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 struct drm_writeback_connector;
52 struct drm_writeback_job;
53 
54 enum mode_set_atomic {
55 	LEAVE_ATOMIC_MODE_SET,
56 	ENTER_ATOMIC_MODE_SET,
57 };
58 
59 /**
60  * struct drm_crtc_helper_funcs - helper operations for CRTCs
61  *
62  * These hooks are used by the legacy CRTC helpers and the new atomic
63  * modesetting helpers.
64  */
65 struct drm_crtc_helper_funcs {
66 	/**
67 	 * @dpms:
68 	 *
69 	 * Callback to control power levels on the CRTC.  If the mode passed in
70 	 * is unsupported, the provider must use the next lowest power level.
71 	 * This is used by the legacy CRTC helpers to implement DPMS
72 	 * functionality in drm_helper_connector_dpms().
73 	 *
74 	 * This callback is also used to disable a CRTC by calling it with
75 	 * DRM_MODE_DPMS_OFF if the @disable hook isn't used.
76 	 *
77 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
78 	 * also support using this hook for enabling and disabling a CRTC to
79 	 * facilitate transitions to atomic, but it is deprecated. Instead
80 	 * @atomic_enable and @atomic_disable should be used.
81 	 */
82 	void (*dpms)(struct drm_crtc *crtc, int mode);
83 
84 	/**
85 	 * @prepare:
86 	 *
87 	 * This callback should prepare the CRTC for a subsequent modeset, which
88 	 * in practice means the driver should disable the CRTC if it is
89 	 * running. Most drivers ended up implementing this by calling their
90 	 * @dpms hook with DRM_MODE_DPMS_OFF.
91 	 *
92 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
93 	 * also support using this hook for disabling a CRTC to facilitate
94 	 * transitions to atomic, but it is deprecated. Instead @atomic_disable
95 	 * should be used.
96 	 */
97 	void (*prepare)(struct drm_crtc *crtc);
98 
99 	/**
100 	 * @commit:
101 	 *
102 	 * This callback should commit the new mode on the CRTC after a modeset,
103 	 * which in practice means the driver should enable the CRTC.  Most
104 	 * drivers ended up implementing this by calling their @dpms hook with
105 	 * DRM_MODE_DPMS_ON.
106 	 *
107 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
108 	 * also support using this hook for enabling a CRTC to facilitate
109 	 * transitions to atomic, but it is deprecated. Instead @atomic_enable
110 	 * should be used.
111 	 */
112 	void (*commit)(struct drm_crtc *crtc);
113 
114 	/**
115 	 * @mode_valid:
116 	 *
117 	 * This callback is used to check if a specific mode is valid in this
118 	 * crtc. This should be implemented if the crtc has some sort of
119 	 * restriction in the modes it can display. For example, a given crtc
120 	 * may be responsible to set a clock value. If the clock can not
121 	 * produce all the values for the available modes then this callback
122 	 * can be used to restrict the number of modes to only the ones that
123 	 * can be displayed.
124 	 *
125 	 * This hook is used by the probe helpers to filter the mode list in
126 	 * drm_helper_probe_single_connector_modes(), and it is used by the
127 	 * atomic helpers to validate modes supplied by userspace in
128 	 * drm_atomic_helper_check_modeset().
129 	 *
130 	 * This function is optional.
131 	 *
132 	 * NOTE:
133 	 *
134 	 * Since this function is both called from the check phase of an atomic
135 	 * commit, and the mode validation in the probe paths it is not allowed
136 	 * to look at anything else but the passed-in mode, and validate it
137 	 * against configuration-invariant hardward constraints. Any further
138 	 * limits which depend upon the configuration can only be checked in
139 	 * @mode_fixup or @atomic_check.
140 	 *
141 	 * RETURNS:
142 	 *
143 	 * drm_mode_status Enum
144 	 */
145 	enum drm_mode_status (*mode_valid)(struct drm_crtc *crtc,
146 					   const struct drm_display_mode *mode);
147 
148 	/**
149 	 * @mode_fixup:
150 	 *
151 	 * This callback is used to validate a mode. The parameter mode is the
152 	 * display mode that userspace requested, adjusted_mode is the mode the
153 	 * encoders need to be fed with. Note that this is the inverse semantics
154 	 * of the meaning for the &drm_encoder and &drm_bridge_funcs.mode_fixup
155 	 * vfunc. If the CRTC cannot support the requested conversion from mode
156 	 * to adjusted_mode it should reject the modeset. See also
157 	 * &drm_crtc_state.adjusted_mode for more details.
158 	 *
159 	 * This function is used by both legacy CRTC helpers and atomic helpers.
160 	 * With atomic helpers it is optional.
161 	 *
162 	 * NOTE:
163 	 *
164 	 * This function is called in the check phase of atomic modesets, which
165 	 * can be aborted for any reason (including on userspace's request to
166 	 * just check whether a configuration would be possible). Atomic drivers
167 	 * MUST NOT touch any persistent state (hardware or software) or data
168 	 * structures except the passed in adjusted_mode parameter.
169 	 *
170 	 * This is in contrast to the legacy CRTC helpers where this was
171 	 * allowed.
172 	 *
173 	 * Atomic drivers which need to inspect and adjust more state should
174 	 * instead use the @atomic_check callback, but note that they're not
175 	 * perfectly equivalent: @mode_valid is called from
176 	 * drm_atomic_helper_check_modeset(), but @atomic_check is called from
177 	 * drm_atomic_helper_check_planes(), because originally it was meant for
178 	 * plane update checks only.
179 	 *
180 	 * Also beware that userspace can request its own custom modes, neither
181 	 * core nor helpers filter modes to the list of probe modes reported by
182 	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
183 	 * that modes are filtered consistently put any CRTC constraints and
184 	 * limits checks into @mode_valid.
185 	 *
186 	 * RETURNS:
187 	 *
188 	 * True if an acceptable configuration is possible, false if the modeset
189 	 * operation should be rejected.
190 	 */
191 	bool (*mode_fixup)(struct drm_crtc *crtc,
192 			   const struct drm_display_mode *mode,
193 			   struct drm_display_mode *adjusted_mode);
194 
195 	/**
196 	 * @mode_set:
197 	 *
198 	 * This callback is used by the legacy CRTC helpers to set a new mode,
199 	 * position and framebuffer. Since it ties the primary plane to every
200 	 * mode change it is incompatible with universal plane support. And
201 	 * since it can't update other planes it's incompatible with atomic
202 	 * modeset support.
203 	 *
204 	 * This callback is only used by CRTC helpers and deprecated.
205 	 *
206 	 * RETURNS:
207 	 *
208 	 * 0 on success or a negative error code on failure.
209 	 */
210 	int (*mode_set)(struct drm_crtc *crtc, struct drm_display_mode *mode,
211 			struct drm_display_mode *adjusted_mode, int x, int y,
212 			struct drm_framebuffer *old_fb);
213 
214 	/**
215 	 * @mode_set_nofb:
216 	 *
217 	 * This callback is used to update the display mode of a CRTC without
218 	 * changing anything of the primary plane configuration. This fits the
219 	 * requirement of atomic and hence is used by the atomic helpers.
220 	 *
221 	 * Note that the display pipe is completely off when this function is
222 	 * called. Atomic drivers which need hardware to be running before they
223 	 * program the new display mode (e.g. because they implement runtime PM)
224 	 * should not use this hook. This is because the helper library calls
225 	 * this hook only once per mode change and not every time the display
226 	 * pipeline is suspended using either DPMS or the new "ACTIVE" property.
227 	 * Which means register values set in this callback might get reset when
228 	 * the CRTC is suspended, but not restored.  Such drivers should instead
229 	 * move all their CRTC setup into the @atomic_enable callback.
230 	 *
231 	 * This callback is optional.
232 	 */
233 	void (*mode_set_nofb)(struct drm_crtc *crtc);
234 
235 	/**
236 	 * @mode_set_base:
237 	 *
238 	 * This callback is used by the legacy CRTC helpers to set a new
239 	 * framebuffer and scanout position. It is optional and used as an
240 	 * optimized fast-path instead of a full mode set operation with all the
241 	 * resulting flickering. If it is not present
242 	 * drm_crtc_helper_set_config() will fall back to a full modeset, using
243 	 * the @mode_set callback. Since it can't update other planes it's
244 	 * incompatible with atomic modeset support.
245 	 *
246 	 * This callback is only used by the CRTC helpers and deprecated.
247 	 *
248 	 * RETURNS:
249 	 *
250 	 * 0 on success or a negative error code on failure.
251 	 */
252 	int (*mode_set_base)(struct drm_crtc *crtc, int x, int y,
253 			     struct drm_framebuffer *old_fb);
254 
255 	/**
256 	 * @mode_set_base_atomic:
257 	 *
258 	 * This callback is used by the fbdev helpers to set a new framebuffer
259 	 * and scanout without sleeping, i.e. from an atomic calling context. It
260 	 * is only used to implement kgdb support.
261 	 *
262 	 * This callback is optional and only needed for kgdb support in the fbdev
263 	 * helpers.
264 	 *
265 	 * RETURNS:
266 	 *
267 	 * 0 on success or a negative error code on failure.
268 	 */
269 	int (*mode_set_base_atomic)(struct drm_crtc *crtc,
270 				    struct drm_framebuffer *fb, int x, int y,
271 				    enum mode_set_atomic);
272 
273 	/**
274 	 * @disable:
275 	 *
276 	 * This callback should be used to disable the CRTC. With the atomic
277 	 * drivers it is called after all encoders connected to this CRTC have
278 	 * been shut off already using their own
279 	 * &drm_encoder_helper_funcs.disable hook. If that sequence is too
280 	 * simple drivers can just add their own hooks and call it from this
281 	 * CRTC callback here by looping over all encoders connected to it using
282 	 * for_each_encoder_on_crtc().
283 	 *
284 	 * This hook is used both by legacy CRTC helpers and atomic helpers.
285 	 * Atomic drivers don't need to implement it if there's no need to
286 	 * disable anything at the CRTC level. To ensure that runtime PM
287 	 * handling (using either DPMS or the new "ACTIVE" property) works
288 	 * @disable must be the inverse of @atomic_enable for atomic drivers.
289 	 * Atomic drivers should consider to use @atomic_disable instead of
290 	 * this one.
291 	 *
292 	 * NOTE:
293 	 *
294 	 * With legacy CRTC helpers there's a big semantic difference between
295 	 * @disable and other hooks (like @prepare or @dpms) used to shut down a
296 	 * CRTC: @disable is only called when also logically disabling the
297 	 * display pipeline and needs to release any resources acquired in
298 	 * @mode_set (like shared PLLs, or again release pinned framebuffers).
299 	 *
300 	 * Therefore @disable must be the inverse of @mode_set plus @commit for
301 	 * drivers still using legacy CRTC helpers, which is different from the
302 	 * rules under atomic.
303 	 */
304 	void (*disable)(struct drm_crtc *crtc);
305 
306 	/**
307 	 * @atomic_check:
308 	 *
309 	 * Drivers should check plane-update related CRTC constraints in this
310 	 * hook. They can also check mode related limitations but need to be
311 	 * aware of the calling order, since this hook is used by
312 	 * drm_atomic_helper_check_planes() whereas the preparations needed to
313 	 * check output routing and the display mode is done in
314 	 * drm_atomic_helper_check_modeset(). Therefore drivers that want to
315 	 * check output routing and display mode constraints in this callback
316 	 * must ensure that drm_atomic_helper_check_modeset() has been called
317 	 * beforehand. This is calling order used by the default helper
318 	 * implementation in drm_atomic_helper_check().
319 	 *
320 	 * When using drm_atomic_helper_check_planes() this hook is called
321 	 * after the &drm_plane_helper_funcs.atomic_check hook for planes, which
322 	 * allows drivers to assign shared resources requested by planes in this
323 	 * callback here. For more complicated dependencies the driver can call
324 	 * the provided check helpers multiple times until the computed state
325 	 * has a final configuration and everything has been checked.
326 	 *
327 	 * This function is also allowed to inspect any other object's state and
328 	 * can add more state objects to the atomic commit if needed. Care must
329 	 * be taken though to ensure that state check and compute functions for
330 	 * these added states are all called, and derived state in other objects
331 	 * all updated. Again the recommendation is to just call check helpers
332 	 * until a maximal configuration is reached.
333 	 *
334 	 * This callback is used by the atomic modeset helpers, but it is
335 	 * optional.
336 	 *
337 	 * NOTE:
338 	 *
339 	 * This function is called in the check phase of an atomic update. The
340 	 * driver is not allowed to change anything outside of the free-standing
341 	 * state object passed-in.
342 	 *
343 	 * Also beware that userspace can request its own custom modes, neither
344 	 * core nor helpers filter modes to the list of probe modes reported by
345 	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
346 	 * that modes are filtered consistently put any CRTC constraints and
347 	 * limits checks into @mode_valid.
348 	 *
349 	 * RETURNS:
350 	 *
351 	 * 0 on success, -EINVAL if the state or the transition can't be
352 	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
353 	 * attempt to obtain another state object ran into a &drm_modeset_lock
354 	 * deadlock.
355 	 */
356 	int (*atomic_check)(struct drm_crtc *crtc,
357 			    struct drm_atomic_state *state);
358 
359 	/**
360 	 * @atomic_begin:
361 	 *
362 	 * Drivers should prepare for an atomic update of multiple planes on
363 	 * a CRTC in this hook. Depending upon hardware this might be vblank
364 	 * evasion, blocking updates by setting bits or doing preparatory work
365 	 * for e.g. manual update display.
366 	 *
367 	 * This hook is called before any plane commit functions are called.
368 	 *
369 	 * Note that the power state of the display pipe when this function is
370 	 * called depends upon the exact helpers and calling sequence the driver
371 	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
372 	 * the tradeoffs and variants of plane commit helpers.
373 	 *
374 	 * This callback is used by the atomic modeset helpers, but it is
375 	 * optional.
376 	 */
377 	void (*atomic_begin)(struct drm_crtc *crtc,
378 			     struct drm_atomic_state *state);
379 	/**
380 	 * @atomic_flush:
381 	 *
382 	 * Drivers should finalize an atomic update of multiple planes on
383 	 * a CRTC in this hook. Depending upon hardware this might include
384 	 * checking that vblank evasion was successful, unblocking updates by
385 	 * setting bits or setting the GO bit to flush out all updates.
386 	 *
387 	 * Simple hardware or hardware with special requirements can commit and
388 	 * flush out all updates for all planes from this hook and forgo all the
389 	 * other commit hooks for plane updates.
390 	 *
391 	 * This hook is called after any plane commit functions are called.
392 	 *
393 	 * Note that the power state of the display pipe when this function is
394 	 * called depends upon the exact helpers and calling sequence the driver
395 	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
396 	 * the tradeoffs and variants of plane commit helpers.
397 	 *
398 	 * This callback is used by the atomic modeset helpers, but it is
399 	 * optional.
400 	 */
401 	void (*atomic_flush)(struct drm_crtc *crtc,
402 			     struct drm_atomic_state *state);
403 
404 	/**
405 	 * @atomic_enable:
406 	 *
407 	 * This callback should be used to enable the CRTC. With the atomic
408 	 * drivers it is called before all encoders connected to this CRTC are
409 	 * enabled through the encoder's own &drm_encoder_helper_funcs.enable
410 	 * hook.  If that sequence is too simple drivers can just add their own
411 	 * hooks and call it from this CRTC callback here by looping over all
412 	 * encoders connected to it using for_each_encoder_on_crtc().
413 	 *
414 	 * This hook is used only by atomic helpers, for symmetry with
415 	 * @atomic_disable. Atomic drivers don't need to implement it if there's
416 	 * no need to enable anything at the CRTC level. To ensure that runtime
417 	 * PM handling (using either DPMS or the new "ACTIVE" property) works
418 	 * @atomic_enable must be the inverse of @atomic_disable for atomic
419 	 * drivers.
420 	 *
421 	 * This function is optional.
422 	 */
423 	void (*atomic_enable)(struct drm_crtc *crtc,
424 			      struct drm_atomic_state *state);
425 
426 	/**
427 	 * @atomic_disable:
428 	 *
429 	 * This callback should be used to disable the CRTC. With the atomic
430 	 * drivers it is called after all encoders connected to this CRTC have
431 	 * been shut off already using their own
432 	 * &drm_encoder_helper_funcs.disable hook. If that sequence is too
433 	 * simple drivers can just add their own hooks and call it from this
434 	 * CRTC callback here by looping over all encoders connected to it using
435 	 * for_each_encoder_on_crtc().
436 	 *
437 	 * This hook is used only by atomic helpers. Atomic drivers don't
438 	 * need to implement it if there's no need to disable anything at the
439 	 * CRTC level.
440 	 *
441 	 * This function is optional.
442 	 */
443 	void (*atomic_disable)(struct drm_crtc *crtc,
444 			       struct drm_atomic_state *state);
445 
446 	/**
447 	 * @get_scanout_position:
448 	 *
449 	 * Called by vblank timestamping code.
450 	 *
451 	 * Returns the current display scanout position from a CRTC and an
452 	 * optional accurate ktime_get() timestamp of when the position was
453 	 * measured. Note that this is a helper callback which is only used
454 	 * if a driver uses drm_crtc_vblank_helper_get_vblank_timestamp()
455 	 * for the @drm_crtc_funcs.get_vblank_timestamp callback.
456 	 *
457 	 * Parameters:
458 	 *
459 	 * crtc:
460 	 *     The CRTC.
461 	 * in_vblank_irq:
462 	 *     True when called from drm_crtc_handle_vblank(). Some drivers
463 	 *     need to apply some workarounds for gpu-specific vblank irq
464 	 *     quirks if the flag is set.
465 	 * vpos:
466 	 *     Target location for current vertical scanout position.
467 	 * hpos:
468 	 *     Target location for current horizontal scanout position.
469 	 * stime:
470 	 *     Target location for timestamp taken immediately before
471 	 *     scanout position query. Can be NULL to skip timestamp.
472 	 * etime:
473 	 *     Target location for timestamp taken immediately after
474 	 *     scanout position query. Can be NULL to skip timestamp.
475 	 * mode:
476 	 *     Current display timings.
477 	 *
478 	 * Returns vpos as a positive number while in active scanout area.
479 	 * Returns vpos as a negative number inside vblank, counting the number
480 	 * of scanlines to go until end of vblank, e.g., -1 means "one scanline
481 	 * until start of active scanout / end of vblank."
482 	 *
483 	 * Returns:
484 	 *
485 	 * True on success, false if a reliable scanout position counter could
486 	 * not be read out.
487 	 */
488 	bool (*get_scanout_position)(struct drm_crtc *crtc,
489 				     bool in_vblank_irq, int *vpos, int *hpos,
490 				     ktime_t *stime, ktime_t *etime,
491 				     const struct drm_display_mode *mode);
492 };
493 
494 /**
495  * drm_crtc_helper_add - sets the helper vtable for a crtc
496  * @crtc: DRM CRTC
497  * @funcs: helper vtable to set for @crtc
498  */
499 static inline void drm_crtc_helper_add(struct drm_crtc *crtc,
500 				       const struct drm_crtc_helper_funcs *funcs)
501 {
502 	crtc->helper_private = funcs;
503 }
504 
505 /**
506  * struct drm_encoder_helper_funcs - helper operations for encoders
507  *
508  * These hooks are used by the legacy CRTC helpers and the new atomic
509  * modesetting helpers.
510  */
511 struct drm_encoder_helper_funcs {
512 	/**
513 	 * @dpms:
514 	 *
515 	 * Callback to control power levels on the encoder.  If the mode passed in
516 	 * is unsupported, the provider must use the next lowest power level.
517 	 * This is used by the legacy encoder helpers to implement DPMS
518 	 * functionality in drm_helper_connector_dpms().
519 	 *
520 	 * This callback is also used to disable an encoder by calling it with
521 	 * DRM_MODE_DPMS_OFF if the @disable hook isn't used.
522 	 *
523 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
524 	 * also support using this hook for enabling and disabling an encoder to
525 	 * facilitate transitions to atomic, but it is deprecated. Instead
526 	 * @enable and @disable should be used.
527 	 */
528 	void (*dpms)(struct drm_encoder *encoder, int mode);
529 
530 	/**
531 	 * @mode_valid:
532 	 *
533 	 * This callback is used to check if a specific mode is valid in this
534 	 * encoder. This should be implemented if the encoder has some sort
535 	 * of restriction in the modes it can display. For example, a given
536 	 * encoder may be responsible to set a clock value. If the clock can
537 	 * not produce all the values for the available modes then this callback
538 	 * can be used to restrict the number of modes to only the ones that
539 	 * can be displayed.
540 	 *
541 	 * This hook is used by the probe helpers to filter the mode list in
542 	 * drm_helper_probe_single_connector_modes(), and it is used by the
543 	 * atomic helpers to validate modes supplied by userspace in
544 	 * drm_atomic_helper_check_modeset().
545 	 *
546 	 * This function is optional.
547 	 *
548 	 * NOTE:
549 	 *
550 	 * Since this function is both called from the check phase of an atomic
551 	 * commit, and the mode validation in the probe paths it is not allowed
552 	 * to look at anything else but the passed-in mode, and validate it
553 	 * against configuration-invariant hardward constraints. Any further
554 	 * limits which depend upon the configuration can only be checked in
555 	 * @mode_fixup or @atomic_check.
556 	 *
557 	 * RETURNS:
558 	 *
559 	 * drm_mode_status Enum
560 	 */
561 	enum drm_mode_status (*mode_valid)(struct drm_encoder *crtc,
562 					   const struct drm_display_mode *mode);
563 
564 	/**
565 	 * @mode_fixup:
566 	 *
567 	 * This callback is used to validate and adjust a mode. The parameter
568 	 * mode is the display mode that should be fed to the next element in
569 	 * the display chain, either the final &drm_connector or a &drm_bridge.
570 	 * The parameter adjusted_mode is the input mode the encoder requires. It
571 	 * can be modified by this callback and does not need to match mode. See
572 	 * also &drm_crtc_state.adjusted_mode for more details.
573 	 *
574 	 * This function is used by both legacy CRTC helpers and atomic helpers.
575 	 * This hook is optional.
576 	 *
577 	 * NOTE:
578 	 *
579 	 * This function is called in the check phase of atomic modesets, which
580 	 * can be aborted for any reason (including on userspace's request to
581 	 * just check whether a configuration would be possible). Atomic drivers
582 	 * MUST NOT touch any persistent state (hardware or software) or data
583 	 * structures except the passed in adjusted_mode parameter.
584 	 *
585 	 * This is in contrast to the legacy CRTC helpers where this was
586 	 * allowed.
587 	 *
588 	 * Atomic drivers which need to inspect and adjust more state should
589 	 * instead use the @atomic_check callback. If @atomic_check is used,
590 	 * this hook isn't called since @atomic_check allows a strict superset
591 	 * of the functionality of @mode_fixup.
592 	 *
593 	 * Also beware that userspace can request its own custom modes, neither
594 	 * core nor helpers filter modes to the list of probe modes reported by
595 	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
596 	 * that modes are filtered consistently put any encoder constraints and
597 	 * limits checks into @mode_valid.
598 	 *
599 	 * RETURNS:
600 	 *
601 	 * True if an acceptable configuration is possible, false if the modeset
602 	 * operation should be rejected.
603 	 */
604 	bool (*mode_fixup)(struct drm_encoder *encoder,
605 			   const struct drm_display_mode *mode,
606 			   struct drm_display_mode *adjusted_mode);
607 
608 	/**
609 	 * @prepare:
610 	 *
611 	 * This callback should prepare the encoder for a subsequent modeset,
612 	 * which in practice means the driver should disable the encoder if it
613 	 * is running. Most drivers ended up implementing this by calling their
614 	 * @dpms hook with DRM_MODE_DPMS_OFF.
615 	 *
616 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
617 	 * also support using this hook for disabling an encoder to facilitate
618 	 * transitions to atomic, but it is deprecated. Instead @disable should
619 	 * be used.
620 	 */
621 	void (*prepare)(struct drm_encoder *encoder);
622 
623 	/**
624 	 * @commit:
625 	 *
626 	 * This callback should commit the new mode on the encoder after a modeset,
627 	 * which in practice means the driver should enable the encoder.  Most
628 	 * drivers ended up implementing this by calling their @dpms hook with
629 	 * DRM_MODE_DPMS_ON.
630 	 *
631 	 * This callback is used by the legacy CRTC helpers.  Atomic helpers
632 	 * also support using this hook for enabling an encoder to facilitate
633 	 * transitions to atomic, but it is deprecated. Instead @enable should
634 	 * be used.
635 	 */
636 	void (*commit)(struct drm_encoder *encoder);
637 
638 	/**
639 	 * @mode_set:
640 	 *
641 	 * This callback is used to update the display mode of an encoder.
642 	 *
643 	 * Note that the display pipe is completely off when this function is
644 	 * called. Drivers which need hardware to be running before they program
645 	 * the new display mode (because they implement runtime PM) should not
646 	 * use this hook, because the helper library calls it only once and not
647 	 * every time the display pipeline is suspend using either DPMS or the
648 	 * new "ACTIVE" property. Such drivers should instead move all their
649 	 * encoder setup into the @enable callback.
650 	 *
651 	 * This callback is used both by the legacy CRTC helpers and the atomic
652 	 * modeset helpers. It is optional in the atomic helpers.
653 	 *
654 	 * NOTE:
655 	 *
656 	 * If the driver uses the atomic modeset helpers and needs to inspect
657 	 * the connector state or connector display info during mode setting,
658 	 * @atomic_mode_set can be used instead.
659 	 */
660 	void (*mode_set)(struct drm_encoder *encoder,
661 			 struct drm_display_mode *mode,
662 			 struct drm_display_mode *adjusted_mode);
663 
664 	/**
665 	 * @atomic_mode_set:
666 	 *
667 	 * This callback is used to update the display mode of an encoder.
668 	 *
669 	 * Note that the display pipe is completely off when this function is
670 	 * called. Drivers which need hardware to be running before they program
671 	 * the new display mode (because they implement runtime PM) should not
672 	 * use this hook, because the helper library calls it only once and not
673 	 * every time the display pipeline is suspended using either DPMS or the
674 	 * new "ACTIVE" property. Such drivers should instead move all their
675 	 * encoder setup into the @enable callback.
676 	 *
677 	 * This callback is used by the atomic modeset helpers in place of the
678 	 * @mode_set callback, if set by the driver. It is optional and should
679 	 * be used instead of @mode_set if the driver needs to inspect the
680 	 * connector state or display info, since there is no direct way to
681 	 * go from the encoder to the current connector.
682 	 */
683 	void (*atomic_mode_set)(struct drm_encoder *encoder,
684 				struct drm_crtc_state *crtc_state,
685 				struct drm_connector_state *conn_state);
686 
687 	/**
688 	 * @detect:
689 	 *
690 	 * This callback can be used by drivers who want to do detection on the
691 	 * encoder object instead of in connector functions.
692 	 *
693 	 * It is not used by any helper and therefore has purely driver-specific
694 	 * semantics. New drivers shouldn't use this and instead just implement
695 	 * their own private callbacks.
696 	 *
697 	 * FIXME:
698 	 *
699 	 * This should just be converted into a pile of driver vfuncs.
700 	 * Currently radeon, amdgpu and nouveau are using it.
701 	 */
702 	enum drm_connector_status (*detect)(struct drm_encoder *encoder,
703 					    struct drm_connector *connector);
704 
705 	/**
706 	 * @atomic_disable:
707 	 *
708 	 * This callback should be used to disable the encoder. With the atomic
709 	 * drivers it is called before this encoder's CRTC has been shut off
710 	 * using their own &drm_crtc_helper_funcs.atomic_disable hook. If that
711 	 * sequence is too simple drivers can just add their own driver private
712 	 * encoder hooks and call them from CRTC's callback by looping over all
713 	 * encoders connected to it using for_each_encoder_on_crtc().
714 	 *
715 	 * This callback is a variant of @disable that provides the atomic state
716 	 * to the driver. If @atomic_disable is implemented, @disable is not
717 	 * called by the helpers.
718 	 *
719 	 * This hook is only used by atomic helpers. Atomic drivers don't need
720 	 * to implement it if there's no need to disable anything at the encoder
721 	 * level. To ensure that runtime PM handling (using either DPMS or the
722 	 * new "ACTIVE" property) works @atomic_disable must be the inverse of
723 	 * @atomic_enable.
724 	 */
725 	void (*atomic_disable)(struct drm_encoder *encoder,
726 			       struct drm_atomic_state *state);
727 
728 	/**
729 	 * @atomic_enable:
730 	 *
731 	 * This callback should be used to enable the encoder. It is called
732 	 * after this encoder's CRTC has been enabled using their own
733 	 * &drm_crtc_helper_funcs.atomic_enable hook. If that sequence is
734 	 * too simple drivers can just add their own driver private encoder
735 	 * hooks and call them from CRTC's callback by looping over all encoders
736 	 * connected to it using for_each_encoder_on_crtc().
737 	 *
738 	 * This callback is a variant of @enable that provides the atomic state
739 	 * to the driver. If @atomic_enable is implemented, @enable is not
740 	 * called by the helpers.
741 	 *
742 	 * This hook is only used by atomic helpers, it is the opposite of
743 	 * @atomic_disable. Atomic drivers don't need to implement it if there's
744 	 * no need to enable anything at the encoder level. To ensure that
745 	 * runtime PM handling works @atomic_enable must be the inverse of
746 	 * @atomic_disable.
747 	 */
748 	void (*atomic_enable)(struct drm_encoder *encoder,
749 			      struct drm_atomic_state *state);
750 
751 	/**
752 	 * @disable:
753 	 *
754 	 * This callback should be used to disable the encoder. With the atomic
755 	 * drivers it is called before this encoder's CRTC has been shut off
756 	 * using their own &drm_crtc_helper_funcs.disable hook.  If that
757 	 * sequence is too simple drivers can just add their own driver private
758 	 * encoder hooks and call them from CRTC's callback by looping over all
759 	 * encoders connected to it using for_each_encoder_on_crtc().
760 	 *
761 	 * This hook is used both by legacy CRTC helpers and atomic helpers.
762 	 * Atomic drivers don't need to implement it if there's no need to
763 	 * disable anything at the encoder level. To ensure that runtime PM
764 	 * handling (using either DPMS or the new "ACTIVE" property) works
765 	 * @disable must be the inverse of @enable for atomic drivers.
766 	 *
767 	 * For atomic drivers also consider @atomic_disable and save yourself
768 	 * from having to read the NOTE below!
769 	 *
770 	 * NOTE:
771 	 *
772 	 * With legacy CRTC helpers there's a big semantic difference between
773 	 * @disable and other hooks (like @prepare or @dpms) used to shut down a
774 	 * encoder: @disable is only called when also logically disabling the
775 	 * display pipeline and needs to release any resources acquired in
776 	 * @mode_set (like shared PLLs, or again release pinned framebuffers).
777 	 *
778 	 * Therefore @disable must be the inverse of @mode_set plus @commit for
779 	 * drivers still using legacy CRTC helpers, which is different from the
780 	 * rules under atomic.
781 	 */
782 	void (*disable)(struct drm_encoder *encoder);
783 
784 	/**
785 	 * @enable:
786 	 *
787 	 * This callback should be used to enable the encoder. With the atomic
788 	 * drivers it is called after this encoder's CRTC has been enabled using
789 	 * their own &drm_crtc_helper_funcs.enable hook.  If that sequence is
790 	 * too simple drivers can just add their own driver private encoder
791 	 * hooks and call them from CRTC's callback by looping over all encoders
792 	 * connected to it using for_each_encoder_on_crtc().
793 	 *
794 	 * This hook is only used by atomic helpers, it is the opposite of
795 	 * @disable. Atomic drivers don't need to implement it if there's no
796 	 * need to enable anything at the encoder level. To ensure that
797 	 * runtime PM handling (using either DPMS or the new "ACTIVE" property)
798 	 * works @enable must be the inverse of @disable for atomic drivers.
799 	 */
800 	void (*enable)(struct drm_encoder *encoder);
801 
802 	/**
803 	 * @atomic_check:
804 	 *
805 	 * This callback is used to validate encoder state for atomic drivers.
806 	 * Since the encoder is the object connecting the CRTC and connector it
807 	 * gets passed both states, to be able to validate interactions and
808 	 * update the CRTC to match what the encoder needs for the requested
809 	 * connector.
810 	 *
811 	 * Since this provides a strict superset of the functionality of
812 	 * @mode_fixup (the requested and adjusted modes are both available
813 	 * through the passed in &struct drm_crtc_state) @mode_fixup is not
814 	 * called when @atomic_check is implemented.
815 	 *
816 	 * This function is used by the atomic helpers, but it is optional.
817 	 *
818 	 * NOTE:
819 	 *
820 	 * This function is called in the check phase of an atomic update. The
821 	 * driver is not allowed to change anything outside of the free-standing
822 	 * state objects passed-in or assembled in the overall &drm_atomic_state
823 	 * update tracking structure.
824 	 *
825 	 * Also beware that userspace can request its own custom modes, neither
826 	 * core nor helpers filter modes to the list of probe modes reported by
827 	 * the GETCONNECTOR IOCTL and stored in &drm_connector.modes. To ensure
828 	 * that modes are filtered consistently put any encoder constraints and
829 	 * limits checks into @mode_valid.
830 	 *
831 	 * RETURNS:
832 	 *
833 	 * 0 on success, -EINVAL if the state or the transition can't be
834 	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
835 	 * attempt to obtain another state object ran into a &drm_modeset_lock
836 	 * deadlock.
837 	 */
838 	int (*atomic_check)(struct drm_encoder *encoder,
839 			    struct drm_crtc_state *crtc_state,
840 			    struct drm_connector_state *conn_state);
841 };
842 
843 /**
844  * drm_encoder_helper_add - sets the helper vtable for an encoder
845  * @encoder: DRM encoder
846  * @funcs: helper vtable to set for @encoder
847  */
848 static inline void drm_encoder_helper_add(struct drm_encoder *encoder,
849 					  const struct drm_encoder_helper_funcs *funcs)
850 {
851 	encoder->helper_private = funcs;
852 }
853 
854 /**
855  * struct drm_connector_helper_funcs - helper operations for connectors
856  *
857  * These functions are used by the atomic and legacy modeset helpers and by the
858  * probe helpers.
859  */
860 struct drm_connector_helper_funcs {
861 	/**
862 	 * @get_modes:
863 	 *
864 	 * This function should fill in all modes currently valid for the sink
865 	 * into the &drm_connector.probed_modes list. It should also update the
866 	 * EDID property by calling drm_connector_update_edid_property().
867 	 *
868 	 * The usual way to implement this is to cache the EDID retrieved in the
869 	 * probe callback somewhere in the driver-private connector structure.
870 	 * In this function drivers then parse the modes in the EDID and add
871 	 * them by calling drm_add_edid_modes(). But connectors that drive a
872 	 * fixed panel can also manually add specific modes using
873 	 * drm_mode_probed_add(). Drivers which manually add modes should also
874 	 * make sure that the &drm_connector.display_info,
875 	 * &drm_connector.width_mm and &drm_connector.height_mm fields are
876 	 * filled in.
877 	 *
878 	 * Note that the caller function will automatically add standard VESA
879 	 * DMT modes up to 1024x768 if the .get_modes() helper operation returns
880 	 * no mode and if the connector status is connector_status_connected or
881 	 * connector_status_unknown. There is no need to call
882 	 * drm_add_modes_noedid() manually in that case.
883 	 *
884 	 * Virtual drivers that just want some standard VESA mode with a given
885 	 * resolution can call drm_add_modes_noedid(), and mark the preferred
886 	 * one using drm_set_preferred_mode().
887 	 *
888 	 * This function is only called after the @detect hook has indicated
889 	 * that a sink is connected and when the EDID isn't overridden through
890 	 * sysfs or the kernel commandline.
891 	 *
892 	 * This callback is used by the probe helpers in e.g.
893 	 * drm_helper_probe_single_connector_modes().
894 	 *
895 	 * To avoid races with concurrent connector state updates, the helper
896 	 * libraries always call this with the &drm_mode_config.connection_mutex
897 	 * held. Because of this it's safe to inspect &drm_connector->state.
898 	 *
899 	 * RETURNS:
900 	 *
901 	 * The number of modes added by calling drm_mode_probed_add(). Return 0
902 	 * on failures (no modes) instead of negative error codes.
903 	 */
904 	int (*get_modes)(struct drm_connector *connector);
905 
906 	/**
907 	 * @detect_ctx:
908 	 *
909 	 * Check to see if anything is attached to the connector. The parameter
910 	 * force is set to false whilst polling, true when checking the
911 	 * connector due to a user request. force can be used by the driver to
912 	 * avoid expensive, destructive operations during automated probing.
913 	 *
914 	 * This callback is optional, if not implemented the connector will be
915 	 * considered as always being attached.
916 	 *
917 	 * This is the atomic version of &drm_connector_funcs.detect.
918 	 *
919 	 * To avoid races against concurrent connector state updates, the
920 	 * helper libraries always call this with ctx set to a valid context,
921 	 * and &drm_mode_config.connection_mutex will always be locked with
922 	 * the ctx parameter set to this ctx. This allows taking additional
923 	 * locks as required.
924 	 *
925 	 * RETURNS:
926 	 *
927 	 * &drm_connector_status indicating the connector's status,
928 	 * or the error code returned by drm_modeset_lock(), -EDEADLK.
929 	 */
930 	int (*detect_ctx)(struct drm_connector *connector,
931 			  struct drm_modeset_acquire_ctx *ctx,
932 			  bool force);
933 
934 	/**
935 	 * @mode_valid:
936 	 *
937 	 * Callback to validate a mode for a connector, irrespective of the
938 	 * specific display configuration.
939 	 *
940 	 * This callback is used by the probe helpers to filter the mode list
941 	 * (which is usually derived from the EDID data block from the sink).
942 	 * See e.g. drm_helper_probe_single_connector_modes().
943 	 *
944 	 * This function is optional.
945 	 *
946 	 * NOTE:
947 	 *
948 	 * This only filters the mode list supplied to userspace in the
949 	 * GETCONNECTOR IOCTL. Compared to &drm_encoder_helper_funcs.mode_valid,
950 	 * &drm_crtc_helper_funcs.mode_valid and &drm_bridge_funcs.mode_valid,
951 	 * which are also called by the atomic helpers from
952 	 * drm_atomic_helper_check_modeset(). This allows userspace to force and
953 	 * ignore sink constraint (like the pixel clock limits in the screen's
954 	 * EDID), which is useful for e.g. testing, or working around a broken
955 	 * EDID. Any source hardware constraint (which always need to be
956 	 * enforced) therefore should be checked in one of the above callbacks,
957 	 * and not this one here.
958 	 *
959 	 * To avoid races with concurrent connector state updates, the helper
960 	 * libraries always call this with the &drm_mode_config.connection_mutex
961 	 * held. Because of this it's safe to inspect &drm_connector->state.
962          *
963 	 * RETURNS:
964 	 *
965 	 * Either &drm_mode_status.MODE_OK or one of the failure reasons in &enum
966 	 * drm_mode_status.
967 	 */
968 	enum drm_mode_status (*mode_valid)(struct drm_connector *connector,
969 					   struct drm_display_mode *mode);
970 
971 	/**
972 	 * @mode_valid_ctx:
973 	 *
974 	 * Callback to validate a mode for a connector, irrespective of the
975 	 * specific display configuration.
976 	 *
977 	 * This callback is used by the probe helpers to filter the mode list
978 	 * (which is usually derived from the EDID data block from the sink).
979 	 * See e.g. drm_helper_probe_single_connector_modes().
980 	 *
981 	 * This function is optional, and is the atomic version of
982 	 * &drm_connector_helper_funcs.mode_valid.
983 	 *
984 	 * To allow for accessing the atomic state of modesetting objects, the
985 	 * helper libraries always call this with ctx set to a valid context,
986 	 * and &drm_mode_config.connection_mutex will always be locked with
987 	 * the ctx parameter set to @ctx. This allows for taking additional
988 	 * locks as required.
989 	 *
990 	 * Even though additional locks may be acquired, this callback is
991 	 * still expected not to take any constraints into account which would
992 	 * be influenced by the currently set display state - such constraints
993 	 * should be handled in the driver's atomic check. For example, if a
994 	 * connector shares display bandwidth with other connectors then it
995 	 * would be ok to validate the minimum bandwidth requirement of a mode
996 	 * against the maximum possible bandwidth of the connector. But it
997 	 * wouldn't be ok to take the current bandwidth usage of other
998 	 * connectors into account, as this would change depending on the
999 	 * display state.
1000 	 *
1001 	 * Returns:
1002 	 * 0 if &drm_connector_helper_funcs.mode_valid_ctx succeeded and wrote
1003 	 * the &enum drm_mode_status value to @status, or a negative error
1004 	 * code otherwise.
1005 	 *
1006 	 */
1007 	int (*mode_valid_ctx)(struct drm_connector *connector,
1008 			      struct drm_display_mode *mode,
1009 			      struct drm_modeset_acquire_ctx *ctx,
1010 			      enum drm_mode_status *status);
1011 
1012 	/**
1013 	 * @best_encoder:
1014 	 *
1015 	 * This function should select the best encoder for the given connector.
1016 	 *
1017 	 * This function is used by both the atomic helpers (in the
1018 	 * drm_atomic_helper_check_modeset() function) and in the legacy CRTC
1019 	 * helpers.
1020 	 *
1021 	 * NOTE:
1022 	 *
1023 	 * In atomic drivers this function is called in the check phase of an
1024 	 * atomic update. The driver is not allowed to change or inspect
1025 	 * anything outside of arguments passed-in. Atomic drivers which need to
1026 	 * inspect dynamic configuration state should instead use
1027 	 * @atomic_best_encoder.
1028 	 *
1029 	 * You can leave this function to NULL if the connector is only
1030 	 * attached to a single encoder. In this case, the core will call
1031 	 * drm_connector_get_single_encoder() for you.
1032 	 *
1033 	 * RETURNS:
1034 	 *
1035 	 * Encoder that should be used for the given connector and connector
1036 	 * state, or NULL if no suitable encoder exists. Note that the helpers
1037 	 * will ensure that encoders aren't used twice, drivers should not check
1038 	 * for this.
1039 	 */
1040 	struct drm_encoder *(*best_encoder)(struct drm_connector *connector);
1041 
1042 	/**
1043 	 * @atomic_best_encoder:
1044 	 *
1045 	 * This is the atomic version of @best_encoder for atomic drivers which
1046 	 * need to select the best encoder depending upon the desired
1047 	 * configuration and can't select it statically.
1048 	 *
1049 	 * This function is used by drm_atomic_helper_check_modeset().
1050 	 * If it is not implemented, the core will fallback to @best_encoder
1051 	 * (or drm_connector_get_single_encoder() if @best_encoder is NULL).
1052 	 *
1053 	 * NOTE:
1054 	 *
1055 	 * This function is called in the check phase of an atomic update. The
1056 	 * driver is not allowed to change anything outside of the
1057 	 * &drm_atomic_state update tracking structure passed in.
1058 	 *
1059 	 * RETURNS:
1060 	 *
1061 	 * Encoder that should be used for the given connector and connector
1062 	 * state, or NULL if no suitable encoder exists. Note that the helpers
1063 	 * will ensure that encoders aren't used twice, drivers should not check
1064 	 * for this.
1065 	 */
1066 	struct drm_encoder *(*atomic_best_encoder)(struct drm_connector *connector,
1067 						   struct drm_atomic_state *state);
1068 
1069 	/**
1070 	 * @atomic_check:
1071 	 *
1072 	 * This hook is used to validate connector state. This function is
1073 	 * called from &drm_atomic_helper_check_modeset, and is called when
1074 	 * a connector property is set, or a modeset on the crtc is forced.
1075 	 *
1076 	 * Because &drm_atomic_helper_check_modeset may be called multiple times,
1077 	 * this function should handle being called multiple times as well.
1078 	 *
1079 	 * This function is also allowed to inspect any other object's state and
1080 	 * can add more state objects to the atomic commit if needed. Care must
1081 	 * be taken though to ensure that state check and compute functions for
1082 	 * these added states are all called, and derived state in other objects
1083 	 * all updated. Again the recommendation is to just call check helpers
1084 	 * until a maximal configuration is reached.
1085 	 *
1086 	 * NOTE:
1087 	 *
1088 	 * This function is called in the check phase of an atomic update. The
1089 	 * driver is not allowed to change anything outside of the free-standing
1090 	 * state objects passed-in or assembled in the overall &drm_atomic_state
1091 	 * update tracking structure.
1092 	 *
1093 	 * RETURNS:
1094 	 *
1095 	 * 0 on success, -EINVAL if the state or the transition can't be
1096 	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
1097 	 * attempt to obtain another state object ran into a &drm_modeset_lock
1098 	 * deadlock.
1099 	 */
1100 	int (*atomic_check)(struct drm_connector *connector,
1101 			    struct drm_atomic_state *state);
1102 
1103 	/**
1104 	 * @atomic_commit:
1105 	 *
1106 	 * This hook is to be used by drivers implementing writeback connectors
1107 	 * that need a point when to commit the writeback job to the hardware.
1108 	 * The writeback_job to commit is available in the new connector state,
1109 	 * in &drm_connector_state.writeback_job.
1110 	 *
1111 	 * This hook is optional.
1112 	 *
1113 	 * This callback is used by the atomic modeset helpers.
1114 	 */
1115 	void (*atomic_commit)(struct drm_connector *connector,
1116 			      struct drm_atomic_state *state);
1117 
1118 	/**
1119 	 * @prepare_writeback_job:
1120 	 *
1121 	 * As writeback jobs contain a framebuffer, drivers may need to
1122 	 * prepare and clean them up the same way they can prepare and
1123 	 * clean up framebuffers for planes. This optional connector operation
1124 	 * is used to support the preparation of writeback jobs. The job
1125 	 * prepare operation is called from drm_atomic_helper_prepare_planes()
1126 	 * for struct &drm_writeback_connector connectors only.
1127 	 *
1128 	 * This operation is optional.
1129 	 *
1130 	 * This callback is used by the atomic modeset helpers.
1131 	 */
1132 	int (*prepare_writeback_job)(struct drm_writeback_connector *connector,
1133 				     struct drm_writeback_job *job);
1134 	/**
1135 	 * @cleanup_writeback_job:
1136 	 *
1137 	 * This optional connector operation is used to support the
1138 	 * cleanup of writeback jobs. The job cleanup operation is called
1139 	 * from the existing drm_writeback_cleanup_job() function, invoked
1140 	 * both when destroying the job as part of an aborted commit, or when
1141 	 * the job completes.
1142 	 *
1143 	 * This operation is optional.
1144 	 *
1145 	 * This callback is used by the atomic modeset helpers.
1146 	 */
1147 	void (*cleanup_writeback_job)(struct drm_writeback_connector *connector,
1148 				      struct drm_writeback_job *job);
1149 
1150 	/**
1151 	 * @enable_hpd:
1152 	 *
1153 	 * Enable hot-plug detection for the connector.
1154 	 *
1155 	 * This operation is optional.
1156 	 *
1157 	 * This callback is used by the drm_kms_helper_poll_enable() helpers.
1158 	 */
1159 	void (*enable_hpd)(struct drm_connector *connector);
1160 
1161 	/**
1162 	 * @disable_hpd:
1163 	 *
1164 	 * Disable hot-plug detection for the connector.
1165 	 *
1166 	 * This operation is optional.
1167 	 *
1168 	 * This callback is used by the drm_kms_helper_poll_disable() helpers.
1169 	 */
1170 	void (*disable_hpd)(struct drm_connector *connector);
1171 };
1172 
1173 /**
1174  * drm_connector_helper_add - sets the helper vtable for a connector
1175  * @connector: DRM connector
1176  * @funcs: helper vtable to set for @connector
1177  */
1178 static inline void drm_connector_helper_add(struct drm_connector *connector,
1179 					    const struct drm_connector_helper_funcs *funcs)
1180 {
1181 	connector->helper_private = funcs;
1182 }
1183 
1184 /**
1185  * struct drm_plane_helper_funcs - helper operations for planes
1186  *
1187  * These functions are used by the atomic helpers.
1188  */
1189 struct drm_plane_helper_funcs {
1190 	/**
1191 	 * @prepare_fb:
1192 	 *
1193 	 * This hook is to prepare a framebuffer for scanout by e.g. pinning
1194 	 * its backing storage or relocating it into a contiguous block of
1195 	 * VRAM. Other possible preparatory work includes flushing caches.
1196 	 *
1197 	 * This function must not block for outstanding rendering, since it is
1198 	 * called in the context of the atomic IOCTL even for async commits to
1199 	 * be able to return any errors to userspace. Instead the recommended
1200 	 * way is to fill out the &drm_plane_state.fence of the passed-in
1201 	 * &drm_plane_state. If the driver doesn't support native fences then
1202 	 * equivalent functionality should be implemented through private
1203 	 * members in the plane structure.
1204 	 *
1205 	 * For GEM drivers who neither have a @prepare_fb nor @cleanup_fb hook
1206 	 * set drm_gem_plane_helper_prepare_fb() is called automatically to
1207 	 * implement this. Other drivers which need additional plane processing
1208 	 * can call drm_gem_plane_helper_prepare_fb() from their @prepare_fb
1209 	 * hook.
1210 	 *
1211 	 * The resources acquired in @prepare_fb persist after the end of
1212 	 * the atomic commit. Resources that can be release at the commit's end
1213 	 * should be acquired in @begin_fb_access and released in @end_fb_access.
1214 	 * For example, a GEM buffer's pin operation belongs into @prepare_fb to
1215 	 * keep the buffer pinned after the commit. But a vmap operation for
1216 	 * shadow-plane helpers belongs into @begin_fb_access, so that atomic
1217 	 * helpers remove the mapping at the end of the commit.
1218 	 *
1219 	 * The helpers will call @cleanup_fb with matching arguments for every
1220 	 * successful call to this hook.
1221 	 *
1222 	 * This callback is used by the atomic modeset helpers, but it is
1223 	 * optional. See @begin_fb_access for preparing per-commit resources.
1224 	 *
1225 	 * RETURNS:
1226 	 *
1227 	 * 0 on success or one of the following negative error codes allowed by
1228 	 * the &drm_mode_config_funcs.atomic_commit vfunc. When using helpers
1229 	 * this callback is the only one which can fail an atomic commit,
1230 	 * everything else must complete successfully.
1231 	 */
1232 	int (*prepare_fb)(struct drm_plane *plane,
1233 			  struct drm_plane_state *new_state);
1234 	/**
1235 	 * @cleanup_fb:
1236 	 *
1237 	 * This hook is called to clean up any resources allocated for the given
1238 	 * framebuffer and plane configuration in @prepare_fb.
1239 	 *
1240 	 * This callback is used by the atomic modeset helpers, but it is
1241 	 * optional.
1242 	 */
1243 	void (*cleanup_fb)(struct drm_plane *plane,
1244 			   struct drm_plane_state *old_state);
1245 
1246 	/**
1247 	 * @begin_fb_access:
1248 	 *
1249 	 * This hook prepares the plane for access during an atomic commit.
1250 	 * In contrast to @prepare_fb, resources acquired in @begin_fb_access,
1251 	 * are released at the end of the atomic commit in @end_fb_access.
1252 	 *
1253 	 * For example, with shadow-plane helpers, the GEM buffer's vmap
1254 	 * operation belongs into @begin_fb_access, so that the buffer's
1255 	 * memory will be unmapped at the end of the commit in @end_fb_access.
1256 	 * But a GEM buffer's pin operation belongs into @prepare_fb
1257 	 * to keep the buffer pinned after the commit.
1258 	 *
1259 	 * The callback is used by the atomic modeset helpers, but it is optional.
1260 	 * See @end_fb_cleanup for undoing the effects of @begin_fb_access and
1261 	 * @prepare_fb for acquiring resources until the next pageflip.
1262 	 *
1263 	 * Returns:
1264 	 * 0 on success, or a negative errno code otherwise.
1265 	 */
1266 	int (*begin_fb_access)(struct drm_plane *plane, struct drm_plane_state *new_plane_state);
1267 
1268 	/**
1269 	 * @end_fb_access:
1270 	 *
1271 	 * This hook cleans up resources allocated by @begin_fb_access. It it called
1272 	 * at the end of a commit for the new plane state.
1273 	 */
1274 	void (*end_fb_access)(struct drm_plane *plane, struct drm_plane_state *new_plane_state);
1275 
1276 	/**
1277 	 * @atomic_check:
1278 	 *
1279 	 * Drivers should check plane specific constraints in this hook.
1280 	 *
1281 	 * When using drm_atomic_helper_check_planes() plane's @atomic_check
1282 	 * hooks are called before the ones for CRTCs, which allows drivers to
1283 	 * request shared resources that the CRTC controls here. For more
1284 	 * complicated dependencies the driver can call the provided check helpers
1285 	 * multiple times until the computed state has a final configuration and
1286 	 * everything has been checked.
1287 	 *
1288 	 * This function is also allowed to inspect any other object's state and
1289 	 * can add more state objects to the atomic commit if needed. Care must
1290 	 * be taken though to ensure that state check and compute functions for
1291 	 * these added states are all called, and derived state in other objects
1292 	 * all updated. Again the recommendation is to just call check helpers
1293 	 * until a maximal configuration is reached.
1294 	 *
1295 	 * This callback is used by the atomic modeset helpers, but it is
1296 	 * optional.
1297 	 *
1298 	 * NOTE:
1299 	 *
1300 	 * This function is called in the check phase of an atomic update. The
1301 	 * driver is not allowed to change anything outside of the
1302 	 * &drm_atomic_state update tracking structure.
1303 	 *
1304 	 * RETURNS:
1305 	 *
1306 	 * 0 on success, -EINVAL if the state or the transition can't be
1307 	 * supported, -ENOMEM on memory allocation failure and -EDEADLK if an
1308 	 * attempt to obtain another state object ran into a &drm_modeset_lock
1309 	 * deadlock.
1310 	 */
1311 	int (*atomic_check)(struct drm_plane *plane,
1312 			    struct drm_atomic_state *state);
1313 
1314 	/**
1315 	 * @atomic_update:
1316 	 *
1317 	 * Drivers should use this function to update the plane state.  This
1318 	 * hook is called in-between the &drm_crtc_helper_funcs.atomic_begin and
1319 	 * drm_crtc_helper_funcs.atomic_flush callbacks.
1320 	 *
1321 	 * Note that the power state of the display pipe when this function is
1322 	 * called depends upon the exact helpers and calling sequence the driver
1323 	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
1324 	 * the tradeoffs and variants of plane commit helpers.
1325 	 *
1326 	 * This callback is used by the atomic modeset helpers, but it is optional.
1327 	 */
1328 	void (*atomic_update)(struct drm_plane *plane,
1329 			      struct drm_atomic_state *state);
1330 
1331 	/**
1332 	 * @atomic_enable:
1333 	 *
1334 	 * Drivers should use this function to unconditionally enable a plane.
1335 	 * This hook is called in-between the &drm_crtc_helper_funcs.atomic_begin
1336 	 * and drm_crtc_helper_funcs.atomic_flush callbacks. It is called after
1337 	 * @atomic_update, which will be called for all enabled planes. Drivers
1338 	 * that use @atomic_enable should set up a plane in @atomic_update and
1339 	 * afterwards enable the plane in @atomic_enable. If a plane needs to be
1340 	 * enabled before installing the scanout buffer, drivers can still do
1341 	 * so in @atomic_update.
1342 	 *
1343 	 * Note that the power state of the display pipe when this function is
1344 	 * called depends upon the exact helpers and calling sequence the driver
1345 	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
1346 	 * the tradeoffs and variants of plane commit helpers.
1347 	 *
1348 	 * This callback is used by the atomic modeset helpers, but it is
1349 	 * optional. If implemented, @atomic_enable should be the inverse of
1350 	 * @atomic_disable. Drivers that don't want to use either can still
1351 	 * implement the complete plane update in @atomic_update.
1352 	 */
1353 	void (*atomic_enable)(struct drm_plane *plane,
1354 			      struct drm_atomic_state *state);
1355 
1356 	/**
1357 	 * @atomic_disable:
1358 	 *
1359 	 * Drivers should use this function to unconditionally disable a plane.
1360 	 * This hook is called in-between the
1361 	 * &drm_crtc_helper_funcs.atomic_begin and
1362 	 * drm_crtc_helper_funcs.atomic_flush callbacks. It is an alternative to
1363 	 * @atomic_update, which will be called for disabling planes, too, if
1364 	 * the @atomic_disable hook isn't implemented.
1365 	 *
1366 	 * This hook is also useful to disable planes in preparation of a modeset,
1367 	 * by calling drm_atomic_helper_disable_planes_on_crtc() from the
1368 	 * &drm_crtc_helper_funcs.disable hook.
1369 	 *
1370 	 * Note that the power state of the display pipe when this function is
1371 	 * called depends upon the exact helpers and calling sequence the driver
1372 	 * has picked. See drm_atomic_helper_commit_planes() for a discussion of
1373 	 * the tradeoffs and variants of plane commit helpers.
1374 	 *
1375 	 * This callback is used by the atomic modeset helpers, but it is
1376 	 * optional. It's intended to reverse the effects of @atomic_enable.
1377 	 */
1378 	void (*atomic_disable)(struct drm_plane *plane,
1379 			       struct drm_atomic_state *state);
1380 
1381 	/**
1382 	 * @atomic_async_check:
1383 	 *
1384 	 * Drivers should set this function pointer to check if the plane's
1385 	 * atomic state can be updated in a async fashion. Here async means
1386 	 * "not vblank synchronized".
1387 	 *
1388 	 * This hook is called by drm_atomic_async_check() to establish if a
1389 	 * given update can be committed asynchronously, that is, if it can
1390 	 * jump ahead of the state currently queued for update.
1391 	 *
1392 	 * RETURNS:
1393 	 *
1394 	 * Return 0 on success and any error returned indicates that the update
1395 	 * can not be applied in asynchronous manner.
1396 	 */
1397 	int (*atomic_async_check)(struct drm_plane *plane,
1398 				  struct drm_atomic_state *state);
1399 
1400 	/**
1401 	 * @atomic_async_update:
1402 	 *
1403 	 * Drivers should set this function pointer to perform asynchronous
1404 	 * updates of planes, that is, jump ahead of the currently queued
1405 	 * state and update the plane. Here async means "not vblank
1406 	 * synchronized".
1407 	 *
1408 	 * This hook is called by drm_atomic_helper_async_commit().
1409 	 *
1410 	 * An async update will happen on legacy cursor updates. An async
1411 	 * update won't happen if there is an outstanding commit modifying
1412 	 * the same plane.
1413 	 *
1414 	 * When doing async_update drivers shouldn't replace the
1415 	 * &drm_plane_state but update the current one with the new plane
1416 	 * configurations in the new plane_state.
1417 	 *
1418 	 * Drivers should also swap the framebuffers between current plane
1419 	 * state (&drm_plane.state) and new_state.
1420 	 * This is required since cleanup for async commits is performed on
1421 	 * the new state, rather than old state like for traditional commits.
1422 	 * Since we want to give up the reference on the current (old) fb
1423 	 * instead of our brand new one, swap them in the driver during the
1424 	 * async commit.
1425 	 *
1426 	 * FIXME:
1427 	 *  - It only works for single plane updates
1428 	 *  - Async Pageflips are not supported yet
1429 	 *  - Some hw might still scan out the old buffer until the next
1430 	 *    vblank, however we let go of the fb references as soon as
1431 	 *    we run this hook. For now drivers must implement their own workers
1432 	 *    for deferring if needed, until a common solution is created.
1433 	 */
1434 	void (*atomic_async_update)(struct drm_plane *plane,
1435 				    struct drm_atomic_state *state);
1436 };
1437 
1438 /**
1439  * drm_plane_helper_add - sets the helper vtable for a plane
1440  * @plane: DRM plane
1441  * @funcs: helper vtable to set for @plane
1442  */
1443 static inline void drm_plane_helper_add(struct drm_plane *plane,
1444 					const struct drm_plane_helper_funcs *funcs)
1445 {
1446 	plane->helper_private = funcs;
1447 }
1448 
1449 /**
1450  * struct drm_mode_config_helper_funcs - global modeset helper operations
1451  *
1452  * These helper functions are used by the atomic helpers.
1453  */
1454 struct drm_mode_config_helper_funcs {
1455 	/**
1456 	 * @atomic_commit_tail:
1457 	 *
1458 	 * This hook is used by the default atomic_commit() hook implemented in
1459 	 * drm_atomic_helper_commit() together with the nonblocking commit
1460 	 * helpers (see drm_atomic_helper_setup_commit() for a starting point)
1461 	 * to implement blocking and nonblocking commits easily. It is not used
1462 	 * by the atomic helpers
1463 	 *
1464 	 * This function is called when the new atomic state has already been
1465 	 * swapped into the various state pointers. The passed in state
1466 	 * therefore contains copies of the old/previous state. This hook should
1467 	 * commit the new state into hardware. Note that the helpers have
1468 	 * already waited for preceeding atomic commits and fences, but drivers
1469 	 * can add more waiting calls at the start of their implementation, e.g.
1470 	 * to wait for driver-internal request for implicit syncing, before
1471 	 * starting to commit the update to the hardware.
1472 	 *
1473 	 * After the atomic update is committed to the hardware this hook needs
1474 	 * to call drm_atomic_helper_commit_hw_done(). Then wait for the update
1475 	 * to be executed by the hardware, for example using
1476 	 * drm_atomic_helper_wait_for_vblanks() or
1477 	 * drm_atomic_helper_wait_for_flip_done(), and then clean up the old
1478 	 * framebuffers using drm_atomic_helper_cleanup_planes().
1479 	 *
1480 	 * When disabling a CRTC this hook _must_ stall for the commit to
1481 	 * complete. Vblank waits don't work on disabled CRTC, hence the core
1482 	 * can't take care of this. And it also can't rely on the vblank event,
1483 	 * since that can be signalled already when the screen shows black,
1484 	 * which can happen much earlier than the last hardware access needed to
1485 	 * shut off the display pipeline completely.
1486 	 *
1487 	 * This hook is optional, the default implementation is
1488 	 * drm_atomic_helper_commit_tail().
1489 	 */
1490 	void (*atomic_commit_tail)(struct drm_atomic_state *state);
1491 
1492 	/**
1493 	 * @atomic_commit_setup:
1494 	 *
1495 	 * This hook is used by the default atomic_commit() hook implemented in
1496 	 * drm_atomic_helper_commit() together with the nonblocking helpers (see
1497 	 * drm_atomic_helper_setup_commit()) to extend the DRM commit setup. It
1498 	 * is not used by the atomic helpers.
1499 	 *
1500 	 * This function is called at the end of
1501 	 * drm_atomic_helper_setup_commit(), so once the commit has been
1502 	 * properly setup across the generic DRM object states. It allows
1503 	 * drivers to do some additional commit tracking that isn't related to a
1504 	 * CRTC, plane or connector, tracked in a &drm_private_obj structure.
1505 	 *
1506 	 * Note that the documentation of &drm_private_obj has more details on
1507 	 * how one should implement this.
1508 	 *
1509 	 * This hook is optional.
1510 	 */
1511 	int (*atomic_commit_setup)(struct drm_atomic_state *state);
1512 };
1513 
1514 #endif
1515