drivers/gpu/drm/drm_probe_helper.c

   1 /*
   2  * Copyright (c) 2006-2008 Intel Corporation
   3  * Copyright (c) 2007 Dave Airlie <airlied@linux.ie>
   4  *
   5  * DRM core CRTC related functions
   6  *
   7  * Permission to use, copy, modify, distribute, and sell this software and its
   8  * documentation for any purpose is hereby granted without fee, provided that
   9  * the above copyright notice appear in all copies and that both that copyright
  10  * notice and this permission notice appear in supporting documentation, and
  11  * that the name of the copyright holders not be used in advertising or
  12  * publicity pertaining to distribution of the software without specific,
  13  * written prior permission.  The copyright holders make no representations
  14  * about the suitability of this software for any purpose.  It is provided "as
  15  * is" without express or implied warranty.
  16  *
  17  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  18  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  19  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  20  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  21  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  22  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  23  * OF THIS SOFTWARE.
  24  *
  25  * Authors:
  26  *      Keith Packard
  27  *      Eric Anholt <eric@anholt.net>
  28  *      Dave Airlie <airlied@linux.ie>
  29  *      Jesse Barnes <jesse.barnes@intel.com>
  30  */
  31
  32 #include <linux/export.h>
  33 #include <linux/moduleparam.h>
  34
  35 #include <drm/drmP.h>
  36 #include <drm/drm_crtc.h>
  37 #include <drm/drm_fourcc.h>
  38 #include <drm/drm_crtc_helper.h>
  39 #include <drm/drm_fb_helper.h>
  40 #include <drm/drm_edid.h>
  41 #include <drm/drm_modeset_helper_vtables.h>
  42
  43 #include "drm_crtc_helper_internal.h"
  44
  45 /**
  46  * DOC: output probing helper overview
  47  *
  48  * This library provides some helper code for output probing. It provides an
  49  * implementation of the core &drm_connector_funcs.fill_modes interface with
  50  * drm_helper_probe_single_connector_modes().
  51  *
  52  * It also provides support for polling connectors with a work item and for
  53  * generic hotplug interrupt handling where the driver doesn't or cannot keep
  54  * track of a per-connector hpd interrupt.
  55  *
  56  * This helper library can be used independently of the modeset helper library.
  57  * Drivers can also overwrite different parts e.g. use their own hotplug
  58  * handling code to avoid probing unrelated outputs.
  59  *
  60  * The probe helpers share the function table structures with other display
  61  * helper libraries. See &struct drm_connector_helper_funcs for the details.
  62  */
  63
  64 static bool drm_kms_helper_poll = true;
  65 module_param_named(poll, drm_kms_helper_poll, bool, 0600);
  66
  67 static enum drm_mode_status
  68 drm_mode_validate_flag(const struct drm_display_mode *mode,
  69                        int flags)
  70 {
  71         if ((mode->flags & DRM_MODE_FLAG_INTERLACE) &&
  72             !(flags & DRM_MODE_FLAG_INTERLACE))
  73                 return MODE_NO_INTERLACE;
  74
  75         if ((mode->flags & DRM_MODE_FLAG_DBLSCAN) &&
  76             !(flags & DRM_MODE_FLAG_DBLSCAN))
  77                 return MODE_NO_DBLESCAN;
  78
  79         if ((mode->flags & DRM_MODE_FLAG_3D_MASK) &&
  80             !(flags & DRM_MODE_FLAG_3D_MASK))
  81                 return MODE_NO_STEREO;
  82
  83         return MODE_OK;
  84 }
  85
  86 static enum drm_mode_status
  87 drm_mode_validate_pipeline(struct drm_display_mode *mode,
  88                             struct drm_connector *connector)
  89 {
  90         struct drm_device *dev = connector->dev;
  91         uint32_t *ids = connector->encoder_ids;
  92         enum drm_mode_status ret = MODE_OK;
  93         unsigned int i;
  94
  95         /* Step 1: Validate against connector */
  96         ret = drm_connector_mode_valid(connector, mode);
  97         if (ret != MODE_OK)
  98                 return ret;
  99
 100         /* Step 2: Validate against encoders and crtcs */
 101         for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) {
 102                 struct drm_encoder *encoder = drm_encoder_find(dev, NULL, ids[i]);
 103                 struct drm_crtc *crtc;
 104
 105                 if (!encoder)
 106                         continue;
 107
 108                 ret = drm_encoder_mode_valid(encoder, mode);
 109                 if (ret != MODE_OK) {
 110                         /* No point in continuing for crtc check as this encoder
 111                          * will not accept the mode anyway. If all encoders
 112                          * reject the mode then, at exit, ret will not be
 113                          * MODE_OK. */
 114                         continue;
 115                 }
 116
 117                 ret = drm_bridge_mode_valid(encoder->bridge, mode);
 118                 if (ret != MODE_OK) {
 119                         /* There is also no point in continuing for crtc check
 120                          * here. */
 121                         continue;
 122                 }
 123
 124                 drm_for_each_crtc(crtc, dev) {
 125                         if (!drm_encoder_crtc_ok(encoder, crtc))
 126                                 continue;
 127
 128                         ret = drm_crtc_mode_valid(crtc, mode);
 129                         if (ret == MODE_OK) {
 130                                 /* If we get to this point there is at least
 131                                  * one combination of encoder+crtc that works
 132                                  * for this mode. Lets return now. */
 133                                 return ret;
 134                         }
 135                 }
 136         }
 137
 138         return ret;
 139 }
 140
 141 static int drm_helper_probe_add_cmdline_mode(struct drm_connector *connector)
 142 {
 143         struct drm_cmdline_mode *cmdline_mode;
 144         struct drm_display_mode *mode;
 145
 146         cmdline_mode = &connector->cmdline_mode;
 147         if (!cmdline_mode->specified)
 148                 return 0;
 149
 150         /* Only add a GTF mode if we find no matching probed modes */
 151         list_for_each_entry(mode, &connector->probed_modes, head) {
 152                 if (mode->hdisplay != cmdline_mode->xres ||
 153                     mode->vdisplay != cmdline_mode->yres)
 154                         continue;
 155
 156                 if (cmdline_mode->refresh_specified) {
 157                         /* The probed mode's vrefresh is set until later */
 158                         if (drm_mode_vrefresh(mode) != cmdline_mode->refresh)
 159                                 continue;
 160                 }
 161
 162                 return 0;
 163         }
 164
 165         mode = drm_mode_create_from_cmdline_mode(connector->dev,
 166                                                  cmdline_mode);
 167         if (mode == NULL)
 168                 return 0;
 169
 170         drm_mode_probed_add(connector, mode);
 171         return 1;
 172 }
 173
 174 enum drm_mode_status drm_crtc_mode_valid(struct drm_crtc *crtc,
 175                                          const struct drm_display_mode *mode)
 176 {
 177         const struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
 178
 179         if (!crtc_funcs || !crtc_funcs->mode_valid)
 180                 return MODE_OK;
 181
 182         return crtc_funcs->mode_valid(crtc, mode);
 183 }
 184
 185 enum drm_mode_status drm_encoder_mode_valid(struct drm_encoder *encoder,
 186                                             const struct drm_display_mode *mode)
 187 {
 188         const struct drm_encoder_helper_funcs *encoder_funcs =
 189                 encoder->helper_private;
 190
 191         if (!encoder_funcs || !encoder_funcs->mode_valid)
 192                 return MODE_OK;
 193
 194         return encoder_funcs->mode_valid(encoder, mode);
 195 }
 196
 197 enum drm_mode_status drm_connector_mode_valid(struct drm_connector *connector,
 198                                               struct drm_display_mode *mode)
 199 {
 200         const struct drm_connector_helper_funcs *connector_funcs =
 201                 connector->helper_private;
 202
 203         if (!connector_funcs || !connector_funcs->mode_valid)
 204                 return MODE_OK;
 205
 206         return connector_funcs->mode_valid(connector, mode);
 207 }
 208
 209 #define DRM_OUTPUT_POLL_PERIOD (10*HZ)
 210 /**
 211  * drm_kms_helper_poll_enable - re-enable output polling.
 212  * @dev: drm_device
 213  *
 214  * This function re-enables the output polling work, after it has been
 215  * temporarily disabled using drm_kms_helper_poll_disable(), for example over
 216  * suspend/resume.
 217  *
 218  * Drivers can call this helper from their device resume implementation. It is
 219  * not an error to call this even when output polling isn't enabled.
 220  *
 221  * Note that calls to enable and disable polling must be strictly ordered, which
 222  * is automatically the case when they're only call from suspend/resume
 223  * callbacks.
 224  */
 225 void drm_kms_helper_poll_enable(struct drm_device *dev)
 226 {
 227         bool poll = false;
 228         struct drm_connector *connector;
 229         struct drm_connector_list_iter conn_iter;
 230         unsigned long delay = DRM_OUTPUT_POLL_PERIOD;
 231
 232         if (!dev->mode_config.poll_enabled || !drm_kms_helper_poll)
 233                 return;
 234
 235         drm_connector_list_iter_begin(dev, &conn_iter);
 236         drm_for_each_connector_iter(connector, &conn_iter) {
 237                 if (connector->polled & (DRM_CONNECTOR_POLL_CONNECT |
 238                                          DRM_CONNECTOR_POLL_DISCONNECT))
 239                         poll = true;
 240         }
 241         drm_connector_list_iter_end(&conn_iter);
 242
 243         if (dev->mode_config.delayed_event) {
 244                 /*
 245                  * FIXME:
 246                  *
 247                  * Use short (1s) delay to handle the initial delayed event.
 248                  * This delay should not be needed, but Optimus/nouveau will
 249                  * fail in a mysterious way if the delayed event is handled as
 250                  * soon as possible like it is done in
 251                  * drm_helper_probe_single_connector_modes() in case the poll
 252                  * was enabled before.
 253                  */
 254                 poll = true;
 255                 delay = HZ;
 256         }
 257
 258         if (poll)
 259                 schedule_delayed_work(&dev->mode_config.output_poll_work, delay);
 260 }
 261 EXPORT_SYMBOL(drm_kms_helper_poll_enable);
 262
 263 static enum drm_connector_status
 264 drm_helper_probe_detect_ctx(struct drm_connector *connector, bool force)
 265 {
 266         const struct drm_connector_helper_funcs *funcs = connector->helper_private;
 267         struct drm_modeset_acquire_ctx ctx;
 268         int ret;
 269
 270         drm_modeset_acquire_init(&ctx, 0);
 271
 272 retry:
 273         ret = drm_modeset_lock(&connector->dev->mode_config.connection_mutex, &ctx);
 274         if (!ret) {
 275                 if (funcs->detect_ctx)
 276                         ret = funcs->detect_ctx(connector, &ctx, force);
 277                 else if (connector->funcs->detect)
 278                         ret = connector->funcs->detect(connector, force);
 279                 else
 280                         ret = connector_status_connected;
 281         }
 282
 283         if (ret == -EDEADLK) {
 284                 drm_modeset_backoff(&ctx);
 285                 goto retry;
 286         }
 287
 288         if (WARN_ON(ret < 0))
 289                 ret = connector_status_unknown;
 290
 291         drm_modeset_drop_locks(&ctx);
 292         drm_modeset_acquire_fini(&ctx);
 293
 294         return ret;
 295 }
 296
 297 /**
 298  * drm_helper_probe_detect - probe connector status
 299  * @connector: connector to probe
 300  * @ctx: acquire_ctx, or NULL to let this function handle locking.
 301  * @force: Whether destructive probe operations should be performed.
 302  *
 303  * This function calls the detect callbacks of the connector.
 304  * This function returns &drm_connector_status, or
 305  * if @ctx is set, it might also return -EDEADLK.
 306  */
 307 int
 308 drm_helper_probe_detect(struct drm_connector *connector,
 309                         struct drm_modeset_acquire_ctx *ctx,
 310                         bool force)
 311 {
 312         const struct drm_connector_helper_funcs *funcs = connector->helper_private;
 313         struct drm_device *dev = connector->dev;
 314         int ret;
 315
 316         if (!ctx)
 317                 return drm_helper_probe_detect_ctx(connector, force);
 318
 319         ret = drm_modeset_lock(&dev->mode_config.connection_mutex, ctx);
 320         if (ret)
 321                 return ret;
 322
 323         if (funcs->detect_ctx)
 324                 return funcs->detect_ctx(connector, ctx, force);
 325         else if (connector->funcs->detect)
 326                 return connector->funcs->detect(connector, force);
 327         else
 328                 return connector_status_connected;
 329 }
 330 EXPORT_SYMBOL(drm_helper_probe_detect);
 331
 332 /**
 333  * drm_helper_probe_single_connector_modes - get complete set of display modes
 334  * @connector: connector to probe
 335  * @maxX: max width for modes
 336  * @maxY: max height for modes
 337  *
 338  * Based on the helper callbacks implemented by @connector in struct
 339  * &drm_connector_helper_funcs try to detect all valid modes.  Modes will first
 340  * be added to the connector's probed_modes list, then culled (based on validity
 341  * and the @maxX, @maxY parameters) and put into the normal modes list.
 342  *
 343  * Intended to be used as a generic implementation of the
 344  * &drm_connector_funcs.fill_modes() vfunc for drivers that use the CRTC helpers
 345  * for output mode filtering and detection.
 346  *
 347  * The basic procedure is as follows
 348  *
 349  * 1. All modes currently on the connector's modes list are marked as stale
 350  *
 351  * 2. New modes are added to the connector's probed_modes list with
 352  *    drm_mode_probed_add(). New modes start their life with status as OK.
 353  *    Modes are added from a single source using the following priority order.
 354  *
 355  *    - &drm_connector_helper_funcs.get_modes vfunc
 356  *    - if the connector status is connector_status_connected, standard
 357  *      VESA DMT modes up to 1024x768 are automatically added
 358  *      (drm_add_modes_noedid())
 359  *
 360  *    Finally modes specified via the kernel command line (video=...) are
 361  *    added in addition to what the earlier probes produced
 362  *    (drm_helper_probe_add_cmdline_mode()). These modes are generated
 363  *    using the VESA GTF/CVT formulas.
 364  *
 365  * 3. Modes are moved from the probed_modes list to the modes list. Potential
 366  *    duplicates are merged together (see drm_mode_connector_list_update()).
 367  *    After this step the probed_modes list will be empty again.
 368  *
 369  * 4. Any non-stale mode on the modes list then undergoes validation
 370  *
 371  *    - drm_mode_validate_basic() performs basic sanity checks
 372  *    - drm_mode_validate_size() filters out modes larger than @maxX and @maxY
 373  *      (if specified)
 374  *    - drm_mode_validate_flag() checks the modes against basic connector
 375  *      capabilities (interlace_allowed,doublescan_allowed,stereo_allowed)
 376  *    - the optional &drm_connector_helper_funcs.mode_valid helper can perform
 377  *      driver and/or sink specific checks
 378  *    - the optional &drm_crtc_helper_funcs.mode_valid,
 379  *      &drm_bridge_funcs.mode_valid and &drm_encoder_helper_funcs.mode_valid
 380  *      helpers can perform driver and/or source specific checks which are also
 381  *      enforced by the modeset/atomic helpers
 382  *
 383  * 5. Any mode whose status is not OK is pruned from the connector's modes list,
 384  *    accompanied by a debug message indicating the reason for the mode's
 385  *    rejection (see drm_mode_prune_invalid()).
 386  *
 387  * Returns:
 388  * The number of modes found on @connector.
 389  */
 390 int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 391                                             uint32_t maxX, uint32_t maxY)
 392 {
 393         struct drm_device *dev = connector->dev;
 394         struct drm_display_mode *mode;
 395         const struct drm_connector_helper_funcs *connector_funcs =
 396                 connector->helper_private;
 397         int count = 0, ret;
 398         int mode_flags = 0;
 399         bool verbose_prune = true;
 400         enum drm_connector_status old_status;
 401         struct drm_modeset_acquire_ctx ctx;
 402
 403         WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
 404
 405         drm_modeset_acquire_init(&ctx, 0);
 406
 407         DRM_DEBUG_KMS("[CONNECTOR:%d:%s]\n", connector->base.id,
 408                         connector->name);
 409
 410 retry:
 411         ret = drm_modeset_lock(&dev->mode_config.connection_mutex, &ctx);
 412         if (ret == -EDEADLK) {
 413                 drm_modeset_backoff(&ctx);
 414                 goto retry;
 415         } else
 416                 WARN_ON(ret < 0);
 417
 418         /* set all old modes to the stale state */
 419         list_for_each_entry(mode, &connector->modes, head)
 420                 mode->status = MODE_STALE;
 421
 422         old_status = connector->status;
 423
 424         if (connector->force) {
 425                 if (connector->force == DRM_FORCE_ON ||
 426                     connector->force == DRM_FORCE_ON_DIGITAL)
 427                         connector->status = connector_status_connected;
 428                 else
 429                         connector->status = connector_status_disconnected;
 430                 if (connector->funcs->force)
 431                         connector->funcs->force(connector);
 432         } else {
 433                 ret = drm_helper_probe_detect(connector, &ctx, true);
 434
 435                 if (ret == -EDEADLK) {
 436                         drm_modeset_backoff(&ctx);
 437                         goto retry;
 438                 } else if (WARN(ret < 0, "Invalid return value %i for connector detection\n", ret))
 439                         ret = connector_status_unknown;
 440
 441                 connector->status = ret;
 442         }
 443
 444         /*
 445          * Normally either the driver's hpd code or the poll loop should
 446          * pick up any changes and fire the hotplug event. But if
 447          * userspace sneaks in a probe, we might miss a change. Hence
 448          * check here, and if anything changed start the hotplug code.
 449          */
 450         if (old_status != connector->status) {
 451                 DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s to %s\n",
 452                               connector->base.id,
 453                               connector->name,
 454                               drm_get_connector_status_name(old_status),
 455                               drm_get_connector_status_name(connector->status));
 456
 457                 /*
 458                  * The hotplug event code might call into the fb
 459                  * helpers, and so expects that we do not hold any
 460                  * locks. Fire up the poll struct instead, it will
 461                  * disable itself again.
 462                  */
 463                 dev->mode_config.delayed_event = true;
 464                 if (dev->mode_config.poll_enabled)
 465                         schedule_delayed_work(&dev->mode_config.output_poll_work,
 466                                               0);
 467         }
 468
 469         /* Re-enable polling in case the global poll config changed. */
 470         if (drm_kms_helper_poll != dev->mode_config.poll_running)
 471                 drm_kms_helper_poll_enable(dev);
 472
 473         dev->mode_config.poll_running = drm_kms_helper_poll;
 474
 475         if (connector->status == connector_status_disconnected) {
 476                 DRM_DEBUG_KMS("[CONNECTOR:%d:%s] disconnected\n",
 477                         connector->base.id, connector->name);
 478                 drm_mode_connector_update_edid_property(connector, NULL);
 479                 verbose_prune = false;
 480                 goto prune;
 481         }
 482
 483         count = (*connector_funcs->get_modes)(connector);
 484
 485         if (count == 0 && connector->status == connector_status_connected)
 486                 count = drm_add_modes_noedid(connector, 1024, 768);
 487         count += drm_helper_probe_add_cmdline_mode(connector);
 488         if (count == 0)
 489                 goto prune;
 490
 491         drm_mode_connector_list_update(connector);
 492
 493         if (connector->interlace_allowed)
 494                 mode_flags |= DRM_MODE_FLAG_INTERLACE;
 495         if (connector->doublescan_allowed)
 496                 mode_flags |= DRM_MODE_FLAG_DBLSCAN;
 497         if (connector->stereo_allowed)
 498                 mode_flags |= DRM_MODE_FLAG_3D_MASK;
 499
 500         list_for_each_entry(mode, &connector->modes, head) {
 501                 if (mode->status == MODE_OK)
 502                         mode->status = drm_mode_validate_basic(mode);
 503
 504                 if (mode->status == MODE_OK)
 505                         mode->status = drm_mode_validate_size(mode, maxX, maxY);
 506
 507                 if (mode->status == MODE_OK)
 508                         mode->status = drm_mode_validate_flag(mode, mode_flags);
 509
 510                 if (mode->status == MODE_OK)
 511                         mode->status = drm_mode_validate_pipeline(mode,
 512                                                                   connector);
 513
 514                 if (mode->status == MODE_OK)
 515                         mode->status = drm_mode_validate_ycbcr420(mode,
 516                                                                   connector);
 517         }
 518
 519 prune:
 520         drm_mode_prune_invalid(dev, &connector->modes, verbose_prune);
 521
 522         drm_modeset_drop_locks(&ctx);
 523         drm_modeset_acquire_fini(&ctx);
 524
 525         if (list_empty(&connector->modes))
 526                 return 0;
 527
 528         list_for_each_entry(mode, &connector->modes, head)
 529                 mode->vrefresh = drm_mode_vrefresh(mode);
 530
 531         drm_mode_sort(&connector->modes);
 532
 533         DRM_DEBUG_KMS("[CONNECTOR:%d:%s] probed modes :\n", connector->base.id,
 534                         connector->name);
 535         list_for_each_entry(mode, &connector->modes, head) {
 536                 drm_mode_set_crtcinfo(mode, CRTC_INTERLACE_HALVE_V);
 537                 drm_mode_debug_printmodeline(mode);
 538         }
 539
 540         return count;
 541 }
 542 EXPORT_SYMBOL(drm_helper_probe_single_connector_modes);
 543
 544 /**
 545  * drm_kms_helper_hotplug_event - fire off KMS hotplug events
 546  * @dev: drm_device whose connector state changed
 547  *
 548  * This function fires off the uevent for userspace and also calls the
 549  * output_poll_changed function, which is most commonly used to inform the fbdev
 550  * emulation code and allow it to update the fbcon output configuration.
 551  *
 552  * Drivers should call this from their hotplug handling code when a change is
 553  * detected. Note that this function does not do any output detection of its
 554  * own, like drm_helper_hpd_irq_event() does - this is assumed to be done by the
 555  * driver already.
 556  *
 557  * This function must be called from process context with no mode
 558  * setting locks held.
 559  */
 560 void drm_kms_helper_hotplug_event(struct drm_device *dev)
 561 {
 562         /* send a uevent + call fbdev */
 563         drm_sysfs_hotplug_event(dev);
 564         if (dev->mode_config.funcs->output_poll_changed)
 565                 dev->mode_config.funcs->output_poll_changed(dev);
 566 }
 567 EXPORT_SYMBOL(drm_kms_helper_hotplug_event);
 568
 569 static void output_poll_execute(struct work_struct *work)
 570 {
 571         struct delayed_work *delayed_work = to_delayed_work(work);
 572         struct drm_device *dev = container_of(delayed_work, struct drm_device, mode_config.output_poll_work);
 573         struct drm_connector *connector;
 574         struct drm_connector_list_iter conn_iter;
 575         enum drm_connector_status old_status;
 576         bool repoll = false, changed;
 577
 578         /* Pick up any changes detected by the probe functions. */
 579         changed = dev->mode_config.delayed_event;
 580         dev->mode_config.delayed_event = false;
 581
 582         if (!drm_kms_helper_poll)
 583                 goto out;
 584
 585         if (!mutex_trylock(&dev->mode_config.mutex)) {
 586                 repoll = true;
 587                 goto out;
 588         }
 589
 590         drm_connector_list_iter_begin(dev, &conn_iter);
 591         drm_for_each_connector_iter(connector, &conn_iter) {
 592                 /* Ignore forced connectors. */
 593                 if (connector->force)
 594                         continue;
 595
 596                 /* Ignore HPD capable connectors and connectors where we don't
 597                  * want any hotplug detection at all for polling. */
 598                 if (!connector->polled || connector->polled == DRM_CONNECTOR_POLL_HPD)
 599                         continue;
 600
 601                 old_status = connector->status;
 602                 /* if we are connected and don't want to poll for disconnect
 603                    skip it */
 604                 if (old_status == connector_status_connected &&
 605                     !(connector->polled & DRM_CONNECTOR_POLL_DISCONNECT))
 606                         continue;
 607
 608                 repoll = true;
 609
 610                 connector->status = drm_helper_probe_detect(connector, NULL, false);
 611                 if (old_status != connector->status) {
 612                         const char *old, *new;
 613
 614                         /*
 615                          * The poll work sets force=false when calling detect so
 616                          * that drivers can avoid to do disruptive tests (e.g.
 617                          * when load detect cycles could cause flickering on
 618                          * other, running displays). This bears the risk that we
 619                          * flip-flop between unknown here in the poll work and
 620                          * the real state when userspace forces a full detect
 621                          * call after receiving a hotplug event due to this
 622                          * change.
 623                          *
 624                          * Hence clamp an unknown detect status to the old
 625                          * value.
 626                          */
 627                         if (connector->status == connector_status_unknown) {
 628                                 connector->status = old_status;
 629                                 continue;
 630                         }
 631
 632                         old = drm_get_connector_status_name(old_status);
 633                         new = drm_get_connector_status_name(connector->status);
 634
 635                         DRM_DEBUG_KMS("[CONNECTOR:%d:%s] "
 636                                       "status updated from %s to %s\n",
 637                                       connector->base.id,
 638                                       connector->name,
 639                                       old, new);
 640
 641                         changed = true;
 642                 }
 643         }
 644         drm_connector_list_iter_end(&conn_iter);
 645
 646         mutex_unlock(&dev->mode_config.mutex);
 647
 648 out:
 649         if (changed)
 650                 drm_kms_helper_hotplug_event(dev);
 651
 652         if (repoll)
 653                 schedule_delayed_work(delayed_work, DRM_OUTPUT_POLL_PERIOD);
 654 }
 655
 656 /**
 657  * drm_kms_helper_is_poll_worker - is %current task an output poll worker?
 658  *
 659  * Determine if %current task is an output poll worker.  This can be used
 660  * to select distinct code paths for output polling versus other contexts.
 661  *
 662  * One use case is to avoid a deadlock between the output poll worker and
 663  * the autosuspend worker wherein the latter waits for polling to finish
 664  * upon calling drm_kms_helper_poll_disable(), while the former waits for
 665  * runtime suspend to finish upon calling pm_runtime_get_sync() in a
 666  * connector ->detect hook.
 667  */
 668 bool drm_kms_helper_is_poll_worker(void)
 669 {
 670         struct work_struct *work = current_work();
 671
 672         return work && work->func == output_poll_execute;
 673 }
 674 EXPORT_SYMBOL(drm_kms_helper_is_poll_worker);
 675
 676 /**
 677  * drm_kms_helper_poll_disable - disable output polling
 678  * @dev: drm_device
 679  *
 680  * This function disables the output polling work.
 681  *
 682  * Drivers can call this helper from their device suspend implementation. It is
 683  * not an error to call this even when output polling isn't enabled or already
 684  * disabled. Polling is re-enabled by calling drm_kms_helper_poll_enable().
 685  *
 686  * Note that calls to enable and disable polling must be strictly ordered, which
 687  * is automatically the case when they're only call from suspend/resume
 688  * callbacks.
 689  */
 690 void drm_kms_helper_poll_disable(struct drm_device *dev)
 691 {
 692         if (!dev->mode_config.poll_enabled)
 693                 return;
 694         cancel_delayed_work_sync(&dev->mode_config.output_poll_work);
 695 }
 696 EXPORT_SYMBOL(drm_kms_helper_poll_disable);
 697
 698 /**
 699  * drm_kms_helper_poll_init - initialize and enable output polling
 700  * @dev: drm_device
 701  *
 702  * This function intializes and then also enables output polling support for
 703  * @dev. Drivers which do not have reliable hotplug support in hardware can use
 704  * this helper infrastructure to regularly poll such connectors for changes in
 705  * their connection state.
 706  *
 707  * Drivers can control which connectors are polled by setting the
 708  * DRM_CONNECTOR_POLL_CONNECT and DRM_CONNECTOR_POLL_DISCONNECT flags. On
 709  * connectors where probing live outputs can result in visual distortion drivers
 710  * should not set the DRM_CONNECTOR_POLL_DISCONNECT flag to avoid this.
 711  * Connectors which have no flag or only DRM_CONNECTOR_POLL_HPD set are
 712  * completely ignored by the polling logic.
 713  *
 714  * Note that a connector can be both polled and probed from the hotplug handler,
 715  * in case the hotplug interrupt is known to be unreliable.
 716  */
 717 void drm_kms_helper_poll_init(struct drm_device *dev)
 718 {
 719         INIT_DELAYED_WORK(&dev->mode_config.output_poll_work, output_poll_execute);
 720         dev->mode_config.poll_enabled = true;
 721
 722         drm_kms_helper_poll_enable(dev);
 723 }
 724 EXPORT_SYMBOL(drm_kms_helper_poll_init);
 725
 726 /**
 727  * drm_kms_helper_poll_fini - disable output polling and clean it up
 728  * @dev: drm_device
 729  */
 730 void drm_kms_helper_poll_fini(struct drm_device *dev)
 731 {
 732         drm_kms_helper_poll_disable(dev);
 733 }
 734 EXPORT_SYMBOL(drm_kms_helper_poll_fini);
 735
 736 /**
 737  * drm_helper_hpd_irq_event - hotplug processing
 738  * @dev: drm_device
 739  *
 740  * Drivers can use this helper function to run a detect cycle on all connectors
 741  * which have the DRM_CONNECTOR_POLL_HPD flag set in their &polled member. All
 742  * other connectors are ignored, which is useful to avoid reprobing fixed
 743  * panels.
 744  *
 745  * This helper function is useful for drivers which can't or don't track hotplug
 746  * interrupts for each connector.
 747  *
 748  * Drivers which support hotplug interrupts for each connector individually and
 749  * which have a more fine-grained detect logic should bypass this code and
 750  * directly call drm_kms_helper_hotplug_event() in case the connector state
 751  * changed.
 752  *
 753  * This function must be called from process context with no mode
 754  * setting locks held.
 755  *
 756  * Note that a connector can be both polled and probed from the hotplug handler,
 757  * in case the hotplug interrupt is known to be unreliable.
 758  */
 759 bool drm_helper_hpd_irq_event(struct drm_device *dev)
 760 {
 761         struct drm_connector *connector;
 762         struct drm_connector_list_iter conn_iter;
 763         enum drm_connector_status old_status;
 764         bool changed = false;
 765
 766         if (!dev->mode_config.poll_enabled)
 767                 return false;
 768
 769         mutex_lock(&dev->mode_config.mutex);
 770         drm_connector_list_iter_begin(dev, &conn_iter);
 771         drm_for_each_connector_iter(connector, &conn_iter) {
 772                 /* Only handle HPD capable connectors. */
 773                 if (!(connector->polled & DRM_CONNECTOR_POLL_HPD))
 774                         continue;
 775
 776                 old_status = connector->status;
 777
 778                 connector->status = drm_helper_probe_detect(connector, NULL, false);
 779                 DRM_DEBUG_KMS("[CONNECTOR:%d:%s] status updated from %s to %s\n",
 780                               connector->base.id,
 781                               connector->name,
 782                               drm_get_connector_status_name(old_status),
 783                               drm_get_connector_status_name(connector->status));
 784                 if (old_status != connector->status)
 785                         changed = true;
 786         }
 787         drm_connector_list_iter_end(&conn_iter);
 788         mutex_unlock(&dev->mode_config.mutex);
 789
 790         if (changed)
 791                 drm_kms_helper_hotplug_event(dev);
 792
 793         return changed;
 794 }
 795 EXPORT_SYMBOL(drm_helper_hpd_irq_event);