1 /*
2  * Copyright (C) 2016 Samsung Electronics Co.Ltd
3  * Authors:
4  *	Marek Szyprowski <m.szyprowski@samsung.com>
5  *
6  * DRM core plane blending related functions
7  *
8  * Permission to use, copy, modify, distribute, and sell this software and its
9  * documentation for any purpose is hereby granted without fee, provided that
10  * the above copyright notice appear in all copies and that both that copyright
11  * notice and this permission notice appear in supporting documentation, and
12  * that the name of the copyright holders not be used in advertising or
13  * publicity pertaining to distribution of the software without specific,
14  * written prior permission.  The copyright holders make no representations
15  * about the suitability of this software for any purpose.  It is provided "as
16  * is" without express or implied warranty.
17  *
18  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
19  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
20  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
21  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
22  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
23  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
24  * OF THIS SOFTWARE.
25  */
26 
27 #include <linux/export.h>
28 #include <linux/slab.h>
29 #include <linux/sort.h>
30 
31 #include <drm/drm_atomic.h>
32 #include <drm/drm_blend.h>
33 #include <drm/drm_device.h>
34 #include <drm/drm_print.h>
35 
36 #include "drm_crtc_internal.h"
37 
38 /**
39  * DOC: overview
40  *
41  * The basic plane composition model supported by standard plane properties only
42  * has a source rectangle (in logical pixels within the &drm_framebuffer), with
43  * sub-pixel accuracy, which is scaled up to a pixel-aligned destination
44  * rectangle in the visible area of a &drm_crtc. The visible area of a CRTC is
45  * defined by the horizontal and vertical visible pixels (stored in @hdisplay
46  * and @vdisplay) of the requested mode (stored in &drm_crtc_state.mode). These
47  * two rectangles are both stored in the &drm_plane_state.
48  *
49  * For the atomic ioctl the following standard (atomic) properties on the plane object
50  * encode the basic plane composition model:
51  *
52  * SRC_X:
53  * 	X coordinate offset for the source rectangle within the
54  * 	&drm_framebuffer, in 16.16 fixed point. Must be positive.
55  * SRC_Y:
56  * 	Y coordinate offset for the source rectangle within the
57  * 	&drm_framebuffer, in 16.16 fixed point. Must be positive.
58  * SRC_W:
59  * 	Width for the source rectangle within the &drm_framebuffer, in 16.16
60  * 	fixed point. SRC_X plus SRC_W must be within the width of the source
61  * 	framebuffer. Must be positive.
62  * SRC_H:
63  * 	Height for the source rectangle within the &drm_framebuffer, in 16.16
64  * 	fixed point. SRC_Y plus SRC_H must be within the height of the source
65  * 	framebuffer. Must be positive.
66  * CRTC_X:
67  * 	X coordinate offset for the destination rectangle. Can be negative.
68  * CRTC_Y:
69  * 	Y coordinate offset for the destination rectangle. Can be negative.
70  * CRTC_W:
71  * 	Width for the destination rectangle. CRTC_X plus CRTC_W can extend past
72  * 	the currently visible horizontal area of the &drm_crtc.
73  * CRTC_H:
74  * 	Height for the destination rectangle. CRTC_Y plus CRTC_H can extend past
75  * 	the currently visible vertical area of the &drm_crtc.
76  * FB_ID:
77  * 	Mode object ID of the &drm_framebuffer this plane should scan out.
78  * CRTC_ID:
79  * 	Mode object ID of the &drm_crtc this plane should be connected to.
80  *
81  * Note that the source rectangle must fully lie within the bounds of the
82  * &drm_framebuffer. The destination rectangle can lie outside of the visible
83  * area of the current mode of the CRTC. It must be appropriately clipped by the
84  * driver, which can be done by calling drm_plane_helper_check_update(). Drivers
85  * are also allowed to round the subpixel sampling positions appropriately, but
86  * only to the next full pixel. No pixel outside of the source rectangle may
87  * ever be sampled, which is important when applying more sophisticated
88  * filtering than just a bilinear one when scaling. The filtering mode when
89  * scaling is unspecified.
90  *
91  * On top of this basic transformation additional properties can be exposed by
92  * the driver:
93  *
94  * alpha:
95  * 	Alpha is setup with drm_plane_create_alpha_property(). It controls the
96  * 	plane-wide opacity, from transparent (0) to opaque (0xffff). It can be
97  * 	combined with pixel alpha.
98  *	The pixel values in the framebuffers are expected to not be
99  *	pre-multiplied by the global alpha associated to the plane.
100  *
101  * rotation:
102  *	Rotation is set up with drm_plane_create_rotation_property(). It adds a
103  *	rotation and reflection step between the source and destination rectangles.
104  *	Without this property the rectangle is only scaled, but not rotated or
105  *	reflected.
106  *
107  *	Possbile values:
108  *
109  *	"rotate-<degrees>":
110  *		Signals that a drm plane is rotated <degrees> degrees in counter
111  *		clockwise direction.
112  *
113  *	"reflect-<axis>":
114  *		Signals that the contents of a drm plane is reflected along the
115  *		<axis> axis, in the same way as mirroring.
116  *
117  *	reflect-x::
118  *
119  *			|o |    | o|
120  *			|  | -> |  |
121  *			| v|    |v |
122  *
123  *	reflect-y::
124  *
125  *			|o |    | ^|
126  *			|  | -> |  |
127  *			| v|    |o |
128  *
129  * zpos:
130  *	Z position is set up with drm_plane_create_zpos_immutable_property() and
131  *	drm_plane_create_zpos_property(). It controls the visibility of overlapping
132  *	planes. Without this property the primary plane is always below the cursor
133  *	plane, and ordering between all other planes is undefined. The positive
134  *	Z axis points towards the user, i.e. planes with lower Z position values
135  *	are underneath planes with higher Z position values. Two planes with the
136  *	same Z position value have undefined ordering. Note that the Z position
137  *	value can also be immutable, to inform userspace about the hard-coded
138  *	stacking of planes, see drm_plane_create_zpos_immutable_property(). If
139  *	any plane has a zpos property (either mutable or immutable), then all
140  *	planes shall have a zpos property.
141  *
142  * pixel blend mode:
143  *	Pixel blend mode is set up with drm_plane_create_blend_mode_property().
144  *	It adds a blend mode for alpha blending equation selection, describing
145  *	how the pixels from the current plane are composited with the
146  *	background.
147  *
148  *	 Three alpha blending equations are defined:
149  *
150  *	 "None":
151  *		 Blend formula that ignores the pixel alpha::
152  *
153  *			 out.rgb = plane_alpha * fg.rgb +
154  *				 (1 - plane_alpha) * bg.rgb
155  *
156  *	 "Pre-multiplied":
157  *		 Blend formula that assumes the pixel color values
158  *		 have been already pre-multiplied with the alpha
159  *		 channel values::
160  *
161  *			 out.rgb = plane_alpha * fg.rgb +
162  *				 (1 - (plane_alpha * fg.alpha)) * bg.rgb
163  *
164  *	 "Coverage":
165  *		 Blend formula that assumes the pixel color values have not
166  *		 been pre-multiplied and will do so when blending them to the
167  *		 background color values::
168  *
169  *			 out.rgb = plane_alpha * fg.alpha * fg.rgb +
170  *				 (1 - (plane_alpha * fg.alpha)) * bg.rgb
171  *
172  *	 Using the following symbols:
173  *
174  *	 "fg.rgb":
175  *		 Each of the RGB component values from the plane's pixel
176  *	 "fg.alpha":
177  *		 Alpha component value from the plane's pixel. If the plane's
178  *		 pixel format has no alpha component, then this is assumed to be
179  *		 1.0. In these cases, this property has no effect, as all three
180  *		 equations become equivalent.
181  *	 "bg.rgb":
182  *		 Each of the RGB component values from the background
183  *	 "plane_alpha":
184  *		 Plane alpha value set by the plane "alpha" property. If the
185  *		 plane does not expose the "alpha" property, then this is
186  *		 assumed to be 1.0
187  *
188  * Note that all the property extensions described here apply either to the
189  * plane or the CRTC (e.g. for the background color, which currently is not
190  * exposed and assumed to be black).
191  *
192  * SCALING_FILTER:
193  *     Indicates scaling filter to be used for plane scaler
194  *
195  *     The value of this property can be one of the following:
196  *
197  *     Default:
198  *             Driver's default scaling filter
199  *     Nearest Neighbor:
200  *             Nearest Neighbor scaling filter
201  *
202  * Drivers can set up this property for a plane by calling
203  * drm_plane_create_scaling_filter_property
204  */
205 
206 /**
207  * drm_plane_create_alpha_property - create a new alpha property
208  * @plane: drm plane
209  *
210  * This function creates a generic, mutable, alpha property and enables support
211  * for it in the DRM core. It is attached to @plane.
212  *
213  * The alpha property will be allowed to be within the bounds of 0
214  * (transparent) to 0xffff (opaque).
215  *
216  * Returns:
217  * 0 on success, negative error code on failure.
218  */
drm_plane_create_alpha_property(struct drm_plane * plane)219 int drm_plane_create_alpha_property(struct drm_plane *plane)
220 {
221 	struct drm_property *prop;
222 
223 	prop = drm_property_create_range(plane->dev, 0, "alpha",
224 					 0, DRM_BLEND_ALPHA_OPAQUE);
225 	if (!prop)
226 		return -ENOMEM;
227 
228 	drm_object_attach_property(&plane->base, prop, DRM_BLEND_ALPHA_OPAQUE);
229 	plane->alpha_property = prop;
230 
231 	if (plane->state)
232 		plane->state->alpha = DRM_BLEND_ALPHA_OPAQUE;
233 
234 	return 0;
235 }
236 EXPORT_SYMBOL(drm_plane_create_alpha_property);
237 
238 /**
239  * drm_plane_create_rotation_property - create a new rotation property
240  * @plane: drm plane
241  * @rotation: initial value of the rotation property
242  * @supported_rotations: bitmask of supported rotations and reflections
243  *
244  * This creates a new property with the selected support for transformations.
245  *
246  * Since a rotation by 180° degress is the same as reflecting both along the x
247  * and the y axis the rotation property is somewhat redundant. Drivers can use
248  * drm_rotation_simplify() to normalize values of this property.
249  *
250  * The property exposed to userspace is a bitmask property (see
251  * drm_property_create_bitmask()) called "rotation" and has the following
252  * bitmask enumaration values:
253  *
254  * DRM_MODE_ROTATE_0:
255  * 	"rotate-0"
256  * DRM_MODE_ROTATE_90:
257  * 	"rotate-90"
258  * DRM_MODE_ROTATE_180:
259  * 	"rotate-180"
260  * DRM_MODE_ROTATE_270:
261  * 	"rotate-270"
262  * DRM_MODE_REFLECT_X:
263  * 	"reflect-x"
264  * DRM_MODE_REFLECT_Y:
265  * 	"reflect-y"
266  *
267  * Rotation is the specified amount in degrees in counter clockwise direction,
268  * the X and Y axis are within the source rectangle, i.e.  the X/Y axis before
269  * rotation. After reflection, the rotation is applied to the image sampled from
270  * the source rectangle, before scaling it to fit the destination rectangle.
271  */
drm_plane_create_rotation_property(struct drm_plane * plane,unsigned int rotation,unsigned int supported_rotations)272 int drm_plane_create_rotation_property(struct drm_plane *plane,
273 				       unsigned int rotation,
274 				       unsigned int supported_rotations)
275 {
276 	static const struct drm_prop_enum_list props[] = {
277 		{ __builtin_ffs(DRM_MODE_ROTATE_0) - 1,   "rotate-0" },
278 		{ __builtin_ffs(DRM_MODE_ROTATE_90) - 1,  "rotate-90" },
279 		{ __builtin_ffs(DRM_MODE_ROTATE_180) - 1, "rotate-180" },
280 		{ __builtin_ffs(DRM_MODE_ROTATE_270) - 1, "rotate-270" },
281 		{ __builtin_ffs(DRM_MODE_REFLECT_X) - 1,  "reflect-x" },
282 		{ __builtin_ffs(DRM_MODE_REFLECT_Y) - 1,  "reflect-y" },
283 	};
284 	struct drm_property *prop;
285 
286 	WARN_ON((supported_rotations & DRM_MODE_ROTATE_MASK) == 0);
287 	WARN_ON(!is_power_of_2(rotation & DRM_MODE_ROTATE_MASK));
288 	WARN_ON(rotation & ~supported_rotations);
289 
290 	prop = drm_property_create_bitmask(plane->dev, 0, "rotation",
291 					   props, ARRAY_SIZE(props),
292 					   supported_rotations);
293 	if (!prop)
294 		return -ENOMEM;
295 
296 	drm_object_attach_property(&plane->base, prop, rotation);
297 
298 	if (plane->state)
299 		plane->state->rotation = rotation;
300 
301 	plane->rotation_property = prop;
302 
303 	return 0;
304 }
305 EXPORT_SYMBOL(drm_plane_create_rotation_property);
306 
307 /**
308  * drm_rotation_simplify() - Try to simplify the rotation
309  * @rotation: Rotation to be simplified
310  * @supported_rotations: Supported rotations
311  *
312  * Attempt to simplify the rotation to a form that is supported.
313  * Eg. if the hardware supports everything except DRM_MODE_REFLECT_X
314  * one could call this function like this:
315  *
316  * drm_rotation_simplify(rotation, DRM_MODE_ROTATE_0 |
317  *                       DRM_MODE_ROTATE_90 | DRM_MODE_ROTATE_180 |
318  *                       DRM_MODE_ROTATE_270 | DRM_MODE_REFLECT_Y);
319  *
320  * to eliminate the DRM_MODE_REFLECT_X flag. Depending on what kind of
321  * transforms the hardware supports, this function may not
322  * be able to produce a supported transform, so the caller should
323  * check the result afterwards.
324  */
drm_rotation_simplify(unsigned int rotation,unsigned int supported_rotations)325 unsigned int drm_rotation_simplify(unsigned int rotation,
326 				   unsigned int supported_rotations)
327 {
328 	if (rotation & ~supported_rotations) {
329 		rotation ^= DRM_MODE_REFLECT_X | DRM_MODE_REFLECT_Y;
330 		rotation = (rotation & DRM_MODE_REFLECT_MASK) |
331 			    BIT((ffs(rotation & DRM_MODE_ROTATE_MASK) + 1)
332 			    % 4);
333 	}
334 
335 	return rotation;
336 }
337 EXPORT_SYMBOL(drm_rotation_simplify);
338 
339 /**
340  * drm_plane_create_zpos_property - create mutable zpos property
341  * @plane: drm plane
342  * @zpos: initial value of zpos property
343  * @min: minimal possible value of zpos property
344  * @max: maximal possible value of zpos property
345  *
346  * This function initializes generic mutable zpos property and enables support
347  * for it in drm core. Drivers can then attach this property to planes to enable
348  * support for configurable planes arrangement during blending operation.
349  * Drivers that attach a mutable zpos property to any plane should call the
350  * drm_atomic_normalize_zpos() helper during their implementation of
351  * &drm_mode_config_funcs.atomic_check(), which will update the normalized zpos
352  * values and store them in &drm_plane_state.normalized_zpos. Usually min
353  * should be set to 0 and max to maximal number of planes for given crtc - 1.
354  *
355  * If zpos of some planes cannot be changed (like fixed background or
356  * cursor/topmost planes), drivers shall adjust the min/max values and assign
357  * those planes immutable zpos properties with lower or higher values (for more
358  * information, see drm_plane_create_zpos_immutable_property() function). In such
359  * case drivers shall also assign proper initial zpos values for all planes in
360  * its plane_reset() callback, so the planes will be always sorted properly.
361  *
362  * See also drm_atomic_normalize_zpos().
363  *
364  * The property exposed to userspace is called "zpos".
365  *
366  * Returns:
367  * Zero on success, negative errno on failure.
368  */
drm_plane_create_zpos_property(struct drm_plane * plane,unsigned int zpos,unsigned int min,unsigned int max)369 int drm_plane_create_zpos_property(struct drm_plane *plane,
370 				   unsigned int zpos,
371 				   unsigned int min, unsigned int max)
372 {
373 	struct drm_property *prop;
374 
375 	prop = drm_property_create_range(plane->dev, 0, "zpos", min, max);
376 	if (!prop)
377 		return -ENOMEM;
378 
379 	drm_object_attach_property(&plane->base, prop, zpos);
380 
381 	plane->zpos_property = prop;
382 
383 	if (plane->state) {
384 		plane->state->zpos = zpos;
385 		plane->state->normalized_zpos = zpos;
386 	}
387 
388 	return 0;
389 }
390 EXPORT_SYMBOL(drm_plane_create_zpos_property);
391 
392 /**
393  * drm_plane_create_zpos_immutable_property - create immuttable zpos property
394  * @plane: drm plane
395  * @zpos: value of zpos property
396  *
397  * This function initializes generic immutable zpos property and enables
398  * support for it in drm core. Using this property driver lets userspace
399  * to get the arrangement of the planes for blending operation and notifies
400  * it that the hardware (or driver) doesn't support changing of the planes'
401  * order. For mutable zpos see drm_plane_create_zpos_property().
402  *
403  * The property exposed to userspace is called "zpos".
404  *
405  * Returns:
406  * Zero on success, negative errno on failure.
407  */
drm_plane_create_zpos_immutable_property(struct drm_plane * plane,unsigned int zpos)408 int drm_plane_create_zpos_immutable_property(struct drm_plane *plane,
409 					     unsigned int zpos)
410 {
411 	struct drm_property *prop;
412 
413 	prop = drm_property_create_range(plane->dev, DRM_MODE_PROP_IMMUTABLE,
414 					 "zpos", zpos, zpos);
415 	if (!prop)
416 		return -ENOMEM;
417 
418 	drm_object_attach_property(&plane->base, prop, zpos);
419 
420 	plane->zpos_property = prop;
421 
422 	if (plane->state) {
423 		plane->state->zpos = zpos;
424 		plane->state->normalized_zpos = zpos;
425 	}
426 
427 	return 0;
428 }
429 EXPORT_SYMBOL(drm_plane_create_zpos_immutable_property);
430 
drm_atomic_state_zpos_cmp(const void * a,const void * b)431 static int drm_atomic_state_zpos_cmp(const void *a, const void *b)
432 {
433 	const struct drm_plane_state *sa = *(struct drm_plane_state **)a;
434 	const struct drm_plane_state *sb = *(struct drm_plane_state **)b;
435 
436 	if (sa->zpos != sb->zpos)
437 		return sa->zpos - sb->zpos;
438 	else
439 		return sa->plane->base.id - sb->plane->base.id;
440 }
441 
drm_atomic_helper_crtc_normalize_zpos(struct drm_crtc * crtc,struct drm_crtc_state * crtc_state)442 static int drm_atomic_helper_crtc_normalize_zpos(struct drm_crtc *crtc,
443 					  struct drm_crtc_state *crtc_state)
444 {
445 	struct drm_atomic_state *state = crtc_state->state;
446 	struct drm_device *dev = crtc->dev;
447 	int total_planes = dev->mode_config.num_total_plane;
448 	struct drm_plane_state **states;
449 	struct drm_plane *plane;
450 	int i, n = 0;
451 	int ret = 0;
452 
453 	drm_dbg_atomic(dev, "[CRTC:%d:%s] calculating normalized zpos values\n",
454 		       crtc->base.id, crtc->name);
455 
456 	states = kmalloc_array(total_planes, sizeof(*states), GFP_KERNEL);
457 	if (!states)
458 		return -ENOMEM;
459 
460 	/*
461 	 * Normalization process might create new states for planes which
462 	 * normalized_zpos has to be recalculated.
463 	 */
464 	drm_for_each_plane_mask(plane, dev, crtc_state->plane_mask) {
465 		struct drm_plane_state *plane_state =
466 			drm_atomic_get_plane_state(state, plane);
467 		if (IS_ERR(plane_state)) {
468 			ret = PTR_ERR(plane_state);
469 			goto done;
470 		}
471 		states[n++] = plane_state;
472 		drm_dbg_atomic(dev, "[PLANE:%d:%s] processing zpos value %d\n",
473 			       plane->base.id, plane->name, plane_state->zpos);
474 	}
475 
476 	sort(states, n, sizeof(*states), drm_atomic_state_zpos_cmp, NULL);
477 
478 	for (i = 0; i < n; i++) {
479 		plane = states[i]->plane;
480 
481 		states[i]->normalized_zpos = i;
482 		drm_dbg_atomic(dev, "[PLANE:%d:%s] normalized zpos value %d\n",
483 			       plane->base.id, plane->name, i);
484 	}
485 	crtc_state->zpos_changed = true;
486 
487 done:
488 	kfree(states);
489 	return ret;
490 }
491 
492 /**
493  * drm_atomic_normalize_zpos - calculate normalized zpos values for all crtcs
494  * @dev: DRM device
495  * @state: atomic state of DRM device
496  *
497  * This function calculates normalized zpos value for all modified planes in
498  * the provided atomic state of DRM device.
499  *
500  * For every CRTC this function checks new states of all planes assigned to
501  * it and calculates normalized zpos value for these planes. Planes are compared
502  * first by their zpos values, then by plane id (if zpos is equal). The plane
503  * with lowest zpos value is at the bottom. The &drm_plane_state.normalized_zpos
504  * is then filled with unique values from 0 to number of active planes in crtc
505  * minus one.
506  *
507  * RETURNS
508  * Zero for success or -errno
509  */
drm_atomic_normalize_zpos(struct drm_device * dev,struct drm_atomic_state * state)510 int drm_atomic_normalize_zpos(struct drm_device *dev,
511 			      struct drm_atomic_state *state)
512 {
513 	struct drm_crtc *crtc;
514 	struct drm_crtc_state *old_crtc_state, *new_crtc_state;
515 	struct drm_plane *plane;
516 	struct drm_plane_state *old_plane_state, *new_plane_state;
517 	int i, ret = 0;
518 
519 	for_each_oldnew_plane_in_state(state, plane, old_plane_state, new_plane_state, i) {
520 		crtc = new_plane_state->crtc;
521 		if (!crtc)
522 			continue;
523 		if (old_plane_state->zpos != new_plane_state->zpos) {
524 			new_crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
525 			new_crtc_state->zpos_changed = true;
526 		}
527 	}
528 
529 	for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
530 		if (old_crtc_state->plane_mask != new_crtc_state->plane_mask ||
531 		    new_crtc_state->zpos_changed) {
532 			ret = drm_atomic_helper_crtc_normalize_zpos(crtc,
533 								    new_crtc_state);
534 			if (ret)
535 				return ret;
536 		}
537 	}
538 	return 0;
539 }
540 EXPORT_SYMBOL(drm_atomic_normalize_zpos);
541 
542 /**
543  * drm_plane_create_blend_mode_property - create a new blend mode property
544  * @plane: drm plane
545  * @supported_modes: bitmask of supported modes, must include
546  *		     BIT(DRM_MODE_BLEND_PREMULTI). Current DRM assumption is
547  *		     that alpha is premultiplied, and old userspace can break if
548  *		     the property defaults to anything else.
549  *
550  * This creates a new property describing the blend mode.
551  *
552  * The property exposed to userspace is an enumeration property (see
553  * drm_property_create_enum()) called "pixel blend mode" and has the
554  * following enumeration values:
555  *
556  * "None":
557  *	Blend formula that ignores the pixel alpha.
558  *
559  * "Pre-multiplied":
560  *	Blend formula that assumes the pixel color values have been already
561  *	pre-multiplied with the alpha channel values.
562  *
563  * "Coverage":
564  *	Blend formula that assumes the pixel color values have not been
565  *	pre-multiplied and will do so when blending them to the background color
566  *	values.
567  *
568  * RETURNS:
569  * Zero for success or -errno
570  */
drm_plane_create_blend_mode_property(struct drm_plane * plane,unsigned int supported_modes)571 int drm_plane_create_blend_mode_property(struct drm_plane *plane,
572 					 unsigned int supported_modes)
573 {
574 	struct drm_device *dev = plane->dev;
575 	struct drm_property *prop;
576 	static const struct drm_prop_enum_list props[] = {
577 		{ DRM_MODE_BLEND_PIXEL_NONE, "None" },
578 		{ DRM_MODE_BLEND_PREMULTI, "Pre-multiplied" },
579 		{ DRM_MODE_BLEND_COVERAGE, "Coverage" },
580 	};
581 	unsigned int valid_mode_mask = BIT(DRM_MODE_BLEND_PIXEL_NONE) |
582 				       BIT(DRM_MODE_BLEND_PREMULTI)   |
583 				       BIT(DRM_MODE_BLEND_COVERAGE);
584 	int i;
585 
586 	if (WARN_ON((supported_modes & ~valid_mode_mask) ||
587 		    ((supported_modes & BIT(DRM_MODE_BLEND_PREMULTI)) == 0)))
588 		return -EINVAL;
589 
590 	prop = drm_property_create(dev, DRM_MODE_PROP_ENUM,
591 				   "pixel blend mode",
592 				   hweight32(supported_modes));
593 	if (!prop)
594 		return -ENOMEM;
595 
596 	for (i = 0; i < ARRAY_SIZE(props); i++) {
597 		int ret;
598 
599 		if (!(BIT(props[i].type) & supported_modes))
600 			continue;
601 
602 		ret = drm_property_add_enum(prop, props[i].type,
603 					    props[i].name);
604 
605 		if (ret) {
606 			drm_property_destroy(dev, prop);
607 
608 			return ret;
609 		}
610 	}
611 
612 	drm_object_attach_property(&plane->base, prop, DRM_MODE_BLEND_PREMULTI);
613 	plane->blend_mode_property = prop;
614 
615 	return 0;
616 }
617 EXPORT_SYMBOL(drm_plane_create_blend_mode_property);
618