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 struct drm_writeback_connector;
53 struct drm_writeback_job;
54 
55 /**
56  * struct drm_crtc_helper_funcs - helper operations for CRTCs
57  *
58  * These hooks are used by the legacy CRTC helpers, the transitional plane
59  * helpers and the new atomic modesetting helpers.
60  */
61 struct drm_crtc_helper_funcs {
62 	/**
63 	 * @dpms:
64 	 *
65 	 * Callback to control power levels on the CRTC.  If the mode passed in
66 	 * is unsupported, the provider must use the next lowest power level.
67 	 * This is used by the legacy CRTC helpers to implement DPMS
68 	 * functionality in drm_helper_connector_dpms().
69 	 *
70 	 * This callback is also used to disable a CRTC by calling it with
71 	 * DRM_MODE_DPMS_OFF if the @disable hook isn't used.
72 	 *
73 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
74 	 * also support using this hook for enabling and disabling a CRTC to
75 	 * facilitate transitions to atomic, but it is deprecated. Instead
76 	 * @atomic_enable and @atomic_disable should be used.
77 	 */
78 	void (*dpms)(struct drm_crtc *crtc, int mode);
79 
80 	/**
81 	 * @prepare:
82 	 *
83 	 * This callback should prepare the CRTC for a subsequent modeset, which
84 	 * in practice means the driver should disable the CRTC if it is
85 	 * running. Most drivers ended up implementing this by calling their
86 	 * @dpms hook with DRM_MODE_DPMS_OFF.
87 	 *
88 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
89 	 * also support using this hook for disabling a CRTC to facilitate
90 	 * transitions to atomic, but it is deprecated. Instead @atomic_disable
91 	 * should be used.
92 	 */
93 	void (*prepare)(struct drm_crtc *crtc);
94 
95 	/**
96 	 * @commit:
97 	 *
98 	 * This callback should commit the new mode on the CRTC after a modeset,
99 	 * which in practice means the driver should enable the CRTC.  Most
100 	 * drivers ended up implementing this by calling their @dpms hook with
101 	 * DRM_MODE_DPMS_ON.
102 	 *
103 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
104 	 * also support using this hook for enabling a CRTC to facilitate
105 	 * transitions to atomic, but it is deprecated. Instead @atomic_enable
106 	 * should be used.
107 	 */
108 	void (*commit)(struct drm_crtc *crtc);
109 
110 	/**
111 	 * @mode_valid:
112 	 *
113 	 * This callback is used to check if a specific mode is valid in this
114 	 * crtc. This should be implemented if the crtc has some sort of
115 	 * restriction in the modes it can display. For example, a given crtc
116 	 * may be responsible to set a clock value. If the clock can not
117 	 * produce all the values for the available modes then this callback
118 	 * can be used to restrict the number of modes to only the ones that
119 	 * can be displayed.
120 	 *
121 	 * This hook is used by the probe helpers to filter the mode list in
122 	 * drm_helper_probe_single_connector_modes(), and it is used by the
123 	 * atomic helpers to validate modes supplied by userspace in
124 	 * drm_atomic_helper_check_modeset().
125 	 *
126 	 * This function is optional.
127 	 *
128 	 * NOTE:
129 	 *
130 	 * Since this function is both called from the check phase of an atomic
131 	 * commit, and the mode validation in the probe paths it is not allowed
132 	 * to look at anything else but the passed-in mode, and validate it
133 	 * against configuration-invariant hardward constraints. Any further
134 	 * limits which depend upon the configuration can only be checked in
135 	 * @mode_fixup or @atomic_check.
136 	 *
137 	 * RETURNS:
138 	 *
139 	 * drm_mode_status Enum
140 	 */
141 	enum drm_mode_status (*mode_valid)(struct drm_crtc *crtc,
142 					   const struct drm_display_mode *mode);
143 
144 	/**
145 	 * @mode_fixup:
146 	 *
147 	 * This callback is used to validate a mode. The parameter mode is the
148 	 * display mode that userspace requested, adjusted_mode is the mode the
149 	 * encoders need to be fed with. Note that this is the inverse semantics
150 	 * of the meaning for the &drm_encoder and &drm_bridge_funcs.mode_fixup
151 	 * vfunc. If the CRTC cannot support the requested conversion from mode
152 	 * to adjusted_mode it should reject the modeset. See also
153 	 * &drm_crtc_state.adjusted_mode for more details.
154 	 *
155 	 * This function is used by both legacy CRTC helpers and atomic helpers.
156 	 * With atomic helpers it is optional.
157 	 *
158 	 * NOTE:
159 	 *
160 	 * This function is called in the check phase of atomic modesets, which
161 	 * can be aborted for any reason (including on userspace's request to
162 	 * just check whether a configuration would be possible). Atomic drivers
163 	 * MUST NOT touch any persistent state (hardware or software) or data
164 	 * structures except the passed in adjusted_mode parameter.
165 	 *
166 	 * This is in contrast to the legacy CRTC helpers where this was
167 	 * allowed.
168 	 *
169 	 * Atomic drivers which need to inspect and adjust more state should
170 	 * instead use the @atomic_check callback, but note that they're not
171 	 * perfectly equivalent: @mode_valid is called from
172 	 * drm_atomic_helper_check_modeset(), but @atomic_check is called from
173 	 * drm_atomic_helper_check_planes(), because originally it was meant for
174 	 * plane update checks only.
175 	 *
176 	 * Also beware that userspace can request its own custom modes, neither
177 	 * core nor helpers filter modes to the list of probe modes reported by
178 	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
179 	 * that modes are filtered consistently put any CRTC constraints and
180 	 * limits checks into @mode_valid.
181 	 *
182 	 * RETURNS:
183 	 *
184 	 * True if an acceptable configuration is possible, false if the modeset
185 	 * operation should be rejected.
186 	 */
187 	bool (*mode_fixup)(struct drm_crtc *crtc,
188 			   const struct drm_display_mode *mode,
189 			   struct drm_display_mode *adjusted_mode);
190 
191 	/**
192 	 * @mode_set:
193 	 *
194 	 * This callback is used by the legacy CRTC helpers to set a new mode,
195 	 * position and framebuffer. Since it ties the primary plane to every
196 	 * mode change it is incompatible with universal plane support. And
197 	 * since it can't update other planes it's incompatible with atomic
198 	 * modeset support.
199 	 *
200 	 * This callback is only used by CRTC helpers and deprecated.
201 	 *
202 	 * RETURNS:
203 	 *
204 	 * 0 on success or a negative error code on failure.
205 	 */
206 	int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode,
207 			struct drm_display_mode *adjusted_mode, int x, int y,
208 			struct drm_framebuffer *old_fb);
209 
210 	/**
211 	 * @mode_set_nofb:
212 	 *
213 	 * This callback is used to update the display mode of a CRTC without
214 	 * changing anything of the primary plane configuration. This fits the
215 	 * requirement of atomic and hence is used by the atomic helpers. It is
216 	 * also used by the transitional plane helpers to implement a
217 	 * @mode_set hook in drm_helper_crtc_mode_set().
218 	 *
219 	 * Note that the display pipe is completely off when this function is
220 	 * called. Atomic drivers which need hardware to be running before they
221 	 * program the new display mode (e.g. because they implement runtime PM)
222 	 * should not use this hook. This is because the helper library calls
223 	 * this hook only once per mode change and not every time the display
224 	 * pipeline is suspended using either DPMS or the new "ACTIVE" property.
225 	 * Which means register values set in this callback might get reset when
226 	 * the CRTC is suspended, but not restored.  Such drivers should instead
227 	 * move all their CRTC setup into the @atomic_enable callback.
228 	 *
229 	 * This callback is optional.
230 	 */
231 	void (*mode_set_nofb)(struct drm_crtc *crtc);
232 
233 	/**
234 	 * @mode_set_base:
235 	 *
236 	 * This callback is used by the legacy CRTC helpers to set a new
237 	 * framebuffer and scanout position. It is optional and used as an
238 	 * optimized fast-path instead of a full mode set operation with all the
239 	 * resulting flickering. If it is not present
240 	 * drm_crtc_helper_set_config() will fall back to a full modeset, using
241 	 * the @mode_set callback. Since it can't update other planes it's
242 	 * incompatible with atomic modeset support.
243 	 *
244 	 * This callback is only used by the CRTC helpers and deprecated.
245 	 *
246 	 * RETURNS:
247 	 *
248 	 * 0 on success or a negative error code on failure.
249 	 */
250 	int (*mode_set_base)(struct drm_crtc *crtc, int x, int y,
251 			     struct drm_framebuffer *old_fb);
252 
253 	/**
254 	 * @mode_set_base_atomic:
255 	 *
256 	 * This callback is used by the fbdev helpers to set a new framebuffer
257 	 * and scanout without sleeping, i.e. from an atomic calling context. It
258 	 * is only used to implement kgdb support.
259 	 *
260 	 * This callback is optional and only needed for kgdb support in the fbdev
261 	 * helpers.
262 	 *
263 	 * RETURNS:
264 	 *
265 	 * 0 on success or a negative error code on failure.
266 	 */
267 	int (*mode_set_base_atomic)(struct drm_crtc *crtc,
268 				    struct drm_framebuffer *fb, int x, int y,
269 				    enum mode_set_atomic);
270 
271 	/**
272 	 * @disable:
273 	 *
274 	 * This callback should be used to disable the CRTC. With the atomic
275 	 * drivers it is called after all encoders connected to this CRTC have
276 	 * been shut off already using their own
277 	 * &drm_encoder_helper_funcs.disable hook. If that sequence is too
278 	 * simple drivers can just add their own hooks and call it from this
279 	 * CRTC callback here by looping over all encoders connected to it using
280 	 * for_each_encoder_on_crtc().
281 	 *
282 	 * This hook is used both by legacy CRTC helpers and atomic helpers.
283 	 * Atomic drivers don't need to implement it if there's no need to
284 	 * disable anything at the CRTC level. To ensure that runtime PM
285 	 * handling (using either DPMS or the new "ACTIVE" property) works
286 	 * @disable must be the inverse of @atomic_enable for atomic drivers.
287 	 * Atomic drivers should consider to use @atomic_disable instead of
288 	 * this one.
289 	 *
290 	 * NOTE:
291 	 *
292 	 * With legacy CRTC helpers there's a big semantic difference between
293 	 * @disable and other hooks (like @prepare or @dpms) used to shut down a
294 	 * CRTC: @disable is only called when also logically disabling the
295 	 * display pipeline and needs to release any resources acquired in
296 	 * @mode_set (like shared PLLs, or again release pinned framebuffers).
297 	 *
298 	 * Therefore @disable must be the inverse of @mode_set plus @commit for
299 	 * drivers still using legacy CRTC helpers, which is different from the
300 	 * rules under atomic.
301 	 */
302 	void (*disable)(struct drm_crtc *crtc);
303 
304 	/**
305 	 * @atomic_check:
306 	 *
307 	 * Drivers should check plane-update related CRTC constraints in this
308 	 * hook. They can also check mode related limitations but need to be
309 	 * aware of the calling order, since this hook is used by
310 	 * drm_atomic_helper_check_planes() whereas the preparations needed to
311 	 * check output routing and the display mode is done in
312 	 * drm_atomic_helper_check_modeset(). Therefore drivers that want to
313 	 * check output routing and display mode constraints in this callback
314 	 * must ensure that drm_atomic_helper_check_modeset() has been called
315 	 * beforehand. This is calling order used by the default helper
316 	 * implementation in drm_atomic_helper_check().
317 	 *
318 	 * When using drm_atomic_helper_check_planes() this hook is called
319 	 * after the &drm_plane_helper_funcs.atomic_check hook for planes, which
320 	 * allows drivers to assign shared resources requested by planes in this
321 	 * callback here. For more complicated dependencies the driver can call
322 	 * the provided check helpers multiple times until the computed state
323 	 * has a final configuration and everything has been checked.
324 	 *
325 	 * This function is also allowed to inspect any other object's state and
326 	 * can add more state objects to the atomic commit if needed. Care must
327 	 * be taken though to ensure that state check and compute functions for
328 	 * these added states are all called, and derived state in other objects
329 	 * all updated. Again the recommendation is to just call check helpers
330 	 * until a maximal configuration is reached.
331 	 *
332 	 * This callback is used by the atomic modeset helpers and by the
333 	 * transitional plane helpers, but it is optional.
334 	 *
335 	 * NOTE:
336 	 *
337 	 * This function is called in the check phase of an atomic update. The
338 	 * driver is not allowed to change anything outside of the free-standing
339 	 * state object passed-in.
340 	 *
341 	 * Also beware that userspace can request its own custom modes, neither
342 	 * core nor helpers filter modes to the list of probe modes reported by
343 	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
344 	 * that modes are filtered consistently put any CRTC constraints and
345 	 * limits checks into @mode_valid.
346 	 *
347 	 * RETURNS:
348 	 *
349 	 * 0 on success, -EINVAL if the state or the transition can't be
350 	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
351 	 * attempt to obtain another state object ran into a &drm_modeset_lock
352 	 * deadlock.
353 	 */
354 	int (*atomic_check)(struct drm_crtc *crtc,
355 			    struct drm_atomic_state *state);
356 
357 	/**
358 	 * @atomic_begin:
359 	 *
360 	 * Drivers should prepare for an atomic update of multiple planes on
361 	 * a CRTC in this hook. Depending upon hardware this might be vblank
362 	 * evasion, blocking updates by setting bits or doing preparatory work
363 	 * for e.g. manual update display.
364 	 *
365 	 * This hook is called before any plane commit functions are called.
366 	 *
367 	 * Note that the power state of the display pipe when this function is
368 	 * called depends upon the exact helpers and calling sequence the driver
369 	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
370 	 * the tradeoffs and variants of plane commit helpers.
371 	 *
372 	 * This callback is used by the atomic modeset helpers and by the
373 	 * transitional plane helpers, but it is optional.
374 	 */
375 	void (*atomic_begin)(struct drm_crtc *crtc,
376 			     struct drm_atomic_state *state);
377 	/**
378 	 * @atomic_flush:
379 	 *
380 	 * Drivers should finalize an atomic update of multiple planes on
381 	 * a CRTC in this hook. Depending upon hardware this might include
382 	 * checking that vblank evasion was successful, unblocking updates by
383 	 * setting bits or setting the GO bit to flush out all updates.
384 	 *
385 	 * Simple hardware or hardware with special requirements can commit and
386 	 * flush out all updates for all planes from this hook and forgo all the
387 	 * other commit hooks for plane updates.
388 	 *
389 	 * This hook is called after any plane commit functions are called.
390 	 *
391 	 * Note that the power state of the display pipe when this function is
392 	 * called depends upon the exact helpers and calling sequence the driver
393 	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
394 	 * the tradeoffs and variants of plane commit helpers.
395 	 *
396 	 * This callback is used by the atomic modeset helpers and by the
397 	 * transitional plane helpers, but it is optional.
398 	 */
399 	void (*atomic_flush)(struct drm_crtc *crtc,
400 			     struct drm_atomic_state *state);
401 
402 	/**
403 	 * @atomic_enable:
404 	 *
405 	 * This callback should be used to enable the CRTC. With the atomic
406 	 * drivers it is called before all encoders connected to this CRTC are
407 	 * enabled through the encoder's own &drm_encoder_helper_funcs.enable
408 	 * hook.  If that sequence is too simple drivers can just add their own
409 	 * hooks and call it from this CRTC callback here by looping over all
410 	 * encoders connected to it using for_each_encoder_on_crtc().
411 	 *
412 	 * This hook is used only by atomic helpers, for symmetry with
413 	 * @atomic_disable. Atomic drivers don't need to implement it if there's
414 	 * no need to enable anything at the CRTC level. To ensure that runtime
415 	 * PM handling (using either DPMS or the new "ACTIVE" property) works
416 	 * @atomic_enable must be the inverse of @atomic_disable for atomic
417 	 * drivers.
418 	 *
419 	 * This function is optional.
420 	 */
421 	void (*atomic_enable)(struct drm_crtc *crtc,
422 			      struct drm_atomic_state *state);
423 
424 	/**
425 	 * @atomic_disable:
426 	 *
427 	 * This callback should be used to disable the CRTC. With the atomic
428 	 * drivers it is called after all encoders connected to this CRTC have
429 	 * been shut off already using their own
430 	 * &drm_encoder_helper_funcs.disable hook. If that sequence is too
431 	 * simple drivers can just add their own hooks and call it from this
432 	 * CRTC callback here by looping over all encoders connected to it using
433 	 * for_each_encoder_on_crtc().
434 	 *
435 	 * This hook is used only by atomic helpers. Atomic drivers don't
436 	 * need to implement it if there's no need to disable anything at the
437 	 * CRTC level.
438 	 *
439 	 * This function is optional.
440 	 */
441 	void (*atomic_disable)(struct drm_crtc *crtc,
442 			       struct drm_atomic_state *state);
443 
444 	/**
445 	 * @get_scanout_position:
446 	 *
447 	 * Called by vblank timestamping code.
448 	 *
449 	 * Returns the current display scanout position from a CRTC and an
450 	 * optional accurate ktime_get() timestamp of when the position was
451 	 * measured. Note that this is a helper callback which is only used
452 	 * if a driver uses drm_crtc_vblank_helper_get_vblank_timestamp()
453 	 * for the @drm_crtc_funcs.get_vblank_timestamp callback.
454 	 *
455 	 * Parameters:
456 	 *
457 	 * crtc:
458 	 *     The CRTC.
459 	 * in_vblank_irq:
460 	 *     True when called from drm_crtc_handle_vblank(). Some drivers
461 	 *     need to apply some workarounds for gpu-specific vblank irq
462 	 *     quirks if the flag is set.
463 	 * vpos:
464 	 *     Target location for current vertical scanout position.
465 	 * hpos:
466 	 *     Target location for current horizontal scanout position.
467 	 * stime:
468 	 *     Target location for timestamp taken immediately before
469 	 *     scanout position query. Can be NULL to skip timestamp.
470 	 * etime:
471 	 *     Target location for timestamp taken immediately after
472 	 *     scanout position query. Can be NULL to skip timestamp.
473 	 * mode:
474 	 *     Current display timings.
475 	 *
476 	 * Returns vpos as a positive number while in active scanout area.
477 	 * Returns vpos as a negative number inside vblank, counting the number
478 	 * of scanlines to go until end of vblank, e.g., -1 means "one scanline
479 	 * until start of active scanout / end of vblank."
480 	 *
481 	 * Returns:
482 	 *
483 	 * True on success, false if a reliable scanout position counter could
484 	 * not be read out.
485 	 */
486 	bool (*get_scanout_position)(struct drm_crtc *crtc,
487 				     bool in_vblank_irq, int *vpos, int *hpos,
488 				     ktime_t *stime, ktime_t *etime,
489 				     const struct drm_display_mode *mode);
490 };
491 
492 /**
493  * drm_crtc_helper_add - sets the helper vtable for a crtc
494  * @crtc: DRM CRTC
495  * @funcs: helper vtable to set for @crtc
496  */
497 static inline void drm_crtc_helper_add(struct drm_crtc *crtc,
498 				       const struct drm_crtc_helper_funcs *funcs)
499 {
500 	crtc->helper_private = funcs;
501 }
502 
503 /**
504  * struct drm_encoder_helper_funcs - helper operations for encoders
505  *
506  * These hooks are used by the legacy CRTC helpers, the transitional plane
507  * helpers and the new atomic modesetting helpers.
508  */
509 struct drm_encoder_helper_funcs {
510 	/**
511 	 * @dpms:
512 	 *
513 	 * Callback to control power levels on the encoder.  If the mode passed in
514 	 * is unsupported, the provider must use the next lowest power level.
515 	 * This is used by the legacy encoder helpers to implement DPMS
516 	 * functionality in drm_helper_connector_dpms().
517 	 *
518 	 * This callback is also used to disable an encoder by calling it with
519 	 * DRM_MODE_DPMS_OFF if the @disable hook isn't used.
520 	 *
521 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
522 	 * also support using this hook for enabling and disabling an encoder to
523 	 * facilitate transitions to atomic, but it is deprecated. Instead
524 	 * @enable and @disable should be used.
525 	 */
526 	void (*dpms)(struct drm_encoder *encoder, int mode);
527 
528 	/**
529 	 * @mode_valid:
530 	 *
531 	 * This callback is used to check if a specific mode is valid in this
532 	 * encoder. This should be implemented if the encoder has some sort
533 	 * of restriction in the modes it can display. For example, a given
534 	 * encoder may be responsible to set a clock value. If the clock can
535 	 * not produce all the values for the available modes then this callback
536 	 * can be used to restrict the number of modes to only the ones that
537 	 * can be displayed.
538 	 *
539 	 * This hook is used by the probe helpers to filter the mode list in
540 	 * drm_helper_probe_single_connector_modes(), and it is used by the
541 	 * atomic helpers to validate modes supplied by userspace in
542 	 * drm_atomic_helper_check_modeset().
543 	 *
544 	 * This function is optional.
545 	 *
546 	 * NOTE:
547 	 *
548 	 * Since this function is both called from the check phase of an atomic
549 	 * commit, and the mode validation in the probe paths it is not allowed
550 	 * to look at anything else but the passed-in mode, and validate it
551 	 * against configuration-invariant hardward constraints. Any further
552 	 * limits which depend upon the configuration can only be checked in
553 	 * @mode_fixup or @atomic_check.
554 	 *
555 	 * RETURNS:
556 	 *
557 	 * drm_mode_status Enum
558 	 */
559 	enum drm_mode_status (*mode_valid)(struct drm_encoder *crtc,
560 					   const struct drm_display_mode *mode);
561 
562 	/**
563 	 * @mode_fixup:
564 	 *
565 	 * This callback is used to validate and adjust a mode. The parameter
566 	 * mode is the display mode that should be fed to the next element in
567 	 * the display chain, either the final &drm_connector or a &drm_bridge.
568 	 * The parameter adjusted_mode is the input mode the encoder requires. It
569 	 * can be modified by this callback and does not need to match mode. See
570 	 * also &drm_crtc_state.adjusted_mode for more details.
571 	 *
572 	 * This function is used by both legacy CRTC helpers and atomic helpers.
573 	 * This hook is optional.
574 	 *
575 	 * NOTE:
576 	 *
577 	 * This function is called in the check phase of atomic modesets, which
578 	 * can be aborted for any reason (including on userspace's request to
579 	 * just check whether a configuration would be possible). Atomic drivers
580 	 * MUST NOT touch any persistent state (hardware or software) or data
581 	 * structures except the passed in adjusted_mode parameter.
582 	 *
583 	 * This is in contrast to the legacy CRTC helpers where this was
584 	 * allowed.
585 	 *
586 	 * Atomic drivers which need to inspect and adjust more state should
587 	 * instead use the @atomic_check callback. If @atomic_check is used,
588 	 * this hook isn't called since @atomic_check allows a strict superset
589 	 * of the functionality of @mode_fixup.
590 	 *
591 	 * Also beware that userspace can request its own custom modes, neither
592 	 * core nor helpers filter modes to the list of probe modes reported by
593 	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
594 	 * that modes are filtered consistently put any encoder constraints and
595 	 * limits checks into @mode_valid.
596 	 *
597 	 * RETURNS:
598 	 *
599 	 * True if an acceptable configuration is possible, false if the modeset
600 	 * operation should be rejected.
601 	 */
602 	bool (*mode_fixup)(struct drm_encoder *encoder,
603 			   const struct drm_display_mode *mode,
604 			   struct drm_display_mode *adjusted_mode);
605 
606 	/**
607 	 * @prepare:
608 	 *
609 	 * This callback should prepare the encoder for a subsequent modeset,
610 	 * which in practice means the driver should disable the encoder if it
611 	 * is running. Most drivers ended up implementing this by calling their
612 	 * @dpms hook with DRM_MODE_DPMS_OFF.
613 	 *
614 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
615 	 * also support using this hook for disabling an encoder to facilitate
616 	 * transitions to atomic, but it is deprecated. Instead @disable should
617 	 * be used.
618 	 */
619 	void (*prepare)(struct drm_encoder *encoder);
620 
621 	/**
622 	 * @commit:
623 	 *
624 	 * This callback should commit the new mode on the encoder after a modeset,
625 	 * which in practice means the driver should enable the encoder.  Most
626 	 * drivers ended up implementing this by calling their @dpms hook with
627 	 * DRM_MODE_DPMS_ON.
628 	 *
629 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
630 	 * also support using this hook for enabling an encoder to facilitate
631 	 * transitions to atomic, but it is deprecated. Instead @enable should
632 	 * be used.
633 	 */
634 	void (*commit)(struct drm_encoder *encoder);
635 
636 	/**
637 	 * @mode_set:
638 	 *
639 	 * This callback is used to update the display mode of an encoder.
640 	 *
641 	 * Note that the display pipe is completely off when this function is
642 	 * called. Drivers which need hardware to be running before they program
643 	 * the new display mode (because they implement runtime PM) should not
644 	 * use this hook, because the helper library calls it only once and not
645 	 * every time the display pipeline is suspend using either DPMS or the
646 	 * new "ACTIVE" property. Such drivers should instead move all their
647 	 * encoder setup into the @enable callback.
648 	 *
649 	 * This callback is used both by the legacy CRTC helpers and the atomic
650 	 * modeset helpers. It is optional in the atomic helpers.
651 	 *
652 	 * NOTE:
653 	 *
654 	 * If the driver uses the atomic modeset helpers and needs to inspect
655 	 * the connector state or connector display info during mode setting,
656 	 * @atomic_mode_set can be used instead.
657 	 */
658 	void (*mode_set)(struct drm_encoder *encoder,
659 			 struct drm_display_mode *mode,
660 			 struct drm_display_mode *adjusted_mode);
661 
662 	/**
663 	 * @atomic_mode_set:
664 	 *
665 	 * This callback is used to update the display mode of an encoder.
666 	 *
667 	 * Note that the display pipe is completely off when this function is
668 	 * called. Drivers which need hardware to be running before they program
669 	 * the new display mode (because they implement runtime PM) should not
670 	 * use this hook, because the helper library calls it only once and not
671 	 * every time the display pipeline is suspended using either DPMS or the
672 	 * new "ACTIVE" property. Such drivers should instead move all their
673 	 * encoder setup into the @enable callback.
674 	 *
675 	 * This callback is used by the atomic modeset helpers in place of the
676 	 * @mode_set callback, if set by the driver. It is optional and should
677 	 * be used instead of @mode_set if the driver needs to inspect the
678 	 * connector state or display info, since there is no direct way to
679 	 * go from the encoder to the current connector.
680 	 */
681 	void (*atomic_mode_set)(struct drm_encoder *encoder,
682 				struct drm_crtc_state *crtc_state,
683 				struct drm_connector_state *conn_state);
684 
685 	/**
686 	 * @detect:
687 	 *
688 	 * This callback can be used by drivers who want to do detection on the
689 	 * encoder object instead of in connector functions.
690 	 *
691 	 * It is not used by any helper and therefore has purely driver-specific
692 	 * semantics. New drivers shouldn't use this and instead just implement
693 	 * their own private callbacks.
694 	 *
695 	 * FIXME:
696 	 *
697 	 * This should just be converted into a pile of driver vfuncs.
698 	 * Currently radeon, amdgpu and nouveau are using it.
699 	 */
700 	enum drm_connector_status (*detect)(struct drm_encoder *encoder,
701 					    struct drm_connector *connector);
702 
703 	/**
704 	 * @atomic_disable:
705 	 *
706 	 * This callback should be used to disable the encoder. With the atomic
707 	 * drivers it is called before this encoder's CRTC has been shut off
708 	 * using their own &drm_crtc_helper_funcs.atomic_disable hook. If that
709 	 * sequence is too simple drivers can just add their own driver private
710 	 * encoder hooks and call them from CRTC's callback by looping over all
711 	 * encoders connected to it using for_each_encoder_on_crtc().
712 	 *
713 	 * This callback is a variant of @disable that provides the atomic state
714 	 * to the driver. If @atomic_disable is implemented, @disable is not
715 	 * called by the helpers.
716 	 *
717 	 * This hook is only used by atomic helpers. Atomic drivers don't need
718 	 * to implement it if there's no need to disable anything at the encoder
719 	 * level. To ensure that runtime PM handling (using either DPMS or the
720 	 * new "ACTIVE" property) works @atomic_disable must be the inverse of
721 	 * @atomic_enable.
722 	 */
723 	void (*atomic_disable)(struct drm_encoder *encoder,
724 			       struct drm_atomic_state *state);
725 
726 	/**
727 	 * @atomic_enable:
728 	 *
729 	 * This callback should be used to enable the encoder. It is called
730 	 * after this encoder's CRTC has been enabled using their own
731 	 * &drm_crtc_helper_funcs.atomic_enable hook. If that sequence is
732 	 * too simple drivers can just add their own driver private encoder
733 	 * hooks and call them from CRTC's callback by looping over all encoders
734 	 * connected to it using for_each_encoder_on_crtc().
735 	 *
736 	 * This callback is a variant of @enable that provides the atomic state
737 	 * to the driver. If @atomic_enable is implemented, @enable is not
738 	 * called by the helpers.
739 	 *
740 	 * This hook is only used by atomic helpers, it is the opposite of
741 	 * @atomic_disable. Atomic drivers don't need to implement it if there's
742 	 * no need to enable anything at the encoder level. To ensure that
743 	 * runtime PM handling works @atomic_enable must be the inverse of
744 	 * @atomic_disable.
745 	 */
746 	void (*atomic_enable)(struct drm_encoder *encoder,
747 			      struct drm_atomic_state *state);
748 
749 	/**
750 	 * @disable:
751 	 *
752 	 * This callback should be used to disable the encoder. With the atomic
753 	 * drivers it is called before this encoder's CRTC has been shut off
754 	 * using their own &drm_crtc_helper_funcs.disable hook.  If that
755 	 * sequence is too simple drivers can just add their own driver private
756 	 * encoder hooks and call them from CRTC's callback by looping over all
757 	 * encoders connected to it using for_each_encoder_on_crtc().
758 	 *
759 	 * This hook is used both by legacy CRTC helpers and atomic helpers.
760 	 * Atomic drivers don't need to implement it if there's no need to
761 	 * disable anything at the encoder level. To ensure that runtime PM
762 	 * handling (using either DPMS or the new "ACTIVE" property) works
763 	 * @disable must be the inverse of @enable for atomic drivers.
764 	 *
765 	 * For atomic drivers also consider @atomic_disable and save yourself
766 	 * from having to read the NOTE below!
767 	 *
768 	 * NOTE:
769 	 *
770 	 * With legacy CRTC helpers there's a big semantic difference between
771 	 * @disable and other hooks (like @prepare or @dpms) used to shut down a
772 	 * encoder: @disable is only called when also logically disabling the
773 	 * display pipeline and needs to release any resources acquired in
774 	 * @mode_set (like shared PLLs, or again release pinned framebuffers).
775 	 *
776 	 * Therefore @disable must be the inverse of @mode_set plus @commit for
777 	 * drivers still using legacy CRTC helpers, which is different from the
778 	 * rules under atomic.
779 	 */
780 	void (*disable)(struct drm_encoder *encoder);
781 
782 	/**
783 	 * @enable:
784 	 *
785 	 * This callback should be used to enable the encoder. With the atomic
786 	 * drivers it is called after this encoder's CRTC has been enabled using
787 	 * their own &drm_crtc_helper_funcs.enable hook.  If that sequence is
788 	 * too simple drivers can just add their own driver private encoder
789 	 * hooks and call them from CRTC's callback by looping over all encoders
790 	 * connected to it using for_each_encoder_on_crtc().
791 	 *
792 	 * This hook is only used by atomic helpers, it is the opposite of
793 	 * @disable. Atomic drivers don't need to implement it if there's no
794 	 * need to enable anything at the encoder level. To ensure that
795 	 * runtime PM handling (using either DPMS or the new "ACTIVE" property)
796 	 * works @enable must be the inverse of @disable for atomic drivers.
797 	 */
798 	void (*enable)(struct drm_encoder *encoder);
799 
800 	/**
801 	 * @atomic_check:
802 	 *
803 	 * This callback is used to validate encoder state for atomic drivers.
804 	 * Since the encoder is the object connecting the CRTC and connector it
805 	 * gets passed both states, to be able to validate interactions and
806 	 * update the CRTC to match what the encoder needs for the requested
807 	 * connector.
808 	 *
809 	 * Since this provides a strict superset of the functionality of
810 	 * @mode_fixup (the requested and adjusted modes are both available
811 	 * through the passed in &struct drm_crtc_state) @mode_fixup is not
812 	 * called when @atomic_check is implemented.
813 	 *
814 	 * This function is used by the atomic helpers, but it is optional.
815 	 *
816 	 * NOTE:
817 	 *
818 	 * This function is called in the check phase of an atomic update. The
819 	 * driver is not allowed to change anything outside of the free-standing
820 	 * state objects passed-in or assembled in the overall &drm_atomic_state
821 	 * update tracking structure.
822 	 *
823 	 * Also beware that userspace can request its own custom modes, neither
824 	 * core nor helpers filter modes to the list of probe modes reported by
825 	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
826 	 * that modes are filtered consistently put any encoder constraints and
827 	 * limits checks into @mode_valid.
828 	 *
829 	 * RETURNS:
830 	 *
831 	 * 0 on success, -EINVAL if the state or the transition can't be
832 	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
833 	 * attempt to obtain another state object ran into a &drm_modeset_lock
834 	 * deadlock.
835 	 */
836 	int (*atomic_check)(struct drm_encoder *encoder,
837 			    struct drm_crtc_state *crtc_state,
838 			    struct drm_connector_state *conn_state);
839 };
840 
841 /**
842  * drm_encoder_helper_add - sets the helper vtable for an encoder
843  * @encoder: DRM encoder
844  * @funcs: helper vtable to set for @encoder
845  */
846 static inline void drm_encoder_helper_add(struct drm_encoder *encoder,
847 					  const struct drm_encoder_helper_funcs *funcs)
848 {
849 	encoder->helper_private = funcs;
850 }
851 
852 /**
853  * struct drm_connector_helper_funcs - helper operations for connectors
854  *
855  * These functions are used by the atomic and legacy modeset helpers and by the
856  * probe helpers.
857  */
858 struct drm_connector_helper_funcs {
859 	/**
860 	 * @get_modes:
861 	 *
862 	 * This function should fill in all modes currently valid for the sink
863 	 * into the &drm_connector.probed_modes list. It should also update the
864 	 * EDID property by calling drm_connector_update_edid_property().
865 	 *
866 	 * The usual way to implement this is to cache the EDID retrieved in the
867 	 * probe callback somewhere in the driver-private connector structure.
868 	 * In this function drivers then parse the modes in the EDID and add
869 	 * them by calling drm_add_edid_modes(). But connectors that drive a
870 	 * fixed panel can also manually add specific modes using
871 	 * drm_mode_probed_add(). Drivers which manually add modes should also
872 	 * make sure that the &drm_connector.display_info,
873 	 * &drm_connector.width_mm and &drm_connector.height_mm fields are
874 	 * filled in.
875 	 *
876 	 * Note that the caller function will automatically add standard VESA
877 	 * DMT modes up to 1024x768 if the .get_modes() helper operation returns
878 	 * no mode and if the connector status is connector_status_connected or
879 	 * connector_status_unknown. There is no need to call
880 	 * drm_add_modes_noedid() manually in that case.
881 	 *
882 	 * Virtual drivers that just want some standard VESA mode with a given
883 	 * resolution can call drm_add_modes_noedid(), and mark the preferred
884 	 * one using drm_set_preferred_mode().
885 	 *
886 	 * This function is only called after the @detect hook has indicated
887 	 * that a sink is connected and when the EDID isn't overridden through
888 	 * sysfs or the kernel commandline.
889 	 *
890 	 * This callback is used by the probe helpers in e.g.
891 	 * drm_helper_probe_single_connector_modes().
892 	 *
893 	 * To avoid races with concurrent connector state updates, the helper
894 	 * libraries always call this with the &drm_mode_config.connection_mutex
895 	 * held. Because of this it's safe to inspect &drm_connector->state.
896 	 *
897 	 * RETURNS:
898 	 *
899 	 * The number of modes added by calling drm_mode_probed_add().
900 	 */
901 	int (*get_modes)(struct drm_connector *connector);
902 
903 	/**
904 	 * @detect_ctx:
905 	 *
906 	 * Check to see if anything is attached to the connector. The parameter
907 	 * force is set to false whilst polling, true when checking the
908 	 * connector due to a user request. force can be used by the driver to
909 	 * avoid expensive, destructive operations during automated probing.
910 	 *
911 	 * This callback is optional, if not implemented the connector will be
912 	 * considered as always being attached.
913 	 *
914 	 * This is the atomic version of &drm_connector_funcs.detect.
915 	 *
916 	 * To avoid races against concurrent connector state updates, the
917 	 * helper libraries always call this with ctx set to a valid context,
918 	 * and &drm_mode_config.connection_mutex will always be locked with
919 	 * the ctx parameter set to this ctx. This allows taking additional
920 	 * locks as required.
921 	 *
922 	 * RETURNS:
923 	 *
924 	 * &drm_connector_status indicating the connector's status,
925 	 * or the error code returned by drm_modeset_lock(), -EDEADLK.
926 	 */
927 	int (*detect_ctx)(struct drm_connector *connector,
928 			  struct drm_modeset_acquire_ctx *ctx,
929 			  bool force);
930 
931 	/**
932 	 * @mode_valid:
933 	 *
934 	 * Callback to validate a mode for a connector, irrespective of the
935 	 * specific display configuration.
936 	 *
937 	 * This callback is used by the probe helpers to filter the mode list
938 	 * (which is usually derived from the EDID data block from the sink).
939 	 * See e.g. drm_helper_probe_single_connector_modes().
940 	 *
941 	 * This function is optional.
942 	 *
943 	 * NOTE:
944 	 *
945 	 * This only filters the mode list supplied to userspace in the
946 	 * GETCONNECTOR IOCTL. Compared to &drm_encoder_helper_funcs.mode_valid,
947 	 * &drm_crtc_helper_funcs.mode_valid and &drm_bridge_funcs.mode_valid,
948 	 * which are also called by the atomic helpers from
949 	 * drm_atomic_helper_check_modeset(). This allows userspace to force and
950 	 * ignore sink constraint (like the pixel clock limits in the screen's
951 	 * EDID), which is useful for e.g. testing, or working around a broken
952 	 * EDID. Any source hardware constraint (which always need to be
953 	 * enforced) therefore should be checked in one of the above callbacks,
954 	 * and not this one here.
955 	 *
956 	 * To avoid races with concurrent connector state updates, the helper
957 	 * libraries always call this with the &drm_mode_config.connection_mutex
958 	 * held. Because of this it's safe to inspect &drm_connector->state.
959          *
960 	 * RETURNS:
961 	 *
962 	 * Either &drm_mode_status.MODE_OK or one of the failure reasons in &enum
963 	 * drm_mode_status.
964 	 */
965 	enum drm_mode_status (*mode_valid)(struct drm_connector *connector,
966 					   struct drm_display_mode *mode);
967 
968 	/**
969 	 * @mode_valid_ctx:
970 	 *
971 	 * Callback to validate a mode for a connector, irrespective of the
972 	 * specific display configuration.
973 	 *
974 	 * This callback is used by the probe helpers to filter the mode list
975 	 * (which is usually derived from the EDID data block from the sink).
976 	 * See e.g. drm_helper_probe_single_connector_modes().
977 	 *
978 	 * This function is optional, and is the atomic version of
979 	 * &drm_connector_helper_funcs.mode_valid.
980 	 *
981 	 * To allow for accessing the atomic state of modesetting objects, the
982 	 * helper libraries always call this with ctx set to a valid context,
983 	 * and &drm_mode_config.connection_mutex will always be locked with
984 	 * the ctx parameter set to @ctx. This allows for taking additional
985 	 * locks as required.
986 	 *
987 	 * Even though additional locks may be acquired, this callback is
988 	 * still expected not to take any constraints into account which would
989 	 * be influenced by the currently set display state - such constraints
990 	 * should be handled in the driver's atomic check. For example, if a
991 	 * connector shares display bandwidth with other connectors then it
992 	 * would be ok to validate the minimum bandwidth requirement of a mode
993 	 * against the maximum possible bandwidth of the connector. But it
994 	 * wouldn't be ok to take the current bandwidth usage of other
995 	 * connectors into account, as this would change depending on the
996 	 * display state.
997 	 *
998 	 * Returns:
999 	 * 0 if &drm_connector_helper_funcs.mode_valid_ctx succeeded and wrote
1000 	 * the &enum drm_mode_status value to @status, or a negative error
1001 	 * code otherwise.
1002 	 *
1003 	 */
1004 	int (*mode_valid_ctx)(struct drm_connector *connector,
1005 			      struct drm_display_mode *mode,
1006 			      struct drm_modeset_acquire_ctx *ctx,
1007 			      enum drm_mode_status *status);
1008 
1009 	/**
1010 	 * @best_encoder:
1011 	 *
1012 	 * This function should select the best encoder for the given connector.
1013 	 *
1014 	 * This function is used by both the atomic helpers (in the
1015 	 * drm_atomic_helper_check_modeset() function) and in the legacy CRTC
1016 	 * helpers.
1017 	 *
1018 	 * NOTE:
1019 	 *
1020 	 * In atomic drivers this function is called in the check phase of an
1021 	 * atomic update. The driver is not allowed to change or inspect
1022 	 * anything outside of arguments passed-in. Atomic drivers which need to
1023 	 * inspect dynamic configuration state should instead use
1024 	 * @atomic_best_encoder.
1025 	 *
1026 	 * You can leave this function to NULL if the connector is only
1027 	 * attached to a single encoder. In this case, the core will call
1028 	 * drm_connector_get_single_encoder() for you.
1029 	 *
1030 	 * RETURNS:
1031 	 *
1032 	 * Encoder that should be used for the given connector and connector
1033 	 * state, or NULL if no suitable encoder exists. Note that the helpers
1034 	 * will ensure that encoders aren't used twice, drivers should not check
1035 	 * for this.
1036 	 */
1037 	struct drm_encoder *(*best_encoder)(struct drm_connector *connector);
1038 
1039 	/**
1040 	 * @atomic_best_encoder:
1041 	 *
1042 	 * This is the atomic version of @best_encoder for atomic drivers which
1043 	 * need to select the best encoder depending upon the desired
1044 	 * configuration and can't select it statically.
1045 	 *
1046 	 * This function is used by drm_atomic_helper_check_modeset().
1047 	 * If it is not implemented, the core will fallback to @best_encoder
1048 	 * (or drm_connector_get_single_encoder() if @best_encoder is NULL).
1049 	 *
1050 	 * NOTE:
1051 	 *
1052 	 * This function is called in the check phase of an atomic update. The
1053 	 * driver is not allowed to change anything outside of the
1054 	 * &drm_atomic_state update tracking structure passed in.
1055 	 *
1056 	 * RETURNS:
1057 	 *
1058 	 * Encoder that should be used for the given connector and connector
1059 	 * state, or NULL if no suitable encoder exists. Note that the helpers
1060 	 * will ensure that encoders aren't used twice, drivers should not check
1061 	 * for this.
1062 	 */
1063 	struct drm_encoder *(*atomic_best_encoder)(struct drm_connector *connector,
1064 						   struct drm_atomic_state *state);
1065 
1066 	/**
1067 	 * @atomic_check:
1068 	 *
1069 	 * This hook is used to validate connector state. This function is
1070 	 * called from &drm_atomic_helper_check_modeset, and is called when
1071 	 * a connector property is set, or a modeset on the crtc is forced.
1072 	 *
1073 	 * Because &drm_atomic_helper_check_modeset may be called multiple times,
1074 	 * this function should handle being called multiple times as well.
1075 	 *
1076 	 * This function is also allowed to inspect any other object's state and
1077 	 * can add more state objects to the atomic commit if needed. Care must
1078 	 * be taken though to ensure that state check and compute functions for
1079 	 * these added states are all called, and derived state in other objects
1080 	 * all updated. Again the recommendation is to just call check helpers
1081 	 * until a maximal configuration is reached.
1082 	 *
1083 	 * NOTE:
1084 	 *
1085 	 * This function is called in the check phase of an atomic update. The
1086 	 * driver is not allowed to change anything outside of the free-standing
1087 	 * state objects passed-in or assembled in the overall &drm_atomic_state
1088 	 * update tracking structure.
1089 	 *
1090 	 * RETURNS:
1091 	 *
1092 	 * 0 on success, -EINVAL if the state or the transition can't be
1093 	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
1094 	 * attempt to obtain another state object ran into a &drm_modeset_lock
1095 	 * deadlock.
1096 	 */
1097 	int (*atomic_check)(struct drm_connector *connector,
1098 			    struct drm_atomic_state *state);
1099 
1100 	/**
1101 	 * @atomic_commit:
1102 	 *
1103 	 * This hook is to be used by drivers implementing writeback connectors
1104 	 * that need a point when to commit the writeback job to the hardware.
1105 	 * The writeback_job to commit is available in the new connector state,
1106 	 * in &drm_connector_state.writeback_job.
1107 	 *
1108 	 * This hook is optional.
1109 	 *
1110 	 * This callback is used by the atomic modeset helpers.
1111 	 */
1112 	void (*atomic_commit)(struct drm_connector *connector,
1113 			      struct drm_atomic_state *state);
1114 
1115 	/**
1116 	 * @prepare_writeback_job:
1117 	 *
1118 	 * As writeback jobs contain a framebuffer, drivers may need to
1119 	 * prepare and clean them up the same way they can prepare and
1120 	 * clean up framebuffers for planes. This optional connector operation
1121 	 * is used to support the preparation of writeback jobs. The job
1122 	 * prepare operation is called from drm_atomic_helper_prepare_planes()
1123 	 * for struct &drm_writeback_connector connectors only.
1124 	 *
1125 	 * This operation is optional.
1126 	 *
1127 	 * This callback is used by the atomic modeset helpers.
1128 	 */
1129 	int (*prepare_writeback_job)(struct drm_writeback_connector *connector,
1130 				     struct drm_writeback_job *job);
1131 	/**
1132 	 * @cleanup_writeback_job:
1133 	 *
1134 	 * This optional connector operation is used to support the
1135 	 * cleanup of writeback jobs. The job cleanup operation is called
1136 	 * from the existing drm_writeback_cleanup_job() function, invoked
1137 	 * both when destroying the job as part of an aborted commit, or when
1138 	 * the job completes.
1139 	 *
1140 	 * This operation is optional.
1141 	 *
1142 	 * This callback is used by the atomic modeset helpers.
1143 	 */
1144 	void (*cleanup_writeback_job)(struct drm_writeback_connector *connector,
1145 				      struct drm_writeback_job *job);
1146 };
1147 
1148 /**
1149  * drm_connector_helper_add - sets the helper vtable for a connector
1150  * @connector: DRM connector
1151  * @funcs: helper vtable to set for @connector
1152  */
1153 static inline void drm_connector_helper_add(struct drm_connector *connector,
1154 					    const struct drm_connector_helper_funcs *funcs)
1155 {
1156 	connector->helper_private = funcs;
1157 }
1158 
1159 /**
1160  * struct drm_plane_helper_funcs - helper operations for planes
1161  *
1162  * These functions are used by the atomic helpers and by the transitional plane
1163  * helpers.
1164  */
1165 struct drm_plane_helper_funcs {
1166 	/**
1167 	 * @prepare_fb:
1168 	 *
1169 	 * This hook is to prepare a framebuffer for scanout by e.g. pinning
1170 	 * its backing storage or relocating it into a contiguous block of
1171 	 * VRAM. Other possible preparatory work includes flushing caches.
1172 	 *
1173 	 * This function must not block for outstanding rendering, since it is
1174 	 * called in the context of the atomic IOCTL even for async commits to
1175 	 * be able to return any errors to userspace. Instead the recommended
1176 	 * way is to fill out the &drm_plane_state.fence of the passed-in
1177 	 * &drm_plane_state. If the driver doesn't support native fences then
1178 	 * equivalent functionality should be implemented through private
1179 	 * members in the plane structure.
1180 	 *
1181 	 * Drivers which always have their buffers pinned should use
1182 	 * drm_gem_plane_helper_prepare_fb() for this hook.
1183 	 *
1184 	 * The helpers will call @cleanup_fb with matching arguments for every
1185 	 * successful call to this hook.
1186 	 *
1187 	 * This callback is used by the atomic modeset helpers and by the
1188 	 * transitional plane helpers, but it is optional.
1189 	 *
1190 	 * RETURNS:
1191 	 *
1192 	 * 0 on success or one of the following negative error codes allowed by
1193 	 * the &drm_mode_config_funcs.atomic_commit vfunc. When using helpers
1194 	 * this callback is the only one which can fail an atomic commit,
1195 	 * everything else must complete successfully.
1196 	 */
1197 	int (*prepare_fb)(struct drm_plane *plane,
1198 			  struct drm_plane_state *new_state);
1199 	/**
1200 	 * @cleanup_fb:
1201 	 *
1202 	 * This hook is called to clean up any resources allocated for the given
1203 	 * framebuffer and plane configuration in @prepare_fb.
1204 	 *
1205 	 * This callback is used by the atomic modeset helpers and by the
1206 	 * transitional plane helpers, but it is optional.
1207 	 */
1208 	void (*cleanup_fb)(struct drm_plane *plane,
1209 			   struct drm_plane_state *old_state);
1210 
1211 	/**
1212 	 * @atomic_check:
1213 	 *
1214 	 * Drivers should check plane specific constraints in this hook.
1215 	 *
1216 	 * When using drm_atomic_helper_check_planes() plane's @atomic_check
1217 	 * hooks are called before the ones for CRTCs, which allows drivers to
1218 	 * request shared resources that the CRTC controls here. For more
1219 	 * complicated dependencies the driver can call the provided check helpers
1220 	 * multiple times until the computed state has a final configuration and
1221 	 * everything has been checked.
1222 	 *
1223 	 * This function is also allowed to inspect any other object's state and
1224 	 * can add more state objects to the atomic commit if needed. Care must
1225 	 * be taken though to ensure that state check and compute functions for
1226 	 * these added states are all called, and derived state in other objects
1227 	 * all updated. Again the recommendation is to just call check helpers
1228 	 * until a maximal configuration is reached.
1229 	 *
1230 	 * This callback is used by the atomic modeset helpers and by the
1231 	 * transitional plane helpers, but it is optional.
1232 	 *
1233 	 * NOTE:
1234 	 *
1235 	 * This function is called in the check phase of an atomic update. The
1236 	 * driver is not allowed to change anything outside of the
1237 	 * &drm_atomic_state update tracking structure.
1238 	 *
1239 	 * RETURNS:
1240 	 *
1241 	 * 0 on success, -EINVAL if the state or the transition can't be
1242 	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
1243 	 * attempt to obtain another state object ran into a &drm_modeset_lock
1244 	 * deadlock.
1245 	 */
1246 	int (*atomic_check)(struct drm_plane *plane,
1247 			    struct drm_atomic_state *state);
1248 
1249 	/**
1250 	 * @atomic_update:
1251 	 *
1252 	 * Drivers should use this function to update the plane state.  This
1253 	 * hook is called in-between the &drm_crtc_helper_funcs.atomic_begin and
1254 	 * drm_crtc_helper_funcs.atomic_flush callbacks.
1255 	 *
1256 	 * Note that the power state of the display pipe when this function is
1257 	 * called depends upon the exact helpers and calling sequence the driver
1258 	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
1259 	 * the tradeoffs and variants of plane commit helpers.
1260 	 *
1261 	 * This callback is used by the atomic modeset helpers and by the
1262 	 * transitional plane helpers, but it is optional.
1263 	 */
1264 	void (*atomic_update)(struct drm_plane *plane,
1265 			      struct drm_atomic_state *state);
1266 	/**
1267 	 * @atomic_disable:
1268 	 *
1269 	 * Drivers should use this function to unconditionally disable a plane.
1270 	 * This hook is called in-between the
1271 	 * &drm_crtc_helper_funcs.atomic_begin and
1272 	 * drm_crtc_helper_funcs.atomic_flush callbacks. It is an alternative to
1273 	 * @atomic_update, which will be called for disabling planes, too, if
1274 	 * the @atomic_disable hook isn't implemented.
1275 	 *
1276 	 * This hook is also useful to disable planes in preparation of a modeset,
1277 	 * by calling drm_atomic_helper_disable_planes_on_crtc() from the
1278 	 * &drm_crtc_helper_funcs.disable hook.
1279 	 *
1280 	 * Note that the power state of the display pipe when this function is
1281 	 * called depends upon the exact helpers and calling sequence the driver
1282 	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
1283 	 * the tradeoffs and variants of plane commit helpers.
1284 	 *
1285 	 * This callback is used by the atomic modeset helpers and by the
1286 	 * transitional plane helpers, but it is optional.
1287 	 */
1288 	void (*atomic_disable)(struct drm_plane *plane,
1289 			       struct drm_atomic_state *state);
1290 
1291 	/**
1292 	 * @atomic_async_check:
1293 	 *
1294 	 * Drivers should set this function pointer to check if the plane's
1295 	 * atomic state can be updated in a async fashion. Here async means
1296 	 * "not vblank synchronized".
1297 	 *
1298 	 * This hook is called by drm_atomic_async_check() to establish if a
1299 	 * given update can be committed asynchronously, that is, if it can
1300 	 * jump ahead of the state currently queued for update.
1301 	 *
1302 	 * RETURNS:
1303 	 *
1304 	 * Return 0 on success and any error returned indicates that the update
1305 	 * can not be applied in asynchronous manner.
1306 	 */
1307 	int (*atomic_async_check)(struct drm_plane *plane,
1308 				  struct drm_atomic_state *state);
1309 
1310 	/**
1311 	 * @atomic_async_update:
1312 	 *
1313 	 * Drivers should set this function pointer to perform asynchronous
1314 	 * updates of planes, that is, jump ahead of the currently queued
1315 	 * state and update the plane. Here async means "not vblank
1316 	 * synchronized".
1317 	 *
1318 	 * This hook is called by drm_atomic_helper_async_commit().
1319 	 *
1320 	 * An async update will happen on legacy cursor updates. An async
1321 	 * update won't happen if there is an outstanding commit modifying
1322 	 * the same plane.
1323 	 *
1324 	 * When doing async_update drivers shouldn't replace the
1325 	 * &drm_plane_state but update the current one with the new plane
1326 	 * configurations in the new plane_state.
1327 	 *
1328 	 * Drivers should also swap the framebuffers between current plane
1329 	 * state (&drm_plane.state) and new_state.
1330 	 * This is required since cleanup for async commits is performed on
1331 	 * the new state, rather than old state like for traditional commits.
1332 	 * Since we want to give up the reference on the current (old) fb
1333 	 * instead of our brand new one, swap them in the driver during the
1334 	 * async commit.
1335 	 *
1336 	 * FIXME:
1337 	 *  - It only works for single plane updates
1338 	 *  - Async Pageflips are not supported yet
1339 	 *  - Some hw might still scan out the old buffer until the next
1340 	 *    vblank, however we let go of the fb references as soon as
1341 	 *    we run this hook. For now drivers must implement their own workers
1342 	 *    for deferring if needed, until a common solution is created.
1343 	 */
1344 	void (*atomic_async_update)(struct drm_plane *plane,
1345 				    struct drm_atomic_state *state);
1346 };
1347 
1348 /**
1349  * drm_plane_helper_add - sets the helper vtable for a plane
1350  * @plane: DRM plane
1351  * @funcs: helper vtable to set for @plane
1352  */
1353 static inline void drm_plane_helper_add(struct drm_plane *plane,
1354 					const struct drm_plane_helper_funcs *funcs)
1355 {
1356 	plane->helper_private = funcs;
1357 }
1358 
1359 /**
1360  * struct drm_mode_config_helper_funcs - global modeset helper operations
1361  *
1362  * These helper functions are used by the atomic helpers.
1363  */
1364 struct drm_mode_config_helper_funcs {
1365 	/**
1366 	 * @atomic_commit_tail:
1367 	 *
1368 	 * This hook is used by the default atomic_commit() hook implemented in
1369 	 * drm_atomic_helper_commit() together with the nonblocking commit
1370 	 * helpers (see drm_atomic_helper_setup_commit() for a starting point)
1371 	 * to implement blocking and nonblocking commits easily. It is not used
1372 	 * by the atomic helpers
1373 	 *
1374 	 * This function is called when the new atomic state has already been
1375 	 * swapped into the various state pointers. The passed in state
1376 	 * therefore contains copies of the old/previous state. This hook should
1377 	 * commit the new state into hardware. Note that the helpers have
1378 	 * already waited for preceeding atomic commits and fences, but drivers
1379 	 * can add more waiting calls at the start of their implementation, e.g.
1380 	 * to wait for driver-internal request for implicit syncing, before
1381 	 * starting to commit the update to the hardware.
1382 	 *
1383 	 * After the atomic update is committed to the hardware this hook needs
1384 	 * to call drm_atomic_helper_commit_hw_done(). Then wait for the upate
1385 	 * to be executed by the hardware, for example using
1386 	 * drm_atomic_helper_wait_for_vblanks() or
1387 	 * drm_atomic_helper_wait_for_flip_done(), and then clean up the old
1388 	 * framebuffers using drm_atomic_helper_cleanup_planes().
1389 	 *
1390 	 * When disabling a CRTC this hook _must_ stall for the commit to
1391 	 * complete. Vblank waits don't work on disabled CRTC, hence the core
1392 	 * can't take care of this. And it also can't rely on the vblank event,
1393 	 * since that can be signalled already when the screen shows black,
1394 	 * which can happen much earlier than the last hardware access needed to
1395 	 * shut off the display pipeline completely.
1396 	 *
1397 	 * This hook is optional, the default implementation is
1398 	 * drm_atomic_helper_commit_tail().
1399 	 */
1400 	void (*atomic_commit_tail)(struct drm_atomic_state *state);
1401 
1402 	/**
1403 	 * @atomic_commit_setup:
1404 	 *
1405 	 * This hook is used by the default atomic_commit() hook implemented in
1406 	 * drm_atomic_helper_commit() together with the nonblocking helpers (see
1407 	 * drm_atomic_helper_setup_commit()) to extend the DRM commit setup. It
1408 	 * is not used by the atomic helpers.
1409 	 *
1410 	 * This function is called at the end of
1411 	 * drm_atomic_helper_setup_commit(), so once the commit has been
1412 	 * properly setup across the generic DRM object states. It allows
1413 	 * drivers to do some additional commit tracking that isn't related to a
1414 	 * CRTC, plane or connector, tracked in a &drm_private_obj structure.
1415 	 *
1416 	 * Note that the documentation of &drm_private_obj has more details on
1417 	 * how one should implement this.
1418 	 *
1419 	 * This hook is optional.
1420 	 */
1421 	int (*atomic_commit_setup)(struct drm_atomic_state *state);
1422 };
1423 
1424 #endif
1425