summaryrefslogtreecommitdiffstats
path: root/drivers/gpu/drm/drm_framebuffer.c
blob: 588ccc3a22181b496cea4c6a43a5c16ccf8d48bb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
/*
 * Copyright (c) 2016 Intel Corporation
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that copyright
 * notice and this permission notice appear in supporting documentation, and
 * that the name of the copyright holders not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  The copyright holders make no representations
 * about the suitability of this software for any purpose.  It is provided "as
 * is" without express or implied warranty.
 *
 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 */

#include <linux/export.h>
#include <drm/drmP.h>
#include <drm/drm_auth.h>
#include <drm/drm_framebuffer.h>

#include "drm_crtc_internal.h"

/**
 * DOC: overview
 *
 * Frame buffers are abstract memory objects that provide a source of pixels to
 * scanout to a CRTC. Applications explicitly request the creation of frame
 * buffers through the DRM_IOCTL_MODE_ADDFB(2) ioctls and receive an opaque
 * handle that can be passed to the KMS CRTC control, plane configuration and
 * page flip functions.
 *
 * Frame buffers rely on the underlying memory manager for allocating backing
 * storage. When creating a frame buffer applications pass a memory handle
 * (or a list of memory handles for multi-planar formats) through the
 * &struct drm_mode_fb_cmd2 argument. For drivers using GEM as their userspace
 * buffer management interface this would be a GEM handle.  Drivers are however
 * free to use their own backing storage object handles, e.g. vmwgfx directly
 * exposes special TTM handles to userspace and so expects TTM handles in the
 * create ioctl and not GEM handles.
 *
 * Framebuffers are tracked with &struct drm_framebuffer. They are published
 * using drm_framebuffer_init() - after calling that function userspace can use
 * and access the framebuffer object. The helper function
 * drm_helper_mode_fill_fb_struct() can be used to pre-fill the required
 * metadata fields.
 *
 * The lifetime of a drm framebuffer is controlled with a reference count,
 * drivers can grab additional references with drm_framebuffer_reference() and
 * drop them again with drm_framebuffer_unreference(). For driver-private
 * framebuffers for which the last reference is never dropped (e.g. for the
 * fbdev framebuffer when the struct &struct drm_framebuffer is embedded into
 * the fbdev helper struct) drivers can manually clean up a framebuffer at
 * module unload time with drm_framebuffer_unregister_private(). But doing this
 * is not recommended, and it's better to have a normal free-standing struct
 * &drm_framebuffer.
 */

int drm_framebuffer_check_src_coords(uint32_t src_x, uint32_t src_y,
				     uint32_t src_w, uint32_t src_h,
				     const struct drm_framebuffer *fb)
{
	unsigned int fb_width, fb_height;

	fb_width = fb->width << 16;
	fb_height = fb->height << 16;

	/* Make sure source coordinates are inside the fb. */
	if (src_w > fb_width ||
	    src_x > fb_width - src_w ||
	    src_h > fb_height ||
	    src_y > fb_height - src_h) {
		DRM_DEBUG_KMS("Invalid source coordinates "
			      "%u.%06ux%u.%06u+%u.%06u+%u.%06u\n",
			      src_w >> 16, ((src_w & 0xffff) * 15625) >> 10,
			      src_h >> 16, ((src_h & 0xffff) * 15625) >> 10,
			      src_x >> 16, ((src_x & 0xffff) * 15625) >> 10,
			      src_y >> 16, ((src_y & 0xffff) * 15625) >> 10);
		return -ENOSPC;
	}

	return 0;
}

/**
 * drm_mode_addfb - add an FB to the graphics configuration
 * @dev: drm device for the ioctl
 * @data: data pointer for the ioctl
 * @file_priv: drm file for the ioctl call
 *
 * Add a new FB to the specified CRTC, given a user request. This is the
 * original addfb ioctl which only supported RGB formats.
 *
 * Called by the user via ioctl.
 *
 * Returns:
 * Zero on success, negative errno on failure.
 */
int drm_mode_addfb(struct drm_device *dev,
		   void *data, struct drm_file *file_priv)
{
	struct drm_mode_fb_cmd *or = data;
	struct drm_mode_fb_cmd2 r = {};
	int ret;

	/* convert to new format and call new ioctl */
	r.fb_id = or->fb_id;
	r.width = or->width;
	r.height = or->height;
	r.pitches[0] = or->pitch;
	r.pixel_format = drm_mode_legacy_fb_format(or->bpp, or->depth);
	r.handles[0] = or->handle;

	ret = drm_mode_addfb2(dev, &r, file_priv);
	if (ret)
		return ret;

	or->fb_id = r.fb_id;

	return 0;
}

static int framebuffer_check(const struct drm_mode_fb_cmd2 *r)
{
	const struct drm_format_info *info;
	int i;

	info = __drm_format_info(r->pixel_format & ~DRM_FORMAT_BIG_ENDIAN);
	if (!info) {
		struct drm_format_name_buf format_name;
		DRM_DEBUG_KMS("bad framebuffer format %s\n",
		              drm_get_format_name(r->pixel_format,
		                                  &format_name));
		return -EINVAL;
	}

	if (r->width == 0 || r->width % info->hsub) {
		DRM_DEBUG_KMS("bad framebuffer width %u\n", r->width);
		return -EINVAL;
	}

	if (r->height == 0 || r->height % info->vsub) {
		DRM_DEBUG_KMS("bad framebuffer height %u\n", r->height);
		return -EINVAL;
	}

	for (i = 0; i < info->num_planes; i++) {
		unsigned int width = r->width / (i != 0 ? info->hsub : 1);
		unsigned int height = r->height / (i != 0 ? info->vsub : 1);
		unsigned int cpp = info->cpp[i];

		if (!r->handles[i]) {
			DRM_DEBUG_KMS("no buffer object handle for plane %d\n", i);
			return -EINVAL;
		}

		if ((uint64_t) width * cpp > UINT_MAX)
			return -ERANGE;

		if ((uint64_t) height * r->pitches[i] + r->offsets[i] > UINT_MAX)
			return -ERANGE;

		if (r->pitches[i] < width * cpp) {
			DRM_DEBUG_KMS("bad pitch %u for plane %d\n", r->pitches[i], i);
			return -EINVAL;
		}

		if (r->modifier[i] && !(r->flags & DRM_MODE_FB_MODIFIERS)) {
			DRM_DEBUG_KMS("bad fb modifier %llu for plane %d\n",
				      r->modifier[i], i);
			return -EINVAL;
		}

		if (r->flags & DRM_MODE_FB_MODIFIERS &&
		    r->modifier[i] != r->modifier[0]) {
			DRM_DEBUG_KMS("bad fb modifier %llu for plane %d\n",
				      r->modifier[i], i);
			return -EINVAL;
		}

		/* modifier specific checks: */
		switch (r->modifier[i]) {
		case DRM_FORMAT_MOD_SAMSUNG_64_32_TILE:
			/* NOTE: the pitch restriction may be lifted later if it turns
			 * out that no hw has this restriction:
			 */
			if (r->pixel_format != DRM_FORMAT_NV12 ||
					width % 128 || height % 32 ||
					r->pitches[i] % 128) {
				DRM_DEBUG_KMS("bad modifier data for plane %d\n", i);
				return -EINVAL;
			}
			break;

		default:
			break;
		}
	}

	for (i = info->num_planes; i < 4; i++) {
		if (r->modifier[i]) {
			DRM_DEBUG_KMS("non-zero modifier for unused plane %d\n", i);
			return -EINVAL;
		}

		/* Pre-FB_MODIFIERS userspace didn't clear the structs properly. */
		if (!(r->flags & DRM_MODE_FB_MODIFIERS))
			continue;

		if (r->handles[i]) {
			DRM_DEBUG_KMS("buffer object handle for unused plane %d\n", i);
			return -EINVAL;
		}

		if (r->pitches[i]) {
			DRM_DEBUG_KMS("non-zero pitch for unused plane %d\n", i);
			return -EINVAL;
		}

		if (r->offsets[i]) {
			DRM_DEBUG_KMS("non-zero offset for unused plane %d\n", i);
			return -EINVAL;
		}
	}

	return 0;
}

struct drm_framebuffer *
drm_internal_framebuffer_create(struct drm_device *dev,
				const struct drm_mode_fb_cmd2 *r,
				struct drm_file *file_priv)
{
	struct drm_mode_config *config = &dev->mode_config;
	struct drm_framebuffer *fb;
	int ret;

	if (r->flags & ~(DRM_MODE_FB_INTERLACED | DRM_MODE_FB_MODIFIERS)) {
		DRM_DEBUG_KMS("bad framebuffer flags 0x%08x\n", r->flags);
		return ERR_PTR(-EINVAL);
	}

	if ((config->min_width > r->width) || (r->width > config->max_width)) {
		DRM_DEBUG_KMS("bad framebuffer width %d, should be >= %d && <= %d\n",
			  r->width, config->min_width, config->max_width);
		return ERR_PTR(-EINVAL);
	}
	if ((config->min_height > r->height) || (r->height > config->max_height)) {
		DRM_DEBUG_KMS("bad framebuffer height %d, should be >= %d && <= %d\n",
			  r->height, config->min_height, config->max_height);
		return ERR_PTR(-EINVAL);
	}

	if (r->flags & DRM_MODE_FB_MODIFIERS &&
	    !dev->mode_config.allow_fb_modifiers) {
		DRM_DEBUG_KMS("driver does not support fb modifiers\n");
		return ERR_PTR(-EINVAL);
	}

	ret = framebuffer_check(r);
	if (ret)
		return ERR_PTR(ret);

	fb = dev->mode_config.funcs->fb_create(dev, file_priv, r);
	if (IS_ERR(fb)) {
		DRM_DEBUG_KMS("could not create framebuffer\n");
		return fb;
	}

	return fb;
}

/**
 * drm_mode_addfb2 - add an FB to the graphics configuration
 * @dev: drm device for the ioctl
 * @data: data pointer for the ioctl
 * @file_priv: drm file for the ioctl call
 *
 * Add a new FB to the specified CRTC, given a user request with format. This is
 * the 2nd version of the addfb ioctl, which supports multi-planar framebuffers
 * and uses fourcc codes as pixel format specifiers.
 *
 * Called by the user via ioctl.
 *
 * Returns:
 * Zero on success, negative errno on failure.
 */
int drm_mode_addfb2(struct drm_device *dev,
		    void *data, struct drm_file *file_priv)
{
	struct drm_mode_fb_cmd2 *r = data;
	struct drm_framebuffer *fb;

	if (!drm_core_check_feature(dev, DRIVER_MODESET))
		return -EINVAL;

	fb = drm_internal_framebuffer_create(dev, r, file_priv);
	if (IS_ERR(fb))
		return PTR_ERR(fb);

	DRM_DEBUG_KMS("[FB:%d]\n", fb->base.id);
	r->fb_id = fb->base.id;

	/* Transfer ownership to the filp for reaping on close */
	mutex_lock(&file_priv->fbs_lock);
	list_add(&fb->filp_head, &file_priv->fbs);
	mutex_unlock(&file_priv->fbs_lock);

	return 0;
}

struct drm_mode_rmfb_work {
	struct work_struct work;
	struct list_head fbs;
};

static void drm_mode_rmfb_work_fn(struct work_struct *w)
{
	struct drm_mode_rmfb_work *arg = container_of(w, typeof(*arg), work);

	while (!list_empty(&arg->fbs)) {
		struct drm_framebuffer *fb =
			list_first_entry(&arg->fbs, typeof(*fb), filp_head);

		list_del_init(&fb->filp_head);
		drm_framebuffer_remove(fb);
	}
}

/**
 * drm_mode_rmfb - remove an FB from the configuration
 * @dev: drm device for the ioctl
 * @data: data pointer for the ioctl
 * @file_priv: drm file for the ioctl call
 *
 * Remove the FB specified by the user.
 *
 * Called by the user via ioctl.
 *
 * Returns:
 * Zero on success, negative errno on failure.
 */
int drm_mode_rmfb(struct drm_device *dev,
		   void *data, struct drm_file *file_priv)
{
	struct drm_framebuffer *fb = NULL;
	struct drm_framebuffer *fbl = NULL;
	uint32_t *id = data;
	int found = 0;

	if (!drm_core_check_feature(dev, DRIVER_MODESET))
		return -EINVAL;

	fb = drm_framebuffer_lookup(dev, *id);
	if (!fb)
		return -ENOENT;

	mutex_lock(&file_priv->fbs_lock);
	list_for_each_entry(fbl, &file_priv->fbs, filp_head)
		if (fb == fbl)
			found = 1;
	if (!found) {
		mutex_unlock(&file_priv->fbs_lock);
		goto fail_unref;
	}

	list_del_init(&fb->filp_head);
	mutex_unlock(&file_priv->fbs_lock);

	/* drop the reference we picked up in framebuffer lookup */
	drm_framebuffer_unreference(fb);

	/*
	 * we now own the reference that was stored in the fbs list
	 *
	 * drm_framebuffer_remove may fail with -EINTR on pending signals,
	 * so run this in a separate stack as there's no way to correctly
	 * handle this after the fb is already removed from the lookup table.
	 */
	if (drm_framebuffer_read_refcount(fb) > 1) {
		struct drm_mode_rmfb_work arg;

		INIT_WORK_ONSTACK(&arg.work, drm_mode_rmfb_work_fn);
		INIT_LIST_HEAD(&arg.fbs);
		list_add_tail(&fb->filp_head, &arg.fbs);

		schedule_work(&arg.work);
		flush_work(&arg.work);
		destroy_work_on_stack(&arg.work);
	} else
		drm_framebuffer_unreference(fb);

	return 0;

fail_unref:
	drm_framebuffer_unreference(fb);
	return -ENOENT;
}

/**
 * drm_mode_getfb - get FB info
 * @dev: drm device for the ioctl
 * @data: data pointer for the ioctl
 * @file_priv: drm file for the ioctl call
 *
 * Lookup the FB given its ID and return info about it.
 *
 * Called by the user via ioctl.
 *
 * Returns:
 * Zero on success, negative errno on failure.
 */
int drm_mode_getfb(struct drm_device *dev,
		   void *data, struct drm_file *file_priv)
{
	struct drm_mode_fb_cmd *r = data;
	struct drm_framebuffer *fb;
	int ret;

	if (!drm_core_check_feature(dev, DRIVER_MODESET))
		return -EINVAL;

	fb = drm_framebuffer_lookup(dev, r->fb_id);
	if (!fb)
		return -ENOENT;

	r->height = fb->height;
	r->width = fb->width;
	r->depth = fb->format->depth;
	r->bpp = fb->format->cpp[0] * 8;
	r->pitch = fb->pitches[0];
	if (fb->funcs->create_handle) {
		if (drm_is_current_master(file_priv) || capable(CAP_SYS_ADMIN) ||
		    drm_is_control_client(file_priv)) {
			ret = fb->funcs->create_handle(fb, file_priv,
						       &r->handle);
		} else {
			/* GET_FB() is an unprivileged ioctl so we must not
			 * return a buffer-handle to non-master processes! For
			 * backwards-compatibility reasons, we cannot make
			 * GET_FB() privileged, so just return an invalid handle
			 * for non-masters. */
			r->handle = 0;
			ret = 0;
		}
	} else {
		ret = -ENODEV;
	}

	drm_framebuffer_unreference(fb);

	return ret;
}

/**
 * drm_mode_dirtyfb_ioctl - flush frontbuffer rendering on an FB
 * @dev: drm device for the ioctl
 * @data: data pointer for the ioctl
 * @file_priv: drm file for the ioctl call
 *
 * Lookup the FB and flush out the damaged area supplied by userspace as a clip
 * rectangle list. Generic userspace which does frontbuffer rendering must call
 * this ioctl to flush out the changes on manual-update display outputs, e.g.
 * usb display-link, mipi manual update panels or edp panel self refresh modes.
 *
 * Modesetting drivers which always update the frontbuffer do not need to
 * implement the corresponding ->dirty framebuffer callback.
 *
 * Called by the user via ioctl.
 *
 * Returns:
 * Zero on success, negative errno on failure.
 */
int drm_mode_dirtyfb_ioctl(struct drm_device *dev,
			   void *data, struct drm_file *file_priv)
{
	struct drm_clip_rect __user *clips_ptr;
	struct drm_clip_rect *clips = NULL;
	struct drm_mode_fb_dirty_cmd *r = data;
	struct drm_framebuffer *fb;
	unsigned flags;
	int num_clips;
	int ret;

	if (!drm_core_check_feature(dev, DRIVER_MODESET))
		return -EINVAL;

	fb = drm_framebuffer_lookup(dev, r->fb_id);
	if (!fb)
		return -ENOENT;

	num_clips = r->num_clips;
	clips_ptr = (struct drm_clip_rect __user *)(unsigned long)r->clips_ptr;

	if (!num_clips != !clips_ptr) {
		ret = -EINVAL;
		goto out_err1;
	}

	flags = DRM_MODE_FB_DIRTY_FLAGS & r->flags;

	/* If userspace annotates copy, clips must come in pairs */
	if (flags & DRM_MODE_FB_DIRTY_ANNOTATE_COPY && (num_clips % 2)) {
		ret = -EINVAL;
		goto out_err1;
	}

	if (num_clips && clips_ptr) {
		if (num_clips < 0 || num_clips > DRM_MODE_FB_DIRTY_MAX_CLIPS) {
			ret = -EINVAL;
			goto out_err1;
		}
		clips = kcalloc(num_clips, sizeof(*clips), GFP_KERNEL);
		if (!clips) {
			ret = -ENOMEM;
			goto out_err1;
		}

		ret = copy_from_user(clips, clips_ptr,
				     num_clips * sizeof(*clips));
		if (ret) {
			ret = -EFAULT;
			goto out_err2;
		}
	}

	if (fb->funcs->dirty) {
		ret = fb->funcs->dirty(fb, file_priv, flags, r->color,
				       clips, num_clips);
	} else {
		ret = -ENOSYS;
	}

out_err2:
	kfree(clips);
out_err1:
	drm_framebuffer_unreference(fb);

	return ret;
}

/**
 * drm_fb_release - remove and free the FBs on this file
 * @priv: drm file for the ioctl
 *
 * Destroy all the FBs associated with @filp.
 *
 * Called by the user via ioctl.
 *
 * Returns:
 * Zero on success, negative errno on failure.
 */
void drm_fb_release(struct drm_file *priv)
{
	struct drm_framebuffer *fb, *tfb;
	struct drm_mode_rmfb_work arg;

	INIT_LIST_HEAD(&arg.fbs);

	/*
	 * When the file gets released that means no one else can access the fb
	 * list any more, so no need to grab fpriv->fbs_lock. And we need to
	 * avoid upsetting lockdep since the universal cursor code adds a
	 * framebuffer while holding mutex locks.
	 *
	 * Note that a real deadlock between fpriv->fbs_lock and the modeset
	 * locks is impossible here since no one else but this function can get
	 * at it any more.
	 */
	list_for_each_entry_safe(fb, tfb, &priv->fbs, filp_head) {
		if (drm_framebuffer_read_refcount(fb) > 1) {
			list_move_tail(&fb->filp_head, &arg.fbs);
		} else {
			list_del_init(&fb->filp_head);

			/* This drops the fpriv->fbs reference. */
			drm_framebuffer_unreference(fb);
		}
	}

	if (!list_empty(&arg.fbs)) {
		INIT_WORK_ONSTACK(&arg.work, drm_mode_rmfb_work_fn);

		schedule_work(&arg.work);
		flush_work(&arg.work);
		destroy_work_on_stack(&arg.work);
	}
}

void drm_framebuffer_free(struct kref *kref)
{
	struct drm_framebuffer *fb =
			container_of(kref, struct drm_framebuffer, base.refcount);
	struct drm_device *dev = fb->dev;

	/*
	 * The lookup idr holds a weak reference, which has not necessarily been
	 * removed at this point. Check for that.
	 */
	drm_mode_object_unregister(dev, &fb->base);

	fb->funcs->destroy(fb);
}

/**
 * drm_framebuffer_init - initialize a framebuffer
 * @dev: DRM device
 * @fb: framebuffer to be initialized
 * @funcs: ... with these functions
 *
 * Allocates an ID for the framebuffer's parent mode object, sets its mode
 * functions & device file and adds it to the master fd list.
 *
 * IMPORTANT:
 * This functions publishes the fb and makes it available for concurrent access
 * by other users. Which means by this point the fb _must_ be fully set up -
 * since all the fb attributes are invariant over its lifetime, no further
 * locking but only correct reference counting is required.
 *
 * Returns:
 * Zero on success, error code on failure.
 */
int drm_framebuffer_init(struct drm_device *dev, struct drm_framebuffer *fb,
			 const struct drm_framebuffer_funcs *funcs)
{
	int ret;

	if (WARN_ON_ONCE(fb->dev != dev || !fb->format))
		return -EINVAL;

	INIT_LIST_HEAD(&fb->filp_head);

	fb->funcs = funcs;

	ret = drm_mode_object_get_reg(dev, &fb->base, DRM_MODE_OBJECT_FB,
				      false, drm_framebuffer_free);
	if (ret)
		goto out;

	mutex_lock(&dev->mode_config.fb_lock);
	dev->mode_config.num_fb++;
	list_add(&fb->head, &dev->mode_config.fb_list);
	mutex_unlock(&dev->mode_config.fb_lock);

	drm_mode_object_register(dev, &fb->base);
out:
	return ret;
}
EXPORT_SYMBOL(drm_framebuffer_init);

/**
 * drm_framebuffer_lookup - look up a drm framebuffer and grab a reference
 * @dev: drm device
 * @id: id of the fb object
 *
 * If successful, this grabs an additional reference to the framebuffer -
 * callers need to make sure to eventually unreference the returned framebuffer
 * again, using @drm_framebuffer_unreference.
 */
struct drm_framebuffer *drm_framebuffer_lookup(struct drm_device *dev,
					       uint32_t id)
{
	struct drm_mode_object *obj;
	struct drm_framebuffer *fb = NULL;

	obj = __drm_mode_object_find(dev, id, DRM_MODE_OBJECT_FB);
	if (obj)
		fb = obj_to_fb(obj);
	return fb;
}
EXPORT_SYMBOL(drm_framebuffer_lookup);

/**
 * drm_framebuffer_unregister_private - unregister a private fb from the lookup idr
 * @fb: fb to unregister
 *
 * Drivers need to call this when cleaning up driver-private framebuffers, e.g.
 * those used for fbdev. Note that the caller must hold a reference of it's own,
 * i.e. the object may not be destroyed through this call (since it'll lead to a
 * locking inversion).
 *
 * NOTE: This function is deprecated. For driver-private framebuffers it is not
 * recommended to embed a framebuffer struct info fbdev struct, instead, a
 * framebuffer pointer is preferred and drm_framebuffer_unreference() should be
 * called when the framebuffer is to be cleaned up.
 */
void drm_framebuffer_unregister_private(struct drm_framebuffer *fb)
{
	struct drm_device *dev;

	if (!fb)
		return;

	dev = fb->dev;

	/* Mark fb as reaped and drop idr ref. */
	drm_mode_object_unregister(dev, &fb->base);
}
EXPORT_SYMBOL(drm_framebuffer_unregister_private);

/**
 * drm_framebuffer_cleanup - remove a framebuffer object
 * @fb: framebuffer to remove
 *
 * Cleanup framebuffer. This function is intended to be used from the drivers
 * ->destroy callback. It can also be used to clean up driver private
 * framebuffers embedded into a larger structure.
 *
 * Note that this function does not remove the fb from active usuage - if it is
 * still used anywhere, hilarity can ensue since userspace could call getfb on
 * the id and get back -EINVAL. Obviously no concern at driver unload time.
 *
 * Also, the framebuffer will not be removed from the lookup idr - for
 * user-created framebuffers this will happen in in the rmfb ioctl. For
 * driver-private objects (e.g. for fbdev) drivers need to explicitly call
 * drm_framebuffer_unregister_private.
 */
void drm_framebuffer_cleanup(struct drm_framebuffer *fb)
{
	struct drm_device *dev = fb->dev;

	mutex_lock(&dev->mode_config.fb_lock);
	list_del(&fb->head);
	dev->mode_config.num_fb--;
	mutex_unlock(&dev->mode_config.fb_lock);
}
EXPORT_SYMBOL(drm_framebuffer_cleanup);

/**
 * drm_framebuffer_remove - remove and unreference a framebuffer object
 * @fb: framebuffer to remove
 *
 * Scans all the CRTCs and planes in @dev's mode_config.  If they're
 * using @fb, removes it, setting it to NULL. Then drops the reference to the
 * passed-in framebuffer. Might take the modeset locks.
 *
 * Note that this function optimizes the cleanup away if the caller holds the
 * last reference to the framebuffer. It is also guaranteed to not take the
 * modeset locks in this case.
 */
void drm_framebuffer_remove(struct drm_framebuffer *fb)
{
	struct drm_device *dev;
	struct drm_crtc *crtc;
	struct drm_plane *plane;

	if (!fb)
		return;

	dev = fb->dev;

	WARN_ON(!list_empty(&fb->filp_head));

	/*
	 * drm ABI mandates that we remove any deleted framebuffers from active
	 * useage. But since most sane clients only remove framebuffers they no
	 * longer need, try to optimize this away.
	 *
	 * Since we're holding a reference ourselves, observing a refcount of 1
	 * means that we're the last holder and can skip it. Also, the refcount
	 * can never increase from 1 again, so we don't need any barriers or
	 * locks.
	 *
	 * Note that userspace could try to race with use and instate a new
	 * usage _after_ we've cleared all current ones. End result will be an
	 * in-use fb with fb-id == 0. Userspace is allowed to shoot its own foot
	 * in this manner.
	 */
	if (drm_framebuffer_read_refcount(fb) > 1) {
		drm_modeset_lock_all(dev);
		/* remove from any CRTC */
		drm_for_each_crtc(crtc, dev) {
			if (crtc->primary->fb == fb) {
				/* should turn off the crtc */
				if (drm_crtc_force_disable(crtc))
					DRM_ERROR("failed to reset crtc %p when fb was deleted\n", crtc);
			}
		}

		drm_for_each_plane(plane, dev) {
			if (plane->fb == fb)
				drm_plane_force_disable(plane);
		}
		drm_modeset_unlock_all(dev);
	}

	drm_framebuffer_unreference(fb);
}
EXPORT_SYMBOL(drm_framebuffer_remove);

/**
 * drm_framebuffer_plane_width - width of the plane given the first plane
 * @width: width of the first plane
 * @fb: the framebuffer
 * @plane: plane index
 *
 * Returns:
 * The width of @plane, given that the width of the first plane is @width.
 */
int drm_framebuffer_plane_width(int width,
				const struct drm_framebuffer *fb, int plane)
{
	if (plane >= fb->format->num_planes)
		return 0;

	if (plane == 0)
		return width;

	return width / fb->format->hsub;
}
EXPORT_SYMBOL(drm_framebuffer_plane_width);

/**
 * drm_framebuffer_plane_height - height of the plane given the first plane
 * @height: height of the first plane
 * @fb: the framebuffer
 * @plane: plane index
 *
 * Returns:
 * The height of @plane, given that the height of the first plane is @height.
 */
int drm_framebuffer_plane_height(int height,
				 const struct drm_framebuffer *fb, int plane)
{
	if (plane >= fb->format->num_planes)
		return 0;

	if (plane == 0)
		return height;

	return height / fb->format->vsub;
}
EXPORT_SYMBOL(drm_framebuffer_plane_height);