (encoder->crtc != crtc)
                        continue;

                DRM_INFO("%s: set mode %s %x\n", drm_get_encoder_name(encoder),
                         mode->name, mode->base.id);
                encoder_funcs = encoder->helper_private;
                encoder_funcs->mode_set(encoder, mode, adjusted_mode);
        }

        /* Now enable the clocks, plane, pipe, and connectors that we set up. */
        crtc_funcs->commit(crtc);

        list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {

                if (encoder->crtc != crtc)
                        continue;

                encoder_funcs = encoder->helper_private;
                encoder_funcs->commit(encoder);

        }

        /* XXX free adjustedmode */
        drm_mode_destroy(dev, adjusted_mode);
        /* FIXME: add subpixel order */
done:
        if (!ret) {
                crtc->mode = saved_mode;
                crtc->x = saved_x;
                crtc->y = saved_y;
        }

        return ret;
}
EXPORT_SYMBOL(drm_crtc_helper_set_mode);


/**
 * drm_crtc_helper_set_config - set a new config from userspace
 * @crtc: CRTC to setup
 * @crtc_info: user provided configuration
 * @new_mode: new mode to set
 * @connector_set: set of connectors for the new config
 * @fb: new framebuffer
 *
 * LOCKING:
 * Caller must hold mode config lock.
 *
 * Setup a new configuration, provided by the user in @crtc_info, and enable
 * it.
 *
 * RETURNS:
 * Zero. (FIXME)
 */
int drm_crtc_helper_set_config(struct drm_mode_set *set)
{
        struct drm_device *dev;
        struct drm_crtc *save_crtcs, *new_crtc, *crtc;
        struct drm_encoder *save_encoders, *new_encoder, *encoder;
        struct drm_framebuffer *old_fb = NULL;
        bool mode_changed = false; /* if true do a full mode set */
        bool fb_changed = false; /* if true and !mode_changed just do a flip */
        struct drm_connector *save_connectors, *connector;
        int count = 0, ro, fail = 0;
        struct drm_crtc_helper_funcs *crtc_funcs;
        int ret = 0;

        DRM_DEBUG_KMS("\n");

        if (!set)
                return -EINVAL;

        if (!set->crtc)
                return -EINVAL;

        if (!set->crtc->helper_private)
                return -EINVAL;

        crtc_funcs = set->crtc->helper_private;

        DRM_DEBUG_KMS("crtc: %p %d fb: %p connectors: %p num_connectors:"
                        " %d (x, y) (%i, %i)\n",
                  set->crtc, set->crtc->base.id, set->fb, set->connectors,
                  (int)set->num_connectors, set->x, set->y);

        dev = set->crtc->dev;

        /* Allocate space for the backup of all (non-pointer) crtc, encoder and
         * connector data. */
        save_crtcs = kzalloc(dev->mode_config.num_crtc *
                             sizeof(struct drm_crtc), GFP_KERNEL);
        if (!save_crtcs)
                return -ENOMEM;

        save_encoders = kzalloc(dev->mode_config.num_encoder *
                                sizeof(struct drm_encoder), GFP_KERNEL);
        if (!save_encoders) {
                kfree(save_crtcs);
                return -ENOMEM;
        }

        save_connectors = kzalloc(dev->mode_config.num_connector *
                                sizeof(struct drm_connector), GFP_KERNEL);
        if (!save_connectors) {
                kfree(save_crtcs);
                kfree(save_encoders);
                return -ENOMEM;
        }

        /* Copy data. Note that driver private data is not affected.
         * Should anything bad happen only the expected state is
         * restored, not the drivers personal bookkeeping.
         */
        count = 0;
        list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
                save_crtcs[count++] = *crtc;
        }

        count = 0;
        list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
                save_encoders[count++] = *encoder;
        }

        count = 0;
        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
                save_connectors[count++] = *connector;
        }

        /* We should be able to check here if the fb has the same properties
         * and then just flip_or_move it */
        if (set->crtc->fb != set->fb) {
                /* If we have no fb then treat it as a full mode set */
                if (set->crtc->fb == NULL) {
                        DRM_DEBUG_KMS("crtc has no fb, full mode set\n");
                        mode_changed = true;
                } else if (set->fb == NULL) {
                        mode_changed = true;
                } else if ((set->fb->bits_per_pixel !=
                         set->crtc->fb->bits_per_pixel) ||
                         set->fb->depth != set->crtc->fb->depth)
                        fb_changed = true;
                else
                        fb_changed = true;
        }

        if (set->x != set->crtc->x || set->y != set->crtc->y)
                fb_changed = true;

        if (set->mode && !drm_mode_equal(set->mode, &set->crtc->mode)) {
                DRM_DEBUG_KMS("modes are different, full mode set\n");
                drm_mode_debug_printmodeline(&set->crtc->mode);
                drm_mode_debug_printmodeline(set->mode);
                mode_changed = true;
        }

        /* a) traverse passed in connector list and get encoders for them */
        count = 0;
        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
                struct drm_connector_helper_funcs *connector_funcs =
                        connector->helper_private;
                new_encoder = connector->encoder;
                for (ro = 0; ro < set->num_connectors; ro++) {
                        if (set->connectors[ro] == connector) {
                                new_encoder = connector_funcs->best_encoder(connector);
                                /* if we can't get an encoder for a connector
                                   we are setting now - then fail */
                                if (new_encoder == NULL)
                                        /* don't break so fail path works correct */
                                        fail = 1;
                                break;
                        }
                }

                if (new_encoder != connector->encoder) {
                        DRM_DEBUG_KMS("encoder changed, full mode switch\n");
                        mode_changed = true;
                        /* If the encoder is reused for another connector, then
                         * the appropriate crtc will be set later.
                         */
                        if (connector->encoder)
                                connector->encoder->crtc = NULL;
                        connector->encoder = new_encoder;
                }
        }

        if (fail) {
                ret = -EINVAL;
                goto fail;
        }

        count = 0;
        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
                if (!connector->encoder)
                        continue;

                if (connector->encoder->crtc == set->crtc)
                        new_crtc = NULL;
                else
                        new_crtc = connector->encoder->crtc;

                for (ro = 0; ro < set->num_connectors; ro++) {
                        if (set->connectors[ro] == connector)
                                new_crtc = set->crtc;
                }

                /* Make sure the new CRTC will work with the encoder */
                if (new_crtc &&
                    !drm_encoder_crtc_ok(connector->encoder, new_crtc)) {
                        ret = -EINVAL;
                        goto fail;
                }
                if (new_crtc != connector->encoder->crtc) {
                        DRM_DEBUG_KMS("crtc changed, full mode switch\n");
                        mode_changed = true;
                        connector->encoder->crtc = new_crtc;
                }
                DRM_DEBUG_KMS("setting connector %d crtc to %p\n",
                          connector->base.id, new_crtc);
        }

        /* mode_set_base is not a required function */
        if (fb_changed && !crtc_funcs->mode_set_base)
                mode_changed = true;

        if (mode_changed) {
                old_fb = set->crtc->fb;
                set->crtc->fb = set->fb;
                set->crtc->enabled = (set->mode != NULL);
                if (set->mode != NULL) {
                        DRM_DEBUG_KMS("attempting to set mode from"
                                        " userspace\n");
                        drm_mode_debug_printmodeline(set->mode);
                        if (!drm_crtc_helper_set_mode(set->crtc, set->mode,
                                                      set->x, set->y,
                                                      old_fb)) {
                                DRM_ERROR("failed to set mode on crtc %p\n",
                                          set->crtc);
                                ret = -EINVAL;
                                goto fail;
                        }
                        /* TODO are these needed? */
                        set->crtc->desired_x = set->x;
                        set->crtc->desired_y = set->y;
                        set->crtc->desired_mode = set->mode;
                }
                drm_helper_disable_unused_functions(dev);
        } else if (fb_changed) {
                set->crtc->x = set->x;
                set->crtc->y = set->y;

                old_fb = set->crtc->fb;
                if (set->crtc->fb != set->fb)
                        set->crtc->fb = set->fb;
                ret = crtc_funcs->mode_set_base(set->crtc,
                                                set->x, set->y, old_fb);
                if (ret != 0)
                        goto fail;
        }

        kfree(save_connectors);
        kfree(save_encoders);
        kfree(save_crtcs);
        return 0;

fail:
        /* Restore all previous data. */
        count = 0;
        list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {
                *crtc = save_crtcs[count++];
        }

        count = 0;
        list_for_each_entry(encoder, &dev->mode_config.encoder_list, head) {
                *encoder = save_encoders[count++];
        }

        count = 0;
        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
                *connector = save_connectors[count++];
        }

        kfree(save_connectors);
        kfree(save_encoders);
        kfree(save_crtcs);
        return ret;
}
EXPORT_SYMBOL(drm_crtc_helper_set_config);

bool drm_helper_plugged_event(struct drm_device *dev)
{
        DRM_DEBUG_KMS("\n");

        drm_helper_probe_connector_modes(dev, dev->mode_config.max_width,
                                         dev->mode_config.max_height);

        drm_setup_crtcs(dev);

        /* alert the driver fb layer */
        dev->mode_config.funcs->fb_changed(dev);

        /* FIXME: send hotplug event */
        return true;
}
/**
 * drm_initial_config - setup a sane initial connector configuration
 * @dev: DRM device
 *
 * LOCKING:
 * Called at init time, must take mode config lock.
 *
 * Scan the CRTCs and connectors and try to put together an initial setup.
 * At the moment, this is a cloned configuration across all heads with
 * a new framebuffer object as the backing store.
 *
 * RETURNS:
 * Zero if everything went ok, nonzero otherwise.
 */
bool drm_helper_initial_config(struct drm_device *dev)
{
        int count = 0;

        drm_fb_helper_parse_command_line(dev);

        count = drm_helper_probe_connector_modes(dev,
                                                 dev->mode_config.max_width,
                                                 dev->mode_config.max_height);

        /*
         * we shouldn't end up with no modes here.
         */
        WARN(!count, "No connectors reported connected with modes\n");

        drm_setup_crtcs(dev);

        /* alert the driver fb layer */
        dev->mode_config.funcs->fb_changed(dev);

        return 0;
}
EXPORT_SYMBOL(drm_helper_initial_config);

static int drm_helper_choose_encoder_dpms(struct drm_encoder *encoder)
{
        int dpms = DRM_MODE_DPMS_OFF;
        struct drm_connector *connector;
        struct drm_device *dev = encoder->dev;

        list_for_each_entry(connector, &dev->mode_config.connector_list, head)
                if (connector->encoder == encoder)
                        if (connector->dpms < dpms)
                                dpms = connector->dpms;
        return dpms;
}

static int drm_helper_choose_crtc_dpms(struct drm_crtc *crtc)
{
        int dpms = DRM_MODE_DPMS_OFF;
        struct drm_connector *connector;
        struct drm_device *dev = crtc->dev;

        list_for_each_entry(connector, &dev->mode_config.connector_list, head)
                if (connector->encoder && connector->encoder->crtc == crtc)
                        if (connector->dpms < dpms)
                                dpms = connector->dpms;
        return dpms;
}

/**
 * drm_helper_connector_dpms
 * @connector affected connector
 * @mode DPMS mode
 *
 * Calls the low-level connector DPMS function, then
 * calls appropriate encoder and crtc DPMS functions as well
 */
void drm_helper_connector_dpms(struct drm_connector *connector, int mode)
{
        struct drm_encoder *encoder = connector->encoder;
        struct drm_crtc *crtc = encoder ? encoder->crtc : NULL;
        int old_dpms;

        if (mode == connector->dpms)
                return;

        old_dpms = connector->dpms;
        connector->dpms = mode;

        /* from off to on, do crtc then encoder */
        if (mode < old_dpms) {
                if (crtc) {
                        struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
                        if (crtc_funcs->dpms)
                                (*crtc_funcs->dpms) (crtc,
                                                     drm_helper_choose_crtc_dpms(crtc));
                }
                if (encoder) {
                        struct drm_encoder_helper_funcs *encoder_funcs = encoder->helper_private;
                        if (encoder_funcs->dpms)
                                (*encoder_funcs->dpms) (encoder,
                                                        drm_helper_choose_encoder_dpms(encoder));
                }
        }

        /* from on to off, do encoder then crtc */
        if (mode > old_dpms) {
                if (encoder) {
                        struct drm_encoder_helper_funcs *encoder_funcs = encoder->helper_private;
                        if (encoder_funcs->dpms)
                                (*encoder_funcs->dpms) (encoder,
                                                        drm_helper_choose_encoder_dpms(encoder));
                }
                if (crtc) {
                        struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
                        if (crtc_funcs->dpms)
                                (*crtc_funcs->dpms) (crtc,
                                                     drm_helper_choose_crtc_dpms(crtc));
                }
        }

        return;
}
EXPORT_SYMBOL(drm_helper_connector_dpms);

/**
 * drm_hotplug_stage_two
 * @dev DRM device
 * @connector hotpluged connector
 *
 * LOCKING.
 * Caller must hold mode config lock, function might grab struct lock.
 *
 * Stage two of a hotplug.
 *
 * RETURNS:
 * Zero on success, errno on failure.
 */
int drm_helper_hotplug_stage_two(struct drm_device *dev)
{
        drm_helper_plugged_event(dev);

        return 0;
}
EXPORT_SYMBOL(drm_helper_hotplug_stage_two);

int drm_helper_mode_fill_fb_struct(struct drm_framebuffer *fb,
                                   struct drm_mode_fb_cmd *mode_cmd)
{
        fb->width = mode_cmd->width;
        fb->height = mode_cmd->height;
        fb->pitch = mode_cmd->pitch;
        fb->bits_per_pixel = mode_cmd->bpp;
        fb->depth = mode_cmd->depth;

        return 0;
}
EXPORT_SYMBOL(drm_helper_mode_fill_fb_struct);

int drm_helper_resume_force_mode(struct drm_device *dev)
{
        struct drm_crtc *crtc;
        int ret;

        list_for_each_entry(crtc, &dev->mode_config.crtc_list, head) {

                if (!crtc->enabled)
                        continue;

                ret = drm_crtc_helper_set_mode(crtc, &crtc->mode,
                                               crtc->x, crtc->y, crtc->fb);

                if (ret == false)
                        DRM_ERROR("failed to set mode on crtc %p\n", crtc);
        }
        /* disable the unused connectors while restoring the modesetting */
        drm_helper_disable_unused_functions(dev);
        return 0;
}
EXPORT_SYMBOL(drm_helper_resume_force_mode);