include/drm/drm_modeset_helper_vtables.h

   1 /*
   2  * Copyright © 2006 Keith Packard
   3  * Copyright © 2007-2008 Dave Airlie
   4  * Copyright © 2007-2008 Intel Corporation
   5  *   Jesse Barnes <jesse.barnes@intel.com>
   6  * Copyright © 2011-2013 Intel Corporation
   7  * Copyright © 2015 Intel Corporation
   8  *   Daniel Vetter <daniel.vetter@ffwll.ch>
   9  *
  10  * Permission is hereby granted, free of charge, to any person obtaining a
  11  * copy of this software and associated documentation files (the "Software"),
  12  * to deal in the Software without restriction, including without limitation
  13  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  14  * and/or sell copies of the Software, and to permit persons to whom the
  15  * Software is furnished to do so, subject to the following conditions:
  16  *
  17  * The above copyright notice and this permission notice shall be included in
  18  * all copies or substantial portions of the Software.
  19  *
  20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  23  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  24  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  25  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  26  * OTHER DEALINGS IN THE SOFTWARE.
  27  */
  28
  29 #ifndef __DRM_MODESET_HELPER_VTABLES_H__
  30 #define __DRM_MODESET_HELPER_VTABLES_H__
  31
  32 #include <drm/drm_crtc.h>
  33
  34 /**
  35  * DOC: overview
  36  *
  37  * The DRM mode setting helper functions are common code for drivers to use if
  38  * they wish.  Drivers are not forced to use this code in their
  39  * implementations but it would be useful if the code they do use at least
  40  * provides a consistent interface and operation to userspace. Therefore it is
  41  * highly recommended to use the provided helpers as much as possible.
  42  *
  43  * Because there is only one pointer per modeset object to hold a vfunc table
  44  * for helper libraries they are by necessity shared among the different
  45  * helpers.
  46  *
  47  * To make this clear all the helper vtables are pulled together in this location here.
  48  */
  49
  50 enum mode_set_atomic;
  51
  52 /**
  53  * struct drm_crtc_helper_funcs - helper operations for CRTCs
  54  *
  55  * These hooks are used by the legacy CRTC helpers, the transitional plane
  56  * helpers and the new atomic modesetting helpers.
  57  */
  58 struct drm_crtc_helper_funcs {
  59         /**
  60          * @dpms:
  61          *
  62          * Callback to control power levels on the CRTC.  If the mode passed in
  63          * is unsupported, the provider must use the next lowest power level.
  64          * This is used by the legacy CRTC helpers to implement DPMS
  65          * functionality in drm_helper_connector_dpms().
  66          *
  67          * This callback is also used to disable a CRTC by calling it with
  68          * DRM_MODE_DPMS_OFF if the @disable hook isn't used.
  69          *
  70          * This callback is used by the legacy CRTC helpers.  Atomic helpers
  71          * also support using this hook for enabling and disabling a CRTC to
  72          * facilitate transitions to atomic, but it is deprecated. Instead
  73          * @enable and @disable should be used.
  74          */
  75         void (*dpms)(struct drm_crtc *crtc, int mode);
  76
  77         /**
  78          * @prepare:
  79          *
  80          * This callback should prepare the CRTC for a subsequent modeset, which
  81          * in practice means the driver should disable the CRTC if it is
  82          * running. Most drivers ended up implementing this by calling their
  83          * @dpms hook with DRM_MODE_DPMS_OFF.
  84          *
  85          * This callback is used by the legacy CRTC helpers.  Atomic helpers
  86          * also support using this hook for disabling a CRTC to facilitate
  87          * transitions to atomic, but it is deprecated. Instead @disable should
  88          * be used.
  89          */
  90         void (*prepare)(struct drm_crtc *crtc);
  91
  92         /**
  93          * @commit:
  94          *
  95          * This callback should commit the new mode on the CRTC after a modeset,
  96          * which in practice means the driver should enable the CRTC.  Most
  97          * drivers ended up implementing this by calling their @dpms hook with
  98          * DRM_MODE_DPMS_ON.
  99          *
 100          * This callback is used by the legacy CRTC helpers.  Atomic helpers
 101          * also support using this hook for enabling a CRTC to facilitate
 102          * transitions to atomic, but it is deprecated. Instead @enable should
 103          * be used.
 104          */
 105         void (*commit)(struct drm_crtc *crtc);
 106
 107         /**
 108          * @mode_fixup:
 109          *
 110          * This callback is used to validate a mode. The parameter mode is the
 111          * display mode that userspace requested, adjusted_mode is the mode the
 112          * encoders need to be fed with. Note that this is the inverse semantics
 113          * of the meaning for the &drm_encoder and &drm_bridge
 114          * ->mode_fixup() functions. If the CRTC cannot support the requested
 115          * conversion from mode to adjusted_mode it should reject the modeset.
 116          *
 117          * This function is used by both legacy CRTC helpers and atomic helpers.
 118          * With atomic helpers it is optional.
 119          *
 120          * NOTE:
 121          *
 122          * This function is called in the check phase of atomic modesets, which
 123          * can be aborted for any reason (including on userspace's request to
 124          * just check whether a configuration would be possible). Atomic drivers
 125          * MUST NOT touch any persistent state (hardware or software) or data
 126          * structures except the passed in adjusted_mode parameter.
 127          *
 128          * This is in contrast to the legacy CRTC helpers where this was
 129          * allowed.
 130          *
 131          * Atomic drivers which need to inspect and adjust more state should
 132          * instead use the @atomic_check callback.
 133          *
 134          * Also beware that neither core nor helpers filter modes before
 135          * passing them to the driver: While the list of modes that is
 136          * advertised to userspace is filtered using the connector's
 137          * ->mode_valid() callback, neither the core nor the helpers do any
 138          * filtering on modes passed in from userspace when setting a mode. It
 139          * is therefore possible for userspace to pass in a mode that was
 140          * previously filtered out using ->mode_valid() or add a custom mode
 141          * that wasn't probed from EDID or similar to begin with.  Even though
 142          * this is an advanced feature and rarely used nowadays, some users rely
 143          * on being able to specify modes manually so drivers must be prepared
 144          * to deal with it. Specifically this means that all drivers need not
 145          * only validate modes in ->mode_valid() but also in ->mode_fixup() to
 146          * make sure invalid modes passed in from userspace are rejected.
 147          *
 148          * RETURNS:
 149          *
 150          * True if an acceptable configuration is possible, false if the modeset
 151          * operation should be rejected.
 152          */
 153         bool (*mode_fixup)(struct drm_crtc *crtc,
 154                            const struct drm_display_mode *mode,
 155                            struct drm_display_mode *adjusted_mode);
 156
 157         /**
 158          * @mode_set:
 159          *
 160          * This callback is used by the legacy CRTC helpers to set a new mode,
 161          * position and framebuffer. Since it ties the primary plane to every
 162          * mode change it is incompatible with universal plane support. And
 163          * since it can't update other planes it's incompatible with atomic
 164          * modeset support.
 165          *
 166          * This callback is only used by CRTC helpers and deprecated.
 167          *
 168          * RETURNS:
 169          *
 170          * 0 on success or a negative error code on failure.
 171          */
 172         int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode,
 173                         struct drm_display_mode *adjusted_mode, int x, int y,
 174                         struct drm_framebuffer *old_fb);
 175
 176         /**
 177          * @mode_set_nofb:
 178          *
 179          * This callback is used to update the display mode of a CRTC without
 180          * changing anything of the primary plane configuration. This fits the
 181          * requirement of atomic and hence is used by the atomic helpers. It is
 182          * also used by the transitional plane helpers to implement a
 183          * @mode_set hook in drm_helper_crtc_mode_set().
 184          *
 185          * Note that the display pipe is completely off when this function is
 186          * called. Atomic drivers which need hardware to be running before they
 187          * program the new display mode (e.g. because they implement runtime PM)
 188          * should not use this hook. This is because the helper library calls
 189          * this hook only once per mode change and not every time the display
 190          * pipeline is suspended using either DPMS or the new "ACTIVE" property.
 191          * Which means register values set in this callback might get reset when
 192          * the CRTC is suspended, but not restored.  Such drivers should instead
 193          * move all their CRTC setup into the @enable callback.
 194          *
 195          * This callback is optional.
 196          */
 197         void (*mode_set_nofb)(struct drm_crtc *crtc);
 198
 199         /**
 200          * @mode_set_base:
 201          *
 202          * This callback is used by the legacy CRTC helpers to set a new
 203          * framebuffer and scanout position. It is optional and used as an
 204          * optimized fast-path instead of a full mode set operation with all the
 205          * resulting flickering. If it is not present
 206          * drm_crtc_helper_set_config() will fall back to a full modeset, using
 207          * the ->mode_set() callback. Since it can't update other planes it's
 208          * incompatible with atomic modeset support.
 209          *
 210          * This callback is only used by the CRTC helpers and deprecated.
 211          *
 212          * RETURNS:
 213          *
 214          * 0 on success or a negative error code on failure.
 215          */
 216         int (*mode_set_base)(struct drm_crtc *crtc, int x, int y,
 217                              struct drm_framebuffer *old_fb);
 218
 219         /**
 220          * @mode_set_base_atomic:
 221          *
 222          * This callback is used by the fbdev helpers to set a new framebuffer
 223          * and scanout without sleeping, i.e. from an atomic calling context. It
 224          * is only used to implement kgdb support.
 225          *
 226          * This callback is optional and only needed for kgdb support in the fbdev
 227          * helpers.
 228          *
 229          * RETURNS:
 230          *
 231          * 0 on success or a negative error code on failure.
 232          */
 233         int (*mode_set_base_atomic)(struct drm_crtc *crtc,
 234                                     struct drm_framebuffer *fb, int x, int y,
 235                                     enum mode_set_atomic);
 236
 237         /**
 238          * @load_lut:
 239          *
 240          * Load a LUT prepared with the @gamma_set functions from
 241          * &drm_fb_helper_funcs.
 242          *
 243          * This callback is optional and is only used by the fbdev emulation
 244          * helpers.
 245          *
 246          * FIXME:
 247          *
 248          * This callback is functionally redundant with the core gamma table
 249          * support and simply exists because the fbdev hasn't yet been
 250          * refactored to use the core gamma table interfaces.
 251          */
 252         void (*load_lut)(struct drm_crtc *crtc);
 253
 254         /**
 255          * @disable:
 256          *
 257          * This callback should be used to disable the CRTC. With the atomic
 258          * drivers it is called after all encoders connected to this CRTC have
 259          * been shut off already using their own ->disable hook. If that
 260          * sequence is too simple drivers can just add their own hooks and call
 261          * it from this CRTC callback here by looping over all encoders
 262          * connected to it using for_each_encoder_on_crtc().
 263          *
 264          * This hook is used both by legacy CRTC helpers and atomic helpers.
 265          * Atomic drivers don't need to implement it if there's no need to
 266          * disable anything at the CRTC level. To ensure that runtime PM
 267          * handling (using either DPMS or the new "ACTIVE" property) works
 268          * @disable must be the inverse of @enable for atomic drivers.
 269          *
 270          * NOTE:
 271          *
 272          * With legacy CRTC helpers there's a big semantic difference between
 273          * @disable and other hooks (like @prepare or @dpms) used to shut down a
 274          * CRTC: @disable is only called when also logically disabling the
 275          * display pipeline and needs to release any resources acquired in
 276          * @mode_set (like shared PLLs, or again release pinned framebuffers).
 277          *
 278          * Therefore @disable must be the inverse of @mode_set plus @commit for
 279          * drivers still using legacy CRTC helpers, which is different from the
 280          * rules under atomic.
 281          */
 282         void (*disable)(struct drm_crtc *crtc);
 283
 284         /**
 285          * @enable:
 286          *
 287          * This callback should be used to enable the CRTC. With the atomic
 288          * drivers it is called before all encoders connected to this CRTC are
 289          * enabled through the encoder's own ->enable hook.  If that sequence is
 290          * too simple drivers can just add their own hooks and call it from this
 291          * CRTC callback here by looping over all encoders connected to it using
 292          * for_each_encoder_on_crtc().
 293          *
 294          * This hook is used only by atomic helpers, for symmetry with @disable.
 295          * Atomic drivers don't need to implement it if there's no need to
 296          * enable anything at the CRTC level. To ensure that runtime PM handling
 297          * (using either DPMS or the new "ACTIVE" property) works
 298          * @enable must be the inverse of @disable for atomic drivers.
 299          */
 300         void (*enable)(struct drm_crtc *crtc);
 301
 302         /**
 303          * @atomic_check:
 304          *
 305          * Drivers should check plane-update related CRTC constraints in this
 306          * hook. They can also check mode related limitations but need to be
 307          * aware of the calling order, since this hook is used by
 308          * drm_atomic_helper_check_planes() whereas the preparations needed to
 309          * check output routing and the display mode is done in
 310          * drm_atomic_helper_check_modeset(). Therefore drivers that want to
 311          * check output routing and display mode constraints in this callback
 312          * must ensure that drm_atomic_helper_check_modeset() has been called
 313          * beforehand. This is calling order used by the default helper
 314          * implementation in drm_atomic_helper_check().
 315          *
 316          * When using drm_atomic_helper_check_planes() CRTCs' ->atomic_check()
 317          * hooks are called after the ones for planes, which allows drivers to
 318          * assign shared resources requested by planes in the CRTC callback
 319          * here. For more complicated dependencies the driver can call the provided
 320          * check helpers multiple times until the computed state has a final
 321          * configuration and everything has been checked.
 322          *
 323          * This function is also allowed to inspect any other object's state and
 324          * can add more state objects to the atomic commit if needed. Care must
 325          * be taken though to ensure that state check&compute functions for
 326          * these added states are all called, and derived state in other objects
 327          * all updated. Again the recommendation is to just call check helpers
 328          * until a maximal configuration is reached.
 329          *
 330          * This callback is used by the atomic modeset helpers and by the
 331          * transitional plane helpers, but it is optional.
 332          *
 333          * NOTE:
 334          *
 335          * This function is called in the check phase of an atomic update. The
 336          * driver is not allowed to change anything outside of the free-standing
 337          * state objects passed-in or assembled in the overall &drm_atomic_state
 338          * update tracking structure.
 339          *
 340          * RETURNS:
 341          *
 342          * 0 on success, -EINVAL if the state or the transition can't be
 343          * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
 344          * attempt to obtain another state object ran into a &drm_modeset_lock
 345          * deadlock.
 346          */
 347         int (*atomic_check)(struct drm_crtc *crtc,
 348                             struct drm_crtc_state *state);
 349
 350         /**
 351          * @atomic_begin:
 352          *
 353          * Drivers should prepare for an atomic update of multiple planes on
 354          * a CRTC in this hook. Depending upon hardware this might be vblank
 355          * evasion, blocking updates by setting bits or doing preparatory work
 356          * for e.g. manual update display.
 357          *
 358          * This hook is called before any plane commit functions are called.
 359          *
 360          * Note that the power state of the display pipe when this function is
 361          * called depends upon the exact helpers and calling sequence the driver
 362          * has picked. See drm_atomic_commit_planes() for a discussion of the
 363          * tradeoffs and variants of plane commit helpers.
 364          *
 365          * This callback is used by the atomic modeset helpers and by the
 366          * transitional plane helpers, but it is optional.
 367          */
 368         void (*atomic_begin)(struct drm_crtc *crtc,
 369                              struct drm_crtc_state *old_crtc_state);
 370         /**
 371          * @atomic_flush:
 372          *
 373          * Drivers should finalize an atomic update of multiple planes on
 374          * a CRTC in this hook. Depending upon hardware this might include
 375          * checking that vblank evasion was successful, unblocking updates by
 376          * setting bits or setting the GO bit to flush out all updates.
 377          *
 378          * Simple hardware or hardware with special requirements can commit and
 379          * flush out all updates for all planes from this hook and forgo all the
 380          * other commit hooks for plane updates.
 381          *
 382          * This hook is called after any plane commit functions are called.
 383          *
 384          * Note that the power state of the display pipe when this function is
 385          * called depends upon the exact helpers and calling sequence the driver
 386          * has picked. See drm_atomic_commit_planes() for a discussion of the
 387          * tradeoffs and variants of plane commit helpers.
 388          *
 389          * This callback is used by the atomic modeset helpers and by the
 390          * transitional plane helpers, but it is optional.
 391          */
 392         void (*atomic_flush)(struct drm_crtc *crtc,
 393                              struct drm_crtc_state *old_crtc_state);
 394 };
 395
 396 /**
 397  * drm_crtc_helper_add - sets the helper vtable for a crtc
 398  * @crtc: DRM CRTC
 399  * @funcs: helper vtable to set for @crtc
 400  */
 401 static inline void drm_crtc_helper_add(struct drm_crtc *crtc,
 402                                        const struct drm_crtc_helper_funcs *funcs)
 403 {
 404         crtc->helper_private = funcs;
 405 }
 406
 407 /**
 408  * struct drm_encoder_helper_funcs - helper operations for encoders
 409  *
 410  * These hooks are used by the legacy CRTC helpers, the transitional plane
 411  * helpers and the new atomic modesetting helpers.
 412  */
 413 struct drm_encoder_helper_funcs {
 414         /**
 415          * @dpms:
 416          *
 417          * Callback to control power levels on the encoder.  If the mode passed in
 418          * is unsupported, the provider must use the next lowest power level.
 419          * This is used by the legacy encoder helpers to implement DPMS
 420          * functionality in drm_helper_connector_dpms().
 421          *
 422          * This callback is also used to disable an encoder by calling it with
 423          * DRM_MODE_DPMS_OFF if the @disable hook isn't used.
 424          *
 425          * This callback is used by the legacy CRTC helpers.  Atomic helpers
 426          * also support using this hook for enabling and disabling an encoder to
 427          * facilitate transitions to atomic, but it is deprecated. Instead
 428          * @enable and @disable should be used.
 429          */
 430         void (*dpms)(struct drm_encoder *encoder, int mode);
 431
 432         /**
 433          * @mode_fixup:
 434          *
 435          * This callback is used to validate and adjust a mode. The parameter
 436          * mode is the display mode that should be fed to the next element in
 437          * the display chain, either the final &drm_connector or a &drm_bridge.
 438          * The parameter adjusted_mode is the input mode the encoder requires. It
 439          * can be modified by this callback and does not need to match mode.
 440          *
 441          * This function is used by both legacy CRTC helpers and atomic helpers.
 442          * This hook is optional.
 443          *
 444          * NOTE:
 445          *
 446          * This function is called in the check phase of atomic modesets, which
 447          * can be aborted for any reason (including on userspace's request to
 448          * just check whether a configuration would be possible). Atomic drivers
 449          * MUST NOT touch any persistent state (hardware or software) or data
 450          * structures except the passed in adjusted_mode parameter.
 451          *
 452          * This is in contrast to the legacy CRTC helpers where this was
 453          * allowed.
 454          *
 455          * Atomic drivers which need to inspect and adjust more state should
 456          * instead use the @atomic_check callback.
 457          *
 458          * Also beware that neither core nor helpers filter modes before
 459          * passing them to the driver: While the list of modes that is
 460          * advertised to userspace is filtered using the connector's
 461          * ->mode_valid() callback, neither the core nor the helpers do any
 462          * filtering on modes passed in from userspace when setting a mode. It
 463          * is therefore possible for userspace to pass in a mode that was
 464          * previously filtered out using ->mode_valid() or add a custom mode
 465          * that wasn't probed from EDID or similar to begin with.  Even though
 466          * this is an advanced feature and rarely used nowadays, some users rely
 467          * on being able to specify modes manually so drivers must be prepared
 468          * to deal with it. Specifically this means that all drivers need not
 469          * only validate modes in ->mode_valid() but also in ->mode_fixup() to
 470          * make sure invalid modes passed in from userspace are rejected.
 471          *
 472          * RETURNS:
 473          *
 474          * True if an acceptable configuration is possible, false if the modeset
 475          * operation should be rejected.
 476          */
 477         bool (*mode_fixup)(struct drm_encoder *encoder,
 478                            const struct drm_display_mode *mode,
 479                            struct drm_display_mode *adjusted_mode);
 480
 481         /**
 482          * @prepare:
 483          *
 484          * This callback should prepare the encoder for a subsequent modeset,
 485          * which in practice means the driver should disable the encoder if it
 486          * is running. Most drivers ended up implementing this by calling their
 487          * @dpms hook with DRM_MODE_DPMS_OFF.
 488          *
 489          * This callback is used by the legacy CRTC helpers.  Atomic helpers
 490          * also support using this hook for disabling an encoder to facilitate
 491          * transitions to atomic, but it is deprecated. Instead @disable should
 492          * be used.
 493          */
 494         void (*prepare)(struct drm_encoder *encoder);
 495
 496         /**
 497          * @commit:
 498          *
 499          * This callback should commit the new mode on the encoder after a modeset,
 500          * which in practice means the driver should enable the encoder.  Most
 501          * drivers ended up implementing this by calling their @dpms hook with
 502          * DRM_MODE_DPMS_ON.
 503          *
 504          * This callback is used by the legacy CRTC helpers.  Atomic helpers
 505          * also support using this hook for enabling an encoder to facilitate
 506          * transitions to atomic, but it is deprecated. Instead @enable should
 507          * be used.
 508          */
 509         void (*commit)(struct drm_encoder *encoder);
 510
 511         /**
 512          * @mode_set:
 513          *
 514          * This callback is used to update the display mode of an encoder.
 515          *
 516          * Note that the display pipe is completely off when this function is
 517          * called. Drivers which need hardware to be running before they program
 518          * the new display mode (because they implement runtime PM) should not
 519          * use this hook, because the helper library calls it only once and not
 520          * every time the display pipeline is suspend using either DPMS or the
 521          * new "ACTIVE" property. Such drivers should instead move all their
 522          * encoder setup into the ->enable() callback.
 523          *
 524          * This callback is used both by the legacy CRTC helpers and the atomic
 525          * modeset helpers. It is optional in the atomic helpers.
 526          */
 527         void (*mode_set)(struct drm_encoder *encoder,
 528                          struct drm_display_mode *mode,
 529                          struct drm_display_mode *adjusted_mode);
 530
 531         /**
 532          * @get_crtc:
 533          *
 534          * This callback is used by the legacy CRTC helpers to work around
 535          * deficiencies in its own book-keeping.
 536          *
 537          * Do not use, use atomic helpers instead, which get the book keeping
 538          * right.
 539          *
 540          * FIXME:
 541          *
 542          * Currently only nouveau is using this, and as soon as nouveau is
 543          * atomic we can ditch this hook.
 544          */
 545         struct drm_crtc *(*get_crtc)(struct drm_encoder *encoder);
 546
 547         /**
 548          * @detect:
 549          *
 550          * This callback can be used by drivers who want to do detection on the
 551          * encoder object instead of in connector functions.
 552          *
 553          * It is not used by any helper and therefore has purely driver-specific
 554          * semantics. New drivers shouldn't use this and instead just implement
 555          * their own private callbacks.
 556          *
 557          * FIXME:
 558          *
 559          * This should just be converted into a pile of driver vfuncs.
 560          * Currently radeon, amdgpu and nouveau are using it.
 561          */
 562         enum drm_connector_status (*detect)(struct drm_encoder *encoder,
 563                                             struct drm_connector *connector);
 564
 565         /**
 566          * @disable:
 567          *
 568          * This callback should be used to disable the encoder. With the atomic
 569          * drivers it is called before this encoder's CRTC has been shut off
 570          * using the CRTC's own ->disable hook.  If that sequence is too simple
 571          * drivers can just add their own driver private encoder hooks and call
 572          * them from CRTC's callback by looping over all encoders connected to
 573          * it using for_each_encoder_on_crtc().
 574          *
 575          * This hook is used both by legacy CRTC helpers and atomic helpers.
 576          * Atomic drivers don't need to implement it if there's no need to
 577          * disable anything at the encoder level. To ensure that runtime PM
 578          * handling (using either DPMS or the new "ACTIVE" property) works
 579          * @disable must be the inverse of @enable for atomic drivers.
 580          *
 581          * NOTE:
 582          *
 583          * With legacy CRTC helpers there's a big semantic difference between
 584          * @disable and other hooks (like @prepare or @dpms) used to shut down a
 585          * encoder: @disable is only called when also logically disabling the
 586          * display pipeline and needs to release any resources acquired in
 587          * @mode_set (like shared PLLs, or again release pinned framebuffers).
 588          *
 589          * Therefore @disable must be the inverse of @mode_set plus @commit for
 590          * drivers still using legacy CRTC helpers, which is different from the
 591          * rules under atomic.
 592          */
 593         void (*disable)(struct drm_encoder *encoder);
 594
 595         /**
 596          * @enable:
 597          *
 598          * This callback should be used to enable the encoder. With the atomic
 599          * drivers it is called after this encoder's CRTC has been enabled using
 600          * the CRTC's own ->enable hook.  If that sequence is too simple drivers
 601          * can just add their own driver private encoder hooks and call them
 602          * from CRTC's callback by looping over all encoders connected to it
 603          * using for_each_encoder_on_crtc().
 604          *
 605          * This hook is used only by atomic helpers, for symmetry with @disable.
 606          * Atomic drivers don't need to implement it if there's no need to
 607          * enable anything at the encoder level. To ensure that runtime PM handling
 608          * (using either DPMS or the new "ACTIVE" property) works
 609          * @enable must be the inverse of @disable for atomic drivers.
 610          */
 611         void (*enable)(struct drm_encoder *encoder);
 612
 613         /**
 614          * @atomic_check:
 615          *
 616          * This callback is used to validate encoder state for atomic drivers.
 617          * Since the encoder is the object connecting the CRTC and connector it
 618          * gets passed both states, to be able to validate interactions and
 619          * update the CRTC to match what the encoder needs for the requested
 620          * connector.
 621          *
 622          * This function is used by the atomic helpers, but it is optional.
 623          *
 624          * NOTE:
 625          *
 626          * This function is called in the check phase of an atomic update. The
 627          * driver is not allowed to change anything outside of the free-standing
 628          * state objects passed-in or assembled in the overall &drm_atomic_state
 629          * update tracking structure.
 630          *
 631          * RETURNS:
 632          *
 633          * 0 on success, -EINVAL if the state or the transition can't be
 634          * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
 635          * attempt to obtain another state object ran into a &drm_modeset_lock
 636          * deadlock.
 637          */
 638         int (*atomic_check)(struct drm_encoder *encoder,
 639                             struct drm_crtc_state *crtc_state,
 640                             struct drm_connector_state *conn_state);
 641 };
 642
 643 /**
 644  * drm_encoder_helper_add - sets the helper vtable for an encoder
 645  * @encoder: DRM encoder
 646  * @funcs: helper vtable to set for @encoder
 647  */
 648 static inline void drm_encoder_helper_add(struct drm_encoder *encoder,
 649                                           const struct drm_encoder_helper_funcs *funcs)
 650 {
 651         encoder->helper_private = funcs;
 652 }
 653
 654 /**
 655  * struct drm_connector_helper_funcs - helper operations for connectors
 656  *
 657  * These functions are used by the atomic and legacy modeset helpers and by the
 658  * probe helpers.
 659  */
 660 struct drm_connector_helper_funcs {
 661         /**
 662          * @get_modes:
 663          *
 664          * This function should fill in all modes currently valid for the sink
 665          * into the connector->probed_modes list. It should also update the
 666          * EDID property by calling drm_mode_connector_update_edid_property().
 667          *
 668          * The usual way to implement this is to cache the EDID retrieved in the
 669          * probe callback somewhere in the driver-private connector structure.
 670          * In this function drivers then parse the modes in the EDID and add
 671          * them by calling drm_add_edid_modes(). But connectors that driver a
 672          * fixed panel can also manually add specific modes using
 673          * drm_mode_probed_add(). Drivers which manually add modes should also
 674          * make sure that the @display_info, @width_mm and @height_mm fields of the
 675          * struct &drm_connector are filled in.
 676          *
 677          * Virtual drivers that just want some standard VESA mode with a given
 678          * resolution can call drm_add_modes_noedid(), and mark the preferred
 679          * one using drm_set_preferred_mode().
 680          *
 681          * Finally drivers that support audio probably want to update the ELD
 682          * data, too, using drm_edid_to_eld().
 683          *
 684          * This function is only called after the ->detect() hook has indicated
 685          * that a sink is connected and when the EDID isn't overridden through
 686          * sysfs or the kernel commandline.
 687          *
 688          * This callback is used by the probe helpers in e.g.
 689          * drm_helper_probe_single_connector_modes().
 690          *
 691          * RETURNS:
 692          *
 693          * The number of modes added by calling drm_mode_probed_add().
 694          */
 695         int (*get_modes)(struct drm_connector *connector);
 696
 697         /**
 698          * @mode_valid:
 699          *
 700          * Callback to validate a mode for a connector, irrespective of the
 701          * specific display configuration.
 702          *
 703          * This callback is used by the probe helpers to filter the mode list
 704          * (which is usually derived from the EDID data block from the sink).
 705          * See e.g. drm_helper_probe_single_connector_modes().
 706          *
 707          * NOTE:
 708          *
 709          * This only filters the mode list supplied to userspace in the
 710          * GETCONNECOTR IOCTL. Userspace is free to create modes of its own and
 711          * ask the kernel to use them. It this case the atomic helpers or legacy
 712          * CRTC helpers will not call this function. Drivers therefore must
 713          * still fully validate any mode passed in in a modeset request.
 714          *
 715          * RETURNS:
 716          *
 717          * Either MODE_OK or one of the failure reasons in enum
 718          * &drm_mode_status.
 719          */
 720         enum drm_mode_status (*mode_valid)(struct drm_connector *connector,
 721                                            struct drm_display_mode *mode);
 722         /**
 723          * @best_encoder:
 724          *
 725          * This function should select the best encoder for the given connector.
 726          *
 727          * This function is used by both the atomic helpers (in the
 728          * drm_atomic_helper_check_modeset() function) and in the legacy CRTC
 729          * helpers.
 730          *
 731          * NOTE:
 732          *
 733          * In atomic drivers this function is called in the check phase of an
 734          * atomic update. The driver is not allowed to change or inspect
 735          * anything outside of arguments passed-in. Atomic drivers which need to
 736          * inspect dynamic configuration state should instead use
 737          * @atomic_best_encoder.
 738          *
 739          * You can leave this function to NULL if the connector is only
 740          * attached to a single encoder and you are using the atomic helpers.
 741          * In this case, the core will call drm_atomic_helper_best_encoder()
 742          * for you.
 743          *
 744          * RETURNS:
 745          *
 746          * Encoder that should be used for the given connector and connector
 747          * state, or NULL if no suitable encoder exists. Note that the helpers
 748          * will ensure that encoders aren't used twice, drivers should not check
 749          * for this.
 750          */
 751         struct drm_encoder *(*best_encoder)(struct drm_connector *connector);
 752
 753         /**
 754          * @atomic_best_encoder:
 755          *
 756          * This is the atomic version of @best_encoder for atomic drivers which
 757          * need to select the best encoder depending upon the desired
 758          * configuration and can't select it statically.
 759          *
 760          * This function is used by drm_atomic_helper_check_modeset().
 761          * If it is not implemented, the core will fallback to @best_encoder
 762          * (or drm_atomic_helper_best_encoder() if @best_encoder is NULL).
 763          *
 764          * NOTE:
 765          *
 766          * This function is called in the check phase of an atomic update. The
 767          * driver is not allowed to change anything outside of the free-standing
 768          * state objects passed-in or assembled in the overall &drm_atomic_state
 769          * update tracking structure.
 770          *
 771          * RETURNS:
 772          *
 773          * Encoder that should be used for the given connector and connector
 774          * state, or NULL if no suitable encoder exists. Note that the helpers
 775          * will ensure that encoders aren't used twice, drivers should not check
 776          * for this.
 777          */
 778         struct drm_encoder *(*atomic_best_encoder)(struct drm_connector *connector,
 779                                                    struct drm_connector_state *connector_state);
 780 };
 781
 782 /**
 783  * drm_connector_helper_add - sets the helper vtable for a connector
 784  * @connector: DRM connector
 785  * @funcs: helper vtable to set for @connector
 786  */
 787 static inline void drm_connector_helper_add(struct drm_connector *connector,
 788                                             const struct drm_connector_helper_funcs *funcs)
 789 {
 790         connector->helper_private = funcs;
 791 }
 792
 793 /**
 794  * struct drm_plane_helper_funcs - helper operations for planes
 795  *
 796  * These functions are used by the atomic helpers and by the transitional plane
 797  * helpers.
 798  */
 799 struct drm_plane_helper_funcs {
 800         /**
 801          * @prepare_fb:
 802          *
 803          * This hook is to prepare a framebuffer for scanout by e.g. pinning
 804          * it's backing storage or relocating it into a contiguous block of
 805          * VRAM. Other possible preparatory work includes flushing caches.
 806          *
 807          * This function must not block for outstanding rendering, since it is
 808          * called in the context of the atomic IOCTL even for async commits to
 809          * be able to return any errors to userspace. Instead the recommended
 810          * way is to fill out the fence member of the passed-in
 811          * &drm_plane_state. If the driver doesn't support native fences then
 812          * equivalent functionality should be implemented through private
 813          * members in the plane structure.
 814          *
 815          * The helpers will call @cleanup_fb with matching arguments for every
 816          * successful call to this hook.
 817          *
 818          * This callback is used by the atomic modeset helpers and by the
 819          * transitional plane helpers, but it is optional.
 820          *
 821          * RETURNS:
 822          *
 823          * 0 on success or one of the following negative error codes allowed by
 824          * the atomic_commit hook in &drm_mode_config_funcs. When using helpers
 825          * this callback is the only one which can fail an atomic commit,
 826          * everything else must complete successfully.
 827          */
 828         int (*prepare_fb)(struct drm_plane *plane,
 829                           const struct drm_plane_state *new_state);
 830         /**
 831          * @cleanup_fb:
 832          *
 833          * This hook is called to clean up any resources allocated for the given
 834          * framebuffer and plane configuration in @prepare_fb.
 835          *
 836          * This callback is used by the atomic modeset helpers and by the
 837          * transitional plane helpers, but it is optional.
 838          */
 839         void (*cleanup_fb)(struct drm_plane *plane,
 840                            const struct drm_plane_state *old_state);
 841
 842         /**
 843          * @atomic_check:
 844          *
 845          * Drivers should check plane specific constraints in this hook.
 846          *
 847          * When using drm_atomic_helper_check_planes() plane's ->atomic_check()
 848          * hooks are called before the ones for CRTCs, which allows drivers to
 849          * request shared resources that the CRTC controls here. For more
 850          * complicated dependencies the driver can call the provided check helpers
 851          * multiple times until the computed state has a final configuration and
 852          * everything has been checked.
 853          *
 854          * This function is also allowed to inspect any other object's state and
 855          * can add more state objects to the atomic commit if needed. Care must
 856          * be taken though to ensure that state check&compute functions for
 857          * these added states are all called, and derived state in other objects
 858          * all updated. Again the recommendation is to just call check helpers
 859          * until a maximal configuration is reached.
 860          *
 861          * This callback is used by the atomic modeset helpers and by the
 862          * transitional plane helpers, but it is optional.
 863          *
 864          * NOTE:
 865          *
 866          * This function is called in the check phase of an atomic update. The
 867          * driver is not allowed to change anything outside of the free-standing
 868          * state objects passed-in or assembled in the overall &drm_atomic_state
 869          * update tracking structure.
 870          *
 871          * RETURNS:
 872          *
 873          * 0 on success, -EINVAL if the state or the transition can't be
 874          * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
 875          * attempt to obtain another state object ran into a &drm_modeset_lock
 876          * deadlock.
 877          */
 878         int (*atomic_check)(struct drm_plane *plane,
 879                             struct drm_plane_state *state);
 880
 881         /**
 882          * @atomic_update:
 883          *
 884          * Drivers should use this function to update the plane state.  This
 885          * hook is called in-between the ->atomic_begin() and
 886          * ->atomic_flush() of &drm_crtc_helper_funcs.
 887          *
 888          * Note that the power state of the display pipe when this function is
 889          * called depends upon the exact helpers and calling sequence the driver
 890          * has picked. See drm_atomic_commit_planes() for a discussion of the
 891          * tradeoffs and variants of plane commit helpers.
 892          *
 893          * This callback is used by the atomic modeset helpers and by the
 894          * transitional plane helpers, but it is optional.
 895          */
 896         void (*atomic_update)(struct drm_plane *plane,
 897                               struct drm_plane_state *old_state);
 898         /**
 899          * @atomic_disable:
 900          *
 901          * Drivers should use this function to unconditionally disable a plane.
 902          * This hook is called in-between the ->atomic_begin() and
 903          * ->atomic_flush() of &drm_crtc_helper_funcs. It is an alternative to
 904          * @atomic_update, which will be called for disabling planes, too, if
 905          * the @atomic_disable hook isn't implemented.
 906          *
 907          * This hook is also useful to disable planes in preparation of a modeset,
 908          * by calling drm_atomic_helper_disable_planes_on_crtc() from the
 909          * ->disable() hook in &drm_crtc_helper_funcs.
 910          *
 911          * Note that the power state of the display pipe when this function is
 912          * called depends upon the exact helpers and calling sequence the driver
 913          * has picked. See drm_atomic_commit_planes() for a discussion of the
 914          * tradeoffs and variants of plane commit helpers.
 915          *
 916          * This callback is used by the atomic modeset helpers and by the
 917          * transitional plane helpers, but it is optional.
 918          */
 919         void (*atomic_disable)(struct drm_plane *plane,
 920                                struct drm_plane_state *old_state);
 921 };
 922
 923 /**
 924  * drm_plane_helper_add - sets the helper vtable for a plane
 925  * @plane: DRM plane
 926  * @funcs: helper vtable to set for @plane
 927  */
 928 static inline void drm_plane_helper_add(struct drm_plane *plane,
 929                                         const struct drm_plane_helper_funcs *funcs)
 930 {
 931         plane->helper_private = funcs;
 932 }
 933
 934 /**
 935  * struct drm_mode_config_helper_funcs - global modeset helper operations
 936  *
 937  * These helper functions are used by the atomic helpers.
 938  */
 939 struct drm_mode_config_helper_funcs {
 940         /**
 941          * @atomic_commit_tail:
 942          *
 943          * This hook is used by the default atomic_commit() hook implemented in
 944          * drm_atomic_helper_commit() together with the nonblocking commit
 945          * helpers (see drm_atomic_helper_setup_commit() for a starting point)
 946          * to implement blocking and nonblocking commits easily. It is not used
 947          * by the atomic helpers
 948          *
 949          * This hook should first commit the given atomic state to the hardware.
 950          * But drivers can add more waiting calls at the start of their
 951          * implementation, e.g. to wait for driver-internal request for implicit
 952          * syncing, before starting to commit the update to the hardware.
 953          *
 954          * After the atomic update is committed to the hardware this hook needs
 955          * to call drm_atomic_helper_commit_hw_done(). Then wait for the upate
 956          * to be executed by the hardware, for example using
 957          * drm_atomic_helper_wait_for_vblanks(), and then clean up the old
 958          * framebuffers using drm_atomic_helper_cleanup_planes().
 959          *
 960          * When disabling a CRTC this hook _must_ stall for the commit to
 961          * complete. Vblank waits don't work on disabled CRTC, hence the core
 962          * can't take care of this. And it also can't rely on the vblank event,
 963          * since that can be signalled already when the screen shows black,
 964          * which can happen much earlier than the last hardware access needed to
 965          * shut off the display pipeline completely.
 966          *
 967          * This hook is optional, the default implementation is
 968          * drm_atomic_helper_commit_tail().
 969          */
 970         void (*atomic_commit_tail)(struct drm_atomic_state *state);
 971 };
 972
 973 #endif