xref: /linux/include/drm/drm_modeset_helper_vtables.h (revision 1f2367a39f17bd553a75e179a747f9b257bc9478)
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 #include <drm/drm_encoder.h>
34 
35 /**
36  * DOC: overview
37  *
38  * The DRM mode setting helper functions are common code for drivers to use if
39  * they wish.  Drivers are not forced to use this code in their
40  * implementations but it would be useful if the code they do use at least
41  * provides a consistent interface and operation to userspace. Therefore it is
42  * highly recommended to use the provided helpers as much as possible.
43  *
44  * Because there is only one pointer per modeset object to hold a vfunc table
45  * for helper libraries they are by necessity shared among the different
46  * helpers.
47  *
48  * To make this clear all the helper vtables are pulled together in this location here.
49  */
50 
51 enum mode_set_atomic;
52 
53 /**
54  * struct drm_crtc_helper_funcs - helper operations for CRTCs
55  *
56  * These hooks are used by the legacy CRTC helpers, the transitional plane
57  * helpers and the new atomic modesetting helpers.
58  */
59 struct drm_crtc_helper_funcs {
60 	/**
61 	 * @dpms:
62 	 *
63 	 * Callback to control power levels on the CRTC.  If the mode passed in
64 	 * is unsupported, the provider must use the next lowest power level.
65 	 * This is used by the legacy CRTC helpers to implement DPMS
66 	 * functionality in drm_helper_connector_dpms().
67 	 *
68 	 * This callback is also used to disable a CRTC by calling it with
69 	 * DRM_MODE_DPMS_OFF if the @disable hook isn't used.
70 	 *
71 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
72 	 * also support using this hook for enabling and disabling a CRTC to
73 	 * facilitate transitions to atomic, but it is deprecated. Instead
74 	 * @atomic_enable and @atomic_disable should be used.
75 	 */
76 	void (*dpms)(struct drm_crtc *crtc, int mode);
77 
78 	/**
79 	 * @prepare:
80 	 *
81 	 * This callback should prepare the CRTC for a subsequent modeset, which
82 	 * in practice means the driver should disable the CRTC if it is
83 	 * running. Most drivers ended up implementing this by calling their
84 	 * @dpms hook with DRM_MODE_DPMS_OFF.
85 	 *
86 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
87 	 * also support using this hook for disabling a CRTC to facilitate
88 	 * transitions to atomic, but it is deprecated. Instead @atomic_disable
89 	 * should be used.
90 	 */
91 	void (*prepare)(struct drm_crtc *crtc);
92 
93 	/**
94 	 * @commit:
95 	 *
96 	 * This callback should commit the new mode on the CRTC after a modeset,
97 	 * which in practice means the driver should enable the CRTC.  Most
98 	 * drivers ended up implementing this by calling their @dpms hook with
99 	 * DRM_MODE_DPMS_ON.
100 	 *
101 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
102 	 * also support using this hook for enabling a CRTC to facilitate
103 	 * transitions to atomic, but it is deprecated. Instead @atomic_enable
104 	 * should be used.
105 	 */
106 	void (*commit)(struct drm_crtc *crtc);
107 
108 	/**
109 	 * @mode_valid:
110 	 *
111 	 * This callback is used to check if a specific mode is valid in this
112 	 * crtc. This should be implemented if the crtc has some sort of
113 	 * restriction in the modes it can display. For example, a given crtc
114 	 * may be responsible to set a clock value. If the clock can not
115 	 * produce all the values for the available modes then this callback
116 	 * can be used to restrict the number of modes to only the ones that
117 	 * can be displayed.
118 	 *
119 	 * This hook is used by the probe helpers to filter the mode list in
120 	 * drm_helper_probe_single_connector_modes(), and it is used by the
121 	 * atomic helpers to validate modes supplied by userspace in
122 	 * drm_atomic_helper_check_modeset().
123 	 *
124 	 * This function is optional.
125 	 *
126 	 * NOTE:
127 	 *
128 	 * Since this function is both called from the check phase of an atomic
129 	 * commit, and the mode validation in the probe paths it is not allowed
130 	 * to look at anything else but the passed-in mode, and validate it
131 	 * against configuration-invariant hardward constraints. Any further
132 	 * limits which depend upon the configuration can only be checked in
133 	 * @mode_fixup or @atomic_check.
134 	 *
135 	 * RETURNS:
136 	 *
137 	 * drm_mode_status Enum
138 	 */
139 	enum drm_mode_status (*mode_valid)(struct drm_crtc *crtc,
140 					   const struct drm_display_mode *mode);
141 
142 	/**
143 	 * @mode_fixup:
144 	 *
145 	 * This callback is used to validate a mode. The parameter mode is the
146 	 * display mode that userspace requested, adjusted_mode is the mode the
147 	 * encoders need to be fed with. Note that this is the inverse semantics
148 	 * of the meaning for the &drm_encoder and &drm_bridge_funcs.mode_fixup
149 	 * vfunc. If the CRTC cannot support the requested conversion from mode
150 	 * to adjusted_mode it should reject the modeset. See also
151 	 * &drm_crtc_state.adjusted_mode for more details.
152 	 *
153 	 * This function is used by both legacy CRTC helpers and atomic helpers.
154 	 * With atomic helpers it is optional.
155 	 *
156 	 * NOTE:
157 	 *
158 	 * This function is called in the check phase of atomic modesets, which
159 	 * can be aborted for any reason (including on userspace's request to
160 	 * just check whether a configuration would be possible). Atomic drivers
161 	 * MUST NOT touch any persistent state (hardware or software) or data
162 	 * structures except the passed in adjusted_mode parameter.
163 	 *
164 	 * This is in contrast to the legacy CRTC helpers where this was
165 	 * allowed.
166 	 *
167 	 * Atomic drivers which need to inspect and adjust more state should
168 	 * instead use the @atomic_check callback, but note that they're not
169 	 * perfectly equivalent: @mode_valid is called from
170 	 * drm_atomic_helper_check_modeset(), but @atomic_check is called from
171 	 * drm_atomic_helper_check_planes(), because originally it was meant for
172 	 * plane update checks only.
173 	 *
174 	 * Also beware that userspace can request its own custom modes, neither
175 	 * core nor helpers filter modes to the list of probe modes reported by
176 	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
177 	 * that modes are filtered consistently put any CRTC constraints and
178 	 * limits checks into @mode_valid.
179 	 *
180 	 * RETURNS:
181 	 *
182 	 * True if an acceptable configuration is possible, false if the modeset
183 	 * operation should be rejected.
184 	 */
185 	bool (*mode_fixup)(struct drm_crtc *crtc,
186 			   const struct drm_display_mode *mode,
187 			   struct drm_display_mode *adjusted_mode);
188 
189 	/**
190 	 * @mode_set:
191 	 *
192 	 * This callback is used by the legacy CRTC helpers to set a new mode,
193 	 * position and framebuffer. Since it ties the primary plane to every
194 	 * mode change it is incompatible with universal plane support. And
195 	 * since it can't update other planes it's incompatible with atomic
196 	 * modeset support.
197 	 *
198 	 * This callback is only used by CRTC helpers and deprecated.
199 	 *
200 	 * RETURNS:
201 	 *
202 	 * 0 on success or a negative error code on failure.
203 	 */
204 	int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode,
205 			struct drm_display_mode *adjusted_mode, int x, int y,
206 			struct drm_framebuffer *old_fb);
207 
208 	/**
209 	 * @mode_set_nofb:
210 	 *
211 	 * This callback is used to update the display mode of a CRTC without
212 	 * changing anything of the primary plane configuration. This fits the
213 	 * requirement of atomic and hence is used by the atomic helpers. It is
214 	 * also used by the transitional plane helpers to implement a
215 	 * @mode_set hook in drm_helper_crtc_mode_set().
216 	 *
217 	 * Note that the display pipe is completely off when this function is
218 	 * called. Atomic drivers which need hardware to be running before they
219 	 * program the new display mode (e.g. because they implement runtime PM)
220 	 * should not use this hook. This is because the helper library calls
221 	 * this hook only once per mode change and not every time the display
222 	 * pipeline is suspended using either DPMS or the new "ACTIVE" property.
223 	 * Which means register values set in this callback might get reset when
224 	 * the CRTC is suspended, but not restored.  Such drivers should instead
225 	 * move all their CRTC setup into the @atomic_enable callback.
226 	 *
227 	 * This callback is optional.
228 	 */
229 	void (*mode_set_nofb)(struct drm_crtc *crtc);
230 
231 	/**
232 	 * @mode_set_base:
233 	 *
234 	 * This callback is used by the legacy CRTC helpers to set a new
235 	 * framebuffer and scanout position. It is optional and used as an
236 	 * optimized fast-path instead of a full mode set operation with all the
237 	 * resulting flickering. If it is not present
238 	 * drm_crtc_helper_set_config() will fall back to a full modeset, using
239 	 * the @mode_set callback. Since it can't update other planes it's
240 	 * incompatible with atomic modeset support.
241 	 *
242 	 * This callback is only used by the CRTC helpers and deprecated.
243 	 *
244 	 * RETURNS:
245 	 *
246 	 * 0 on success or a negative error code on failure.
247 	 */
248 	int (*mode_set_base)(struct drm_crtc *crtc, int x, int y,
249 			     struct drm_framebuffer *old_fb);
250 
251 	/**
252 	 * @mode_set_base_atomic:
253 	 *
254 	 * This callback is used by the fbdev helpers to set a new framebuffer
255 	 * and scanout without sleeping, i.e. from an atomic calling context. It
256 	 * is only used to implement kgdb support.
257 	 *
258 	 * This callback is optional and only needed for kgdb support in the fbdev
259 	 * helpers.
260 	 *
261 	 * RETURNS:
262 	 *
263 	 * 0 on success or a negative error code on failure.
264 	 */
265 	int (*mode_set_base_atomic)(struct drm_crtc *crtc,
266 				    struct drm_framebuffer *fb, int x, int y,
267 				    enum mode_set_atomic);
268 
269 	/**
270 	 * @disable:
271 	 *
272 	 * This callback should be used to disable the CRTC. With the atomic
273 	 * drivers it is called after all encoders connected to this CRTC have
274 	 * been shut off already using their own
275 	 * &drm_encoder_helper_funcs.disable hook. If that sequence is too
276 	 * simple drivers can just add their own hooks and call it from this
277 	 * CRTC callback here by looping over all encoders connected to it using
278 	 * for_each_encoder_on_crtc().
279 	 *
280 	 * This hook is used both by legacy CRTC helpers and atomic helpers.
281 	 * Atomic drivers don't need to implement it if there's no need to
282 	 * disable anything at the CRTC level. To ensure that runtime PM
283 	 * handling (using either DPMS or the new "ACTIVE" property) works
284 	 * @disable must be the inverse of @atomic_enable for atomic drivers.
285 	 * Atomic drivers should consider to use @atomic_disable instead of
286 	 * this one.
287 	 *
288 	 * NOTE:
289 	 *
290 	 * With legacy CRTC helpers there's a big semantic difference between
291 	 * @disable and other hooks (like @prepare or @dpms) used to shut down a
292 	 * CRTC: @disable is only called when also logically disabling the
293 	 * display pipeline and needs to release any resources acquired in
294 	 * @mode_set (like shared PLLs, or again release pinned framebuffers).
295 	 *
296 	 * Therefore @disable must be the inverse of @mode_set plus @commit for
297 	 * drivers still using legacy CRTC helpers, which is different from the
298 	 * rules under atomic.
299 	 */
300 	void (*disable)(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() this hook is called
317 	 * after the &drm_plane_helper_funcs.atomic_check hook for planes, which
318 	 * allows drivers to assign shared resources requested by planes in this
319 	 * callback here. For more complicated dependencies the driver can call
320 	 * the provided check helpers multiple times until the computed state
321 	 * has a final 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 and 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 	 * Also beware that userspace can request its own custom modes, neither
341 	 * core nor helpers filter modes to the list of probe modes reported by
342 	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
343 	 * that modes are filtered consistently put any CRTC constraints and
344 	 * limits checks into @mode_valid.
345 	 *
346 	 * RETURNS:
347 	 *
348 	 * 0 on success, -EINVAL if the state or the transition can't be
349 	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
350 	 * attempt to obtain another state object ran into a &drm_modeset_lock
351 	 * deadlock.
352 	 */
353 	int (*atomic_check)(struct drm_crtc *crtc,
354 			    struct drm_crtc_state *state);
355 
356 	/**
357 	 * @atomic_begin:
358 	 *
359 	 * Drivers should prepare for an atomic update of multiple planes on
360 	 * a CRTC in this hook. Depending upon hardware this might be vblank
361 	 * evasion, blocking updates by setting bits or doing preparatory work
362 	 * for e.g. manual update display.
363 	 *
364 	 * This hook is called before any plane commit functions are called.
365 	 *
366 	 * Note that the power state of the display pipe when this function is
367 	 * called depends upon the exact helpers and calling sequence the driver
368 	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
369 	 * the tradeoffs and variants of plane commit helpers.
370 	 *
371 	 * This callback is used by the atomic modeset helpers and by the
372 	 * transitional plane helpers, but it is optional.
373 	 */
374 	void (*atomic_begin)(struct drm_crtc *crtc,
375 			     struct drm_crtc_state *old_crtc_state);
376 	/**
377 	 * @atomic_flush:
378 	 *
379 	 * Drivers should finalize an atomic update of multiple planes on
380 	 * a CRTC in this hook. Depending upon hardware this might include
381 	 * checking that vblank evasion was successful, unblocking updates by
382 	 * setting bits or setting the GO bit to flush out all updates.
383 	 *
384 	 * Simple hardware or hardware with special requirements can commit and
385 	 * flush out all updates for all planes from this hook and forgo all the
386 	 * other commit hooks for plane updates.
387 	 *
388 	 * This hook is called after any plane commit functions are called.
389 	 *
390 	 * Note that the power state of the display pipe when this function is
391 	 * called depends upon the exact helpers and calling sequence the driver
392 	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
393 	 * the tradeoffs and variants of plane commit helpers.
394 	 *
395 	 * This callback is used by the atomic modeset helpers and by the
396 	 * transitional plane helpers, but it is optional.
397 	 */
398 	void (*atomic_flush)(struct drm_crtc *crtc,
399 			     struct drm_crtc_state *old_crtc_state);
400 
401 	/**
402 	 * @atomic_enable:
403 	 *
404 	 * This callback should be used to enable the CRTC. With the atomic
405 	 * drivers it is called before all encoders connected to this CRTC are
406 	 * enabled through the encoder's own &drm_encoder_helper_funcs.enable
407 	 * hook.  If that sequence is too simple drivers can just add their own
408 	 * hooks and call it from this CRTC callback here by looping over all
409 	 * encoders connected to it using for_each_encoder_on_crtc().
410 	 *
411 	 * This hook is used only by atomic helpers, for symmetry with
412 	 * @atomic_disable. Atomic drivers don't need to implement it if there's
413 	 * no need to enable anything at the CRTC level. To ensure that runtime
414 	 * PM handling (using either DPMS or the new "ACTIVE" property) works
415 	 * @atomic_enable must be the inverse of @atomic_disable for atomic
416 	 * drivers.
417 	 *
418 	 * Drivers can use the @old_crtc_state input parameter if the operations
419 	 * needed to enable the CRTC don't depend solely on the new state but
420 	 * also on the transition between the old state and the new state.
421 	 */
422 	void (*atomic_enable)(struct drm_crtc *crtc,
423 			      struct drm_crtc_state *old_crtc_state);
424 
425 	/**
426 	 * @atomic_disable:
427 	 *
428 	 * This callback should be used to disable the CRTC. With the atomic
429 	 * drivers it is called after all encoders connected to this CRTC have
430 	 * been shut off already using their own
431 	 * &drm_encoder_helper_funcs.disable hook. If that sequence is too
432 	 * simple drivers can just add their own hooks and call it from this
433 	 * CRTC callback here by looping over all encoders connected to it using
434 	 * for_each_encoder_on_crtc().
435 	 *
436 	 * This hook is used only by atomic helpers. Atomic drivers don't
437 	 * need to implement it if there's no need to disable anything at the
438 	 * CRTC level.
439 	 *
440 	 * Comparing to @disable, this one provides the additional input
441 	 * parameter @old_crtc_state which could be used to access the old
442 	 * state. Atomic drivers should consider to use this one instead
443 	 * of @disable.
444 	 */
445 	void (*atomic_disable)(struct drm_crtc *crtc,
446 			       struct drm_crtc_state *old_crtc_state);
447 };
448 
449 /**
450  * drm_crtc_helper_add - sets the helper vtable for a crtc
451  * @crtc: DRM CRTC
452  * @funcs: helper vtable to set for @crtc
453  */
454 static inline void drm_crtc_helper_add(struct drm_crtc *crtc,
455 				       const struct drm_crtc_helper_funcs *funcs)
456 {
457 	crtc->helper_private = funcs;
458 }
459 
460 /**
461  * struct drm_encoder_helper_funcs - helper operations for encoders
462  *
463  * These hooks are used by the legacy CRTC helpers, the transitional plane
464  * helpers and the new atomic modesetting helpers.
465  */
466 struct drm_encoder_helper_funcs {
467 	/**
468 	 * @dpms:
469 	 *
470 	 * Callback to control power levels on the encoder.  If the mode passed in
471 	 * is unsupported, the provider must use the next lowest power level.
472 	 * This is used by the legacy encoder helpers to implement DPMS
473 	 * functionality in drm_helper_connector_dpms().
474 	 *
475 	 * This callback is also used to disable an encoder by calling it with
476 	 * DRM_MODE_DPMS_OFF if the @disable hook isn't used.
477 	 *
478 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
479 	 * also support using this hook for enabling and disabling an encoder to
480 	 * facilitate transitions to atomic, but it is deprecated. Instead
481 	 * @enable and @disable should be used.
482 	 */
483 	void (*dpms)(struct drm_encoder *encoder, int mode);
484 
485 	/**
486 	 * @mode_valid:
487 	 *
488 	 * This callback is used to check if a specific mode is valid in this
489 	 * encoder. This should be implemented if the encoder has some sort
490 	 * of restriction in the modes it can display. For example, a given
491 	 * encoder may be responsible to set a clock value. If the clock can
492 	 * not produce all the values for the available modes then this callback
493 	 * can be used to restrict the number of modes to only the ones that
494 	 * can be displayed.
495 	 *
496 	 * This hook is used by the probe helpers to filter the mode list in
497 	 * drm_helper_probe_single_connector_modes(), and it is used by the
498 	 * atomic helpers to validate modes supplied by userspace in
499 	 * drm_atomic_helper_check_modeset().
500 	 *
501 	 * This function is optional.
502 	 *
503 	 * NOTE:
504 	 *
505 	 * Since this function is both called from the check phase of an atomic
506 	 * commit, and the mode validation in the probe paths it is not allowed
507 	 * to look at anything else but the passed-in mode, and validate it
508 	 * against configuration-invariant hardward constraints. Any further
509 	 * limits which depend upon the configuration can only be checked in
510 	 * @mode_fixup or @atomic_check.
511 	 *
512 	 * RETURNS:
513 	 *
514 	 * drm_mode_status Enum
515 	 */
516 	enum drm_mode_status (*mode_valid)(struct drm_encoder *crtc,
517 					   const struct drm_display_mode *mode);
518 
519 	/**
520 	 * @mode_fixup:
521 	 *
522 	 * This callback is used to validate and adjust a mode. The parameter
523 	 * mode is the display mode that should be fed to the next element in
524 	 * the display chain, either the final &drm_connector or a &drm_bridge.
525 	 * The parameter adjusted_mode is the input mode the encoder requires. It
526 	 * can be modified by this callback and does not need to match mode. See
527 	 * also &drm_crtc_state.adjusted_mode for more details.
528 	 *
529 	 * This function is used by both legacy CRTC helpers and atomic helpers.
530 	 * This hook is optional.
531 	 *
532 	 * NOTE:
533 	 *
534 	 * This function is called in the check phase of atomic modesets, which
535 	 * can be aborted for any reason (including on userspace's request to
536 	 * just check whether a configuration would be possible). Atomic drivers
537 	 * MUST NOT touch any persistent state (hardware or software) or data
538 	 * structures except the passed in adjusted_mode parameter.
539 	 *
540 	 * This is in contrast to the legacy CRTC helpers where this was
541 	 * allowed.
542 	 *
543 	 * Atomic drivers which need to inspect and adjust more state should
544 	 * instead use the @atomic_check callback. If @atomic_check is used,
545 	 * this hook isn't called since @atomic_check allows a strict superset
546 	 * of the functionality of @mode_fixup.
547 	 *
548 	 * Also beware that userspace can request its own custom modes, neither
549 	 * core nor helpers filter modes to the list of probe modes reported by
550 	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
551 	 * that modes are filtered consistently put any encoder constraints and
552 	 * limits checks into @mode_valid.
553 	 *
554 	 * RETURNS:
555 	 *
556 	 * True if an acceptable configuration is possible, false if the modeset
557 	 * operation should be rejected.
558 	 */
559 	bool (*mode_fixup)(struct drm_encoder *encoder,
560 			   const struct drm_display_mode *mode,
561 			   struct drm_display_mode *adjusted_mode);
562 
563 	/**
564 	 * @prepare:
565 	 *
566 	 * This callback should prepare the encoder for a subsequent modeset,
567 	 * which in practice means the driver should disable the encoder if it
568 	 * is running. Most drivers ended up implementing this by calling their
569 	 * @dpms hook with DRM_MODE_DPMS_OFF.
570 	 *
571 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
572 	 * also support using this hook for disabling an encoder to facilitate
573 	 * transitions to atomic, but it is deprecated. Instead @disable should
574 	 * be used.
575 	 */
576 	void (*prepare)(struct drm_encoder *encoder);
577 
578 	/**
579 	 * @commit:
580 	 *
581 	 * This callback should commit the new mode on the encoder after a modeset,
582 	 * which in practice means the driver should enable the encoder.  Most
583 	 * drivers ended up implementing this by calling their @dpms hook with
584 	 * DRM_MODE_DPMS_ON.
585 	 *
586 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
587 	 * also support using this hook for enabling an encoder to facilitate
588 	 * transitions to atomic, but it is deprecated. Instead @enable should
589 	 * be used.
590 	 */
591 	void (*commit)(struct drm_encoder *encoder);
592 
593 	/**
594 	 * @mode_set:
595 	 *
596 	 * This callback is used to update the display mode of an encoder.
597 	 *
598 	 * Note that the display pipe is completely off when this function is
599 	 * called. Drivers which need hardware to be running before they program
600 	 * the new display mode (because they implement runtime PM) should not
601 	 * use this hook, because the helper library calls it only once and not
602 	 * every time the display pipeline is suspend using either DPMS or the
603 	 * new "ACTIVE" property. Such drivers should instead move all their
604 	 * encoder setup into the @enable callback.
605 	 *
606 	 * This callback is used both by the legacy CRTC helpers and the atomic
607 	 * modeset helpers. It is optional in the atomic helpers.
608 	 *
609 	 * NOTE:
610 	 *
611 	 * If the driver uses the atomic modeset helpers and needs to inspect
612 	 * the connector state or connector display info during mode setting,
613 	 * @atomic_mode_set can be used instead.
614 	 */
615 	void (*mode_set)(struct drm_encoder *encoder,
616 			 struct drm_display_mode *mode,
617 			 struct drm_display_mode *adjusted_mode);
618 
619 	/**
620 	 * @atomic_mode_set:
621 	 *
622 	 * This callback is used to update the display mode of an encoder.
623 	 *
624 	 * Note that the display pipe is completely off when this function is
625 	 * called. Drivers which need hardware to be running before they program
626 	 * the new display mode (because they implement runtime PM) should not
627 	 * use this hook, because the helper library calls it only once and not
628 	 * every time the display pipeline is suspended using either DPMS or the
629 	 * new "ACTIVE" property. Such drivers should instead move all their
630 	 * encoder setup into the @enable callback.
631 	 *
632 	 * This callback is used by the atomic modeset helpers in place of the
633 	 * @mode_set callback, if set by the driver. It is optional and should
634 	 * be used instead of @mode_set if the driver needs to inspect the
635 	 * connector state or display info, since there is no direct way to
636 	 * go from the encoder to the current connector.
637 	 */
638 	void (*atomic_mode_set)(struct drm_encoder *encoder,
639 				struct drm_crtc_state *crtc_state,
640 				struct drm_connector_state *conn_state);
641 
642 	/**
643 	 * @get_crtc:
644 	 *
645 	 * This callback is used by the legacy CRTC helpers to work around
646 	 * deficiencies in its own book-keeping.
647 	 *
648 	 * Do not use, use atomic helpers instead, which get the book keeping
649 	 * right.
650 	 *
651 	 * FIXME:
652 	 *
653 	 * Currently only nouveau is using this, and as soon as nouveau is
654 	 * atomic we can ditch this hook.
655 	 */
656 	struct drm_crtc *(*get_crtc)(struct drm_encoder *encoder);
657 
658 	/**
659 	 * @detect:
660 	 *
661 	 * This callback can be used by drivers who want to do detection on the
662 	 * encoder object instead of in connector functions.
663 	 *
664 	 * It is not used by any helper and therefore has purely driver-specific
665 	 * semantics. New drivers shouldn't use this and instead just implement
666 	 * their own private callbacks.
667 	 *
668 	 * FIXME:
669 	 *
670 	 * This should just be converted into a pile of driver vfuncs.
671 	 * Currently radeon, amdgpu and nouveau are using it.
672 	 */
673 	enum drm_connector_status (*detect)(struct drm_encoder *encoder,
674 					    struct drm_connector *connector);
675 
676 	/**
677 	 * @disable:
678 	 *
679 	 * This callback should be used to disable the encoder. With the atomic
680 	 * drivers it is called before this encoder's CRTC has been shut off
681 	 * using their own &drm_crtc_helper_funcs.disable hook.  If that
682 	 * sequence is too simple drivers can just add their own driver private
683 	 * encoder hooks and call them from CRTC's callback by looping over all
684 	 * encoders connected to it using for_each_encoder_on_crtc().
685 	 *
686 	 * This hook is used both by legacy CRTC helpers and atomic helpers.
687 	 * Atomic drivers don't need to implement it if there's no need to
688 	 * disable anything at the encoder level. To ensure that runtime PM
689 	 * handling (using either DPMS or the new "ACTIVE" property) works
690 	 * @disable must be the inverse of @enable for atomic drivers.
691 	 *
692 	 * NOTE:
693 	 *
694 	 * With legacy CRTC helpers there's a big semantic difference between
695 	 * @disable and other hooks (like @prepare or @dpms) used to shut down a
696 	 * encoder: @disable is only called when also logically disabling the
697 	 * display pipeline and needs to release any resources acquired in
698 	 * @mode_set (like shared PLLs, or again release pinned framebuffers).
699 	 *
700 	 * Therefore @disable must be the inverse of @mode_set plus @commit for
701 	 * drivers still using legacy CRTC helpers, which is different from the
702 	 * rules under atomic.
703 	 */
704 	void (*disable)(struct drm_encoder *encoder);
705 
706 	/**
707 	 * @enable:
708 	 *
709 	 * This callback should be used to enable the encoder. With the atomic
710 	 * drivers it is called after this encoder's CRTC has been enabled using
711 	 * their own &drm_crtc_helper_funcs.enable hook.  If that sequence is
712 	 * too simple drivers can just add their own driver private encoder
713 	 * hooks and call them from CRTC's callback by looping over all encoders
714 	 * connected to it using for_each_encoder_on_crtc().
715 	 *
716 	 * This hook is used only by atomic helpers, for symmetry with @disable.
717 	 * Atomic drivers don't need to implement it if there's no need to
718 	 * enable anything at the encoder level. To ensure that runtime PM handling
719 	 * (using either DPMS or the new "ACTIVE" property) works
720 	 * @enable must be the inverse of @disable for atomic drivers.
721 	 */
722 	void (*enable)(struct drm_encoder *encoder);
723 
724 	/**
725 	 * @atomic_check:
726 	 *
727 	 * This callback is used to validate encoder state for atomic drivers.
728 	 * Since the encoder is the object connecting the CRTC and connector it
729 	 * gets passed both states, to be able to validate interactions and
730 	 * update the CRTC to match what the encoder needs for the requested
731 	 * connector.
732 	 *
733 	 * Since this provides a strict superset of the functionality of
734 	 * @mode_fixup (the requested and adjusted modes are both available
735 	 * through the passed in &struct drm_crtc_state) @mode_fixup is not
736 	 * called when @atomic_check is implemented.
737 	 *
738 	 * This function is used by the atomic helpers, but it is optional.
739 	 *
740 	 * NOTE:
741 	 *
742 	 * This function is called in the check phase of an atomic update. The
743 	 * driver is not allowed to change anything outside of the free-standing
744 	 * state objects passed-in or assembled in the overall &drm_atomic_state
745 	 * update tracking structure.
746 	 *
747 	 * Also beware that userspace can request its own custom modes, neither
748 	 * core nor helpers filter modes to the list of probe modes reported by
749 	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
750 	 * that modes are filtered consistently put any encoder constraints and
751 	 * limits checks into @mode_valid.
752 	 *
753 	 * RETURNS:
754 	 *
755 	 * 0 on success, -EINVAL if the state or the transition can't be
756 	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
757 	 * attempt to obtain another state object ran into a &drm_modeset_lock
758 	 * deadlock.
759 	 */
760 	int (*atomic_check)(struct drm_encoder *encoder,
761 			    struct drm_crtc_state *crtc_state,
762 			    struct drm_connector_state *conn_state);
763 };
764 
765 /**
766  * drm_encoder_helper_add - sets the helper vtable for an encoder
767  * @encoder: DRM encoder
768  * @funcs: helper vtable to set for @encoder
769  */
770 static inline void drm_encoder_helper_add(struct drm_encoder *encoder,
771 					  const struct drm_encoder_helper_funcs *funcs)
772 {
773 	encoder->helper_private = funcs;
774 }
775 
776 /**
777  * struct drm_connector_helper_funcs - helper operations for connectors
778  *
779  * These functions are used by the atomic and legacy modeset helpers and by the
780  * probe helpers.
781  */
782 struct drm_connector_helper_funcs {
783 	/**
784 	 * @get_modes:
785 	 *
786 	 * This function should fill in all modes currently valid for the sink
787 	 * into the &drm_connector.probed_modes list. It should also update the
788 	 * EDID property by calling drm_connector_update_edid_property().
789 	 *
790 	 * The usual way to implement this is to cache the EDID retrieved in the
791 	 * probe callback somewhere in the driver-private connector structure.
792 	 * In this function drivers then parse the modes in the EDID and add
793 	 * them by calling drm_add_edid_modes(). But connectors that driver a
794 	 * fixed panel can also manually add specific modes using
795 	 * drm_mode_probed_add(). Drivers which manually add modes should also
796 	 * make sure that the &drm_connector.display_info,
797 	 * &drm_connector.width_mm and &drm_connector.height_mm fields are
798 	 * filled in.
799 	 *
800 	 * Virtual drivers that just want some standard VESA mode with a given
801 	 * resolution can call drm_add_modes_noedid(), and mark the preferred
802 	 * one using drm_set_preferred_mode().
803 	 *
804 	 * This function is only called after the @detect hook has indicated
805 	 * that a sink is connected and when the EDID isn't overridden through
806 	 * sysfs or the kernel commandline.
807 	 *
808 	 * This callback is used by the probe helpers in e.g.
809 	 * drm_helper_probe_single_connector_modes().
810 	 *
811 	 * To avoid races with concurrent connector state updates, the helper
812 	 * libraries always call this with the &drm_mode_config.connection_mutex
813 	 * held. Because of this it's safe to inspect &drm_connector->state.
814 	 *
815 	 * RETURNS:
816 	 *
817 	 * The number of modes added by calling drm_mode_probed_add().
818 	 */
819 	int (*get_modes)(struct drm_connector *connector);
820 
821 	/**
822 	 * @detect_ctx:
823 	 *
824 	 * Check to see if anything is attached to the connector. The parameter
825 	 * force is set to false whilst polling, true when checking the
826 	 * connector due to a user request. force can be used by the driver to
827 	 * avoid expensive, destructive operations during automated probing.
828 	 *
829 	 * This callback is optional, if not implemented the connector will be
830 	 * considered as always being attached.
831 	 *
832 	 * This is the atomic version of &drm_connector_funcs.detect.
833 	 *
834 	 * To avoid races against concurrent connector state updates, the
835 	 * helper libraries always call this with ctx set to a valid context,
836 	 * and &drm_mode_config.connection_mutex will always be locked with
837 	 * the ctx parameter set to this ctx. This allows taking additional
838 	 * locks as required.
839 	 *
840 	 * RETURNS:
841 	 *
842 	 * &drm_connector_status indicating the connector's status,
843 	 * or the error code returned by drm_modeset_lock(), -EDEADLK.
844 	 */
845 	int (*detect_ctx)(struct drm_connector *connector,
846 			  struct drm_modeset_acquire_ctx *ctx,
847 			  bool force);
848 
849 	/**
850 	 * @mode_valid:
851 	 *
852 	 * Callback to validate a mode for a connector, irrespective of the
853 	 * specific display configuration.
854 	 *
855 	 * This callback is used by the probe helpers to filter the mode list
856 	 * (which is usually derived from the EDID data block from the sink).
857 	 * See e.g. drm_helper_probe_single_connector_modes().
858 	 *
859 	 * This function is optional.
860 	 *
861 	 * NOTE:
862 	 *
863 	 * This only filters the mode list supplied to userspace in the
864 	 * GETCONNECTOR IOCTL. Compared to &drm_encoder_helper_funcs.mode_valid,
865 	 * &drm_crtc_helper_funcs.mode_valid and &drm_bridge_funcs.mode_valid,
866 	 * which are also called by the atomic helpers from
867 	 * drm_atomic_helper_check_modeset(). This allows userspace to force and
868 	 * ignore sink constraint (like the pixel clock limits in the screen's
869 	 * EDID), which is useful for e.g. testing, or working around a broken
870 	 * EDID. Any source hardware constraint (which always need to be
871 	 * enforced) therefore should be checked in one of the above callbacks,
872 	 * and not this one here.
873 	 *
874 	 * To avoid races with concurrent connector state updates, the helper
875 	 * libraries always call this with the &drm_mode_config.connection_mutex
876 	 * held. Because of this it's safe to inspect &drm_connector->state.
877          *
878 	 * RETURNS:
879 	 *
880 	 * Either &drm_mode_status.MODE_OK or one of the failure reasons in &enum
881 	 * drm_mode_status.
882 	 */
883 	enum drm_mode_status (*mode_valid)(struct drm_connector *connector,
884 					   struct drm_display_mode *mode);
885 	/**
886 	 * @best_encoder:
887 	 *
888 	 * This function should select the best encoder for the given connector.
889 	 *
890 	 * This function is used by both the atomic helpers (in the
891 	 * drm_atomic_helper_check_modeset() function) and in the legacy CRTC
892 	 * helpers.
893 	 *
894 	 * NOTE:
895 	 *
896 	 * In atomic drivers this function is called in the check phase of an
897 	 * atomic update. The driver is not allowed to change or inspect
898 	 * anything outside of arguments passed-in. Atomic drivers which need to
899 	 * inspect dynamic configuration state should instead use
900 	 * @atomic_best_encoder.
901 	 *
902 	 * You can leave this function to NULL if the connector is only
903 	 * attached to a single encoder and you are using the atomic helpers.
904 	 * In this case, the core will call drm_atomic_helper_best_encoder()
905 	 * for you.
906 	 *
907 	 * RETURNS:
908 	 *
909 	 * Encoder that should be used for the given connector and connector
910 	 * state, or NULL if no suitable encoder exists. Note that the helpers
911 	 * will ensure that encoders aren't used twice, drivers should not check
912 	 * for this.
913 	 */
914 	struct drm_encoder *(*best_encoder)(struct drm_connector *connector);
915 
916 	/**
917 	 * @atomic_best_encoder:
918 	 *
919 	 * This is the atomic version of @best_encoder for atomic drivers which
920 	 * need to select the best encoder depending upon the desired
921 	 * configuration and can't select it statically.
922 	 *
923 	 * This function is used by drm_atomic_helper_check_modeset().
924 	 * If it is not implemented, the core will fallback to @best_encoder
925 	 * (or drm_atomic_helper_best_encoder() if @best_encoder is NULL).
926 	 *
927 	 * NOTE:
928 	 *
929 	 * This function is called in the check phase of an atomic update. The
930 	 * driver is not allowed to change anything outside of the free-standing
931 	 * state objects passed-in or assembled in the overall &drm_atomic_state
932 	 * update tracking structure.
933 	 *
934 	 * RETURNS:
935 	 *
936 	 * Encoder that should be used for the given connector and connector
937 	 * state, or NULL if no suitable encoder exists. Note that the helpers
938 	 * will ensure that encoders aren't used twice, drivers should not check
939 	 * for this.
940 	 */
941 	struct drm_encoder *(*atomic_best_encoder)(struct drm_connector *connector,
942 						   struct drm_connector_state *connector_state);
943 
944 	/**
945 	 * @atomic_check:
946 	 *
947 	 * This hook is used to validate connector state. This function is
948 	 * called from &drm_atomic_helper_check_modeset, and is called when
949 	 * a connector property is set, or a modeset on the crtc is forced.
950 	 *
951 	 * Because &drm_atomic_helper_check_modeset may be called multiple times,
952 	 * this function should handle being called multiple times as well.
953 	 *
954 	 * This function is also allowed to inspect any other object's state and
955 	 * can add more state objects to the atomic commit if needed. Care must
956 	 * be taken though to ensure that state check and compute functions for
957 	 * these added states are all called, and derived state in other objects
958 	 * all updated. Again the recommendation is to just call check helpers
959 	 * until a maximal configuration is reached.
960 	 *
961 	 * NOTE:
962 	 *
963 	 * This function is called in the check phase of an atomic update. The
964 	 * driver is not allowed to change anything outside of the free-standing
965 	 * state objects passed-in or assembled in the overall &drm_atomic_state
966 	 * update tracking structure.
967 	 *
968 	 * RETURNS:
969 	 *
970 	 * 0 on success, -EINVAL if the state or the transition can't be
971 	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
972 	 * attempt to obtain another state object ran into a &drm_modeset_lock
973 	 * deadlock.
974 	 */
975 	int (*atomic_check)(struct drm_connector *connector,
976 			    struct drm_connector_state *state);
977 
978 	/**
979 	 * @atomic_commit:
980 	 *
981 	 * This hook is to be used by drivers implementing writeback connectors
982 	 * that need a point when to commit the writeback job to the hardware.
983 	 * The writeback_job to commit is available in
984 	 * &drm_connector_state.writeback_job.
985 	 *
986 	 * This hook is optional.
987 	 *
988 	 * This callback is used by the atomic modeset helpers.
989 	 */
990 	void (*atomic_commit)(struct drm_connector *connector,
991 			      struct drm_connector_state *state);
992 };
993 
994 /**
995  * drm_connector_helper_add - sets the helper vtable for a connector
996  * @connector: DRM connector
997  * @funcs: helper vtable to set for @connector
998  */
999 static inline void drm_connector_helper_add(struct drm_connector *connector,
1000 					    const struct drm_connector_helper_funcs *funcs)
1001 {
1002 	connector->helper_private = funcs;
1003 }
1004 
1005 /**
1006  * struct drm_plane_helper_funcs - helper operations for planes
1007  *
1008  * These functions are used by the atomic helpers and by the transitional plane
1009  * helpers.
1010  */
1011 struct drm_plane_helper_funcs {
1012 	/**
1013 	 * @prepare_fb:
1014 	 *
1015 	 * This hook is to prepare a framebuffer for scanout by e.g. pinning
1016 	 * its backing storage or relocating it into a contiguous block of
1017 	 * VRAM. Other possible preparatory work includes flushing caches.
1018 	 *
1019 	 * This function must not block for outstanding rendering, since it is
1020 	 * called in the context of the atomic IOCTL even for async commits to
1021 	 * be able to return any errors to userspace. Instead the recommended
1022 	 * way is to fill out the &drm_plane_state.fence of the passed-in
1023 	 * &drm_plane_state. If the driver doesn't support native fences then
1024 	 * equivalent functionality should be implemented through private
1025 	 * members in the plane structure.
1026 	 *
1027 	 * Drivers which always have their buffers pinned should use
1028 	 * drm_gem_fb_prepare_fb() for this hook.
1029 	 *
1030 	 * The helpers will call @cleanup_fb with matching arguments for every
1031 	 * successful call to this hook.
1032 	 *
1033 	 * This callback is used by the atomic modeset helpers and by the
1034 	 * transitional plane helpers, but it is optional.
1035 	 *
1036 	 * RETURNS:
1037 	 *
1038 	 * 0 on success or one of the following negative error codes allowed by
1039 	 * the &drm_mode_config_funcs.atomic_commit vfunc. When using helpers
1040 	 * this callback is the only one which can fail an atomic commit,
1041 	 * everything else must complete successfully.
1042 	 */
1043 	int (*prepare_fb)(struct drm_plane *plane,
1044 			  struct drm_plane_state *new_state);
1045 	/**
1046 	 * @cleanup_fb:
1047 	 *
1048 	 * This hook is called to clean up any resources allocated for the given
1049 	 * framebuffer and plane configuration in @prepare_fb.
1050 	 *
1051 	 * This callback is used by the atomic modeset helpers and by the
1052 	 * transitional plane helpers, but it is optional.
1053 	 */
1054 	void (*cleanup_fb)(struct drm_plane *plane,
1055 			   struct drm_plane_state *old_state);
1056 
1057 	/**
1058 	 * @atomic_check:
1059 	 *
1060 	 * Drivers should check plane specific constraints in this hook.
1061 	 *
1062 	 * When using drm_atomic_helper_check_planes() plane's @atomic_check
1063 	 * hooks are called before the ones for CRTCs, which allows drivers to
1064 	 * request shared resources that the CRTC controls here. For more
1065 	 * complicated dependencies the driver can call the provided check helpers
1066 	 * multiple times until the computed state has a final configuration and
1067 	 * everything has been checked.
1068 	 *
1069 	 * This function is also allowed to inspect any other object's state and
1070 	 * can add more state objects to the atomic commit if needed. Care must
1071 	 * be taken though to ensure that state check and compute functions for
1072 	 * these added states are all called, and derived state in other objects
1073 	 * all updated. Again the recommendation is to just call check helpers
1074 	 * until a maximal configuration is reached.
1075 	 *
1076 	 * This callback is used by the atomic modeset helpers and by the
1077 	 * transitional plane helpers, but it is optional.
1078 	 *
1079 	 * NOTE:
1080 	 *
1081 	 * This function is called in the check phase of an atomic update. The
1082 	 * driver is not allowed to change anything outside of the free-standing
1083 	 * state objects passed-in or assembled in the overall &drm_atomic_state
1084 	 * update tracking structure.
1085 	 *
1086 	 * RETURNS:
1087 	 *
1088 	 * 0 on success, -EINVAL if the state or the transition can't be
1089 	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
1090 	 * attempt to obtain another state object ran into a &drm_modeset_lock
1091 	 * deadlock.
1092 	 */
1093 	int (*atomic_check)(struct drm_plane *plane,
1094 			    struct drm_plane_state *state);
1095 
1096 	/**
1097 	 * @atomic_update:
1098 	 *
1099 	 * Drivers should use this function to update the plane state.  This
1100 	 * hook is called in-between the &drm_crtc_helper_funcs.atomic_begin and
1101 	 * drm_crtc_helper_funcs.atomic_flush callbacks.
1102 	 *
1103 	 * Note that the power state of the display pipe when this function is
1104 	 * called depends upon the exact helpers and calling sequence the driver
1105 	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
1106 	 * the tradeoffs and variants of plane commit helpers.
1107 	 *
1108 	 * This callback is used by the atomic modeset helpers and by the
1109 	 * transitional plane helpers, but it is optional.
1110 	 */
1111 	void (*atomic_update)(struct drm_plane *plane,
1112 			      struct drm_plane_state *old_state);
1113 	/**
1114 	 * @atomic_disable:
1115 	 *
1116 	 * Drivers should use this function to unconditionally disable a plane.
1117 	 * This hook is called in-between the
1118 	 * &drm_crtc_helper_funcs.atomic_begin and
1119 	 * drm_crtc_helper_funcs.atomic_flush callbacks. It is an alternative to
1120 	 * @atomic_update, which will be called for disabling planes, too, if
1121 	 * the @atomic_disable hook isn't implemented.
1122 	 *
1123 	 * This hook is also useful to disable planes in preparation of a modeset,
1124 	 * by calling drm_atomic_helper_disable_planes_on_crtc() from the
1125 	 * &drm_crtc_helper_funcs.disable hook.
1126 	 *
1127 	 * Note that the power state of the display pipe when this function is
1128 	 * called depends upon the exact helpers and calling sequence the driver
1129 	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
1130 	 * the tradeoffs and variants of plane commit helpers.
1131 	 *
1132 	 * This callback is used by the atomic modeset helpers and by the
1133 	 * transitional plane helpers, but it is optional.
1134 	 */
1135 	void (*atomic_disable)(struct drm_plane *plane,
1136 			       struct drm_plane_state *old_state);
1137 
1138 	/**
1139 	 * @atomic_async_check:
1140 	 *
1141 	 * Drivers should set this function pointer to check if the plane state
1142 	 * can be updated in a async fashion. Here async means "not vblank
1143 	 * synchronized".
1144 	 *
1145 	 * This hook is called by drm_atomic_async_check() to establish if a
1146 	 * given update can be committed asynchronously, that is, if it can
1147 	 * jump ahead of the state currently queued for update.
1148 	 *
1149 	 * RETURNS:
1150 	 *
1151 	 * Return 0 on success and any error returned indicates that the update
1152 	 * can not be applied in asynchronous manner.
1153 	 */
1154 	int (*atomic_async_check)(struct drm_plane *plane,
1155 				  struct drm_plane_state *state);
1156 
1157 	/**
1158 	 * @atomic_async_update:
1159 	 *
1160 	 * Drivers should set this function pointer to perform asynchronous
1161 	 * updates of planes, that is, jump ahead of the currently queued
1162 	 * state and update the plane. Here async means "not vblank
1163 	 * synchronized".
1164 	 *
1165 	 * This hook is called by drm_atomic_helper_async_commit().
1166 	 *
1167 	 * An async update will happen on legacy cursor updates. An async
1168 	 * update won't happen if there is an outstanding commit modifying
1169 	 * the same plane.
1170 	 *
1171 	 * Note that unlike &drm_plane_helper_funcs.atomic_update this hook
1172 	 * takes the new &drm_plane_state as parameter. When doing async_update
1173 	 * drivers shouldn't replace the &drm_plane_state but update the
1174 	 * current one with the new plane configurations in the new
1175 	 * plane_state.
1176 	 *
1177 	 * FIXME:
1178 	 *  - It only works for single plane updates
1179 	 *  - Async Pageflips are not supported yet
1180 	 *  - Some hw might still scan out the old buffer until the next
1181 	 *    vblank, however we let go of the fb references as soon as
1182 	 *    we run this hook. For now drivers must implement their own workers
1183 	 *    for deferring if needed, until a common solution is created.
1184 	 */
1185 	void (*atomic_async_update)(struct drm_plane *plane,
1186 				    struct drm_plane_state *new_state);
1187 };
1188 
1189 /**
1190  * drm_plane_helper_add - sets the helper vtable for a plane
1191  * @plane: DRM plane
1192  * @funcs: helper vtable to set for @plane
1193  */
1194 static inline void drm_plane_helper_add(struct drm_plane *plane,
1195 					const struct drm_plane_helper_funcs *funcs)
1196 {
1197 	plane->helper_private = funcs;
1198 }
1199 
1200 /**
1201  * struct drm_mode_config_helper_funcs - global modeset helper operations
1202  *
1203  * These helper functions are used by the atomic helpers.
1204  */
1205 struct drm_mode_config_helper_funcs {
1206 	/**
1207 	 * @atomic_commit_tail:
1208 	 *
1209 	 * This hook is used by the default atomic_commit() hook implemented in
1210 	 * drm_atomic_helper_commit() together with the nonblocking commit
1211 	 * helpers (see drm_atomic_helper_setup_commit() for a starting point)
1212 	 * to implement blocking and nonblocking commits easily. It is not used
1213 	 * by the atomic helpers
1214 	 *
1215 	 * This function is called when the new atomic state has already been
1216 	 * swapped into the various state pointers. The passed in state
1217 	 * therefore contains copies of the old/previous state. This hook should
1218 	 * commit the new state into hardware. Note that the helpers have
1219 	 * already waited for preceeding atomic commits and fences, but drivers
1220 	 * can add more waiting calls at the start of their implementation, e.g.
1221 	 * to wait for driver-internal request for implicit syncing, before
1222 	 * starting to commit the update to the hardware.
1223 	 *
1224 	 * After the atomic update is committed to the hardware this hook needs
1225 	 * to call drm_atomic_helper_commit_hw_done(). Then wait for the upate
1226 	 * to be executed by the hardware, for example using
1227 	 * drm_atomic_helper_wait_for_vblanks() or
1228 	 * drm_atomic_helper_wait_for_flip_done(), and then clean up the old
1229 	 * framebuffers using drm_atomic_helper_cleanup_planes().
1230 	 *
1231 	 * When disabling a CRTC this hook _must_ stall for the commit to
1232 	 * complete. Vblank waits don't work on disabled CRTC, hence the core
1233 	 * can't take care of this. And it also can't rely on the vblank event,
1234 	 * since that can be signalled already when the screen shows black,
1235 	 * which can happen much earlier than the last hardware access needed to
1236 	 * shut off the display pipeline completely.
1237 	 *
1238 	 * This hook is optional, the default implementation is
1239 	 * drm_atomic_helper_commit_tail().
1240 	 */
1241 	void (*atomic_commit_tail)(struct drm_atomic_state *state);
1242 };
1243 
1244 #endif
1245