[linux-block.git] / drivers / gpu / drm / drm_plane_helper.c

/*
 * Copyright (C) 2014 Intel Corporation
 *
 * DRM universal plane helper functions
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <linux/list.h>

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_atomic_uapi.h>
#include <drm/drm_crtc_helper.h>
#include <drm/drm_device.h>
#include <drm/drm_drv.h>
#include <drm/drm_encoder.h>
#include <drm/drm_plane_helper.h>
#include <drm/drm_print.h>
#include <drm/drm_rect.h>

#define SUBPIXEL_MASK 0xffff

/**
 * DOC: overview
 *
 * This helper library has two parts. The first part has support to implement
 * primary plane support on top of the normal CRTC configuration interface.
 * Since the legacy &drm_mode_config_funcs.set_config interface ties the primary
 * plane together with the CRTC state this does not allow userspace to disable
 * the primary plane itself. The default primary plane only expose XRBG8888 and
 * ARGB8888 as valid pixel formats for the attached framebuffer.
 *
 * Drivers are highly recommended to implement proper support for primary
 * planes, and newly merged drivers must not rely upon these transitional
 * helpers.
 *
 * The second part also implements transitional helpers which allow drivers to
 * gradually switch to the atomic helper infrastructure for plane updates. Once
 * that switch is complete drivers shouldn't use these any longer, instead using
 * the proper legacy implementations for update and disable plane hooks provided
 * by the atomic helpers.
 *
 * Again drivers are strongly urged to switch to the new interfaces.
 *
 * The plane helpers share the function table structures with other helpers,
 * specifically also the atomic helpers. See &struct drm_plane_helper_funcs for
 * the details.
 */

/*
 * Returns the connectors currently associated with a CRTC.  This function
 * should be called twice:  once with a NULL connector list to retrieve
 * the list size, and once with the properly allocated list to be filled in.
 */
static int get_connectors_for_crtc(struct drm_crtc *crtc,
				   struct drm_connector **connector_list,
				   int num_connectors)
{
	struct drm_device *dev = crtc->dev;
	struct drm_connector *connector;
	struct drm_connector_list_iter conn_iter;
	int count = 0;

	/*
	 * Note: Once we change the plane hooks to more fine-grained locking we
	 * need to grab the connection_mutex here to be able to make these
	 * checks.
	 */
	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));

	drm_connector_list_iter_begin(dev, &conn_iter);
	drm_for_each_connector_iter(connector, &conn_iter) {
		if (connector->encoder && connector->encoder->crtc == crtc) {
			if (connector_list != NULL && count < num_connectors)
				*(connector_list++) = connector;

			count++;
		}
	}
	drm_connector_list_iter_end(&conn_iter);

	return count;
}

static int drm_plane_helper_check_update(struct drm_plane *plane,
					 struct drm_crtc *crtc,
					 struct drm_framebuffer *fb,
					 struct drm_rect *src,
					 struct drm_rect *dst,
					 unsigned int rotation,
					 int min_scale,
					 int max_scale,
					 bool can_position,
					 bool can_update_disabled,
					 bool *visible)
{
	struct drm_plane_state plane_state = {
		.plane = plane,
		.crtc = crtc,
		.fb = fb,
		.src_x = src->x1,
		.src_y = src->y1,
		.src_w = drm_rect_width(src),
		.src_h = drm_rect_height(src),
		.crtc_x = dst->x1,
		.crtc_y = dst->y1,
		.crtc_w = drm_rect_width(dst),
		.crtc_h = drm_rect_height(dst),
		.rotation = rotation,
	};
	struct drm_crtc_state crtc_state = {
		.crtc = crtc,
		.enable = crtc->enabled,
		.mode = crtc->mode,
	};
	int ret;

	ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
						  min_scale, max_scale,
						  can_position,
						  can_update_disabled);
	if (ret)
		return ret;

	*src = plane_state.src;
	*dst = plane_state.dst;
	*visible = plane_state.visible;

	return 0;
}

/**
 * drm_plane_helper_update_primary - Helper for updating primary planes
 * @plane: plane to update
 * @crtc: the plane's new CRTC
 * @fb: the plane's new framebuffer
 * @crtc_x: x coordinate within CRTC
 * @crtc_y: y coordinate within CRTC
 * @crtc_w: width coordinate within CRTC
 * @crtc_h: height coordinate within CRTC
 * @src_x: x coordinate within source
 * @src_y: y coordinate within source
 * @src_w: width coordinate within source
 * @src_h: height coordinate within source
 * @ctx: modeset locking context
 *
 * This helper validates the given parameters and updates the primary plane.
 *
 * This function is only useful for non-atomic modesetting. Don't use
 * it in new drivers.
 *
 * Returns:
 * Zero on success, or an errno code otherwise.
 */
int drm_plane_helper_update_primary(struct drm_plane *plane, struct drm_crtc *crtc,
				    struct drm_framebuffer *fb,
				    int crtc_x, int crtc_y,
				    unsigned int crtc_w, unsigned int crtc_h,
				    uint32_t src_x, uint32_t src_y,
				    uint32_t src_w, uint32_t src_h,
				    struct drm_modeset_acquire_ctx *ctx)
{
	struct drm_mode_set set = {
		.crtc = crtc,
		.fb = fb,
		.mode = &crtc->mode,
		.x = src_x >> 16,
		.y = src_y >> 16,
	};
	struct drm_rect src = {
		.x1 = src_x,
		.y1 = src_y,
		.x2 = src_x + src_w,
		.y2 = src_y + src_h,
	};
	struct drm_rect dest = {
		.x1 = crtc_x,
		.y1 = crtc_y,
		.x2 = crtc_x + crtc_w,
		.y2 = crtc_y + crtc_h,
	};
	struct drm_device *dev = plane->dev;
	struct drm_connector **connector_list;
	int num_connectors, ret;
	bool visible;

	if (drm_WARN_ON_ONCE(dev, drm_drv_uses_atomic_modeset(dev)))
		return -EINVAL;

	ret = drm_plane_helper_check_update(plane, crtc, fb,
					    &src, &dest,
					    DRM_MODE_ROTATE_0,
					    DRM_PLANE_NO_SCALING,
					    DRM_PLANE_NO_SCALING,
					    false, false, &visible);
	if (ret)
		return ret;

	if (!visible)
		/*
		 * Primary plane isn't visible.  Note that unless a driver
		 * provides their own disable function, this will just
		 * wind up returning -EINVAL to userspace.
		 */
		return plane->funcs->disable_plane(plane, ctx);

	/* Find current connectors for CRTC */
	num_connectors = get_connectors_for_crtc(crtc, NULL, 0);
	BUG_ON(num_connectors == 0);
	connector_list = kcalloc(num_connectors, sizeof(*connector_list),
				 GFP_KERNEL);
	if (!connector_list)
		return -ENOMEM;
	get_connectors_for_crtc(crtc, connector_list, num_connectors);

	set.connectors = connector_list;
	set.num_connectors = num_connectors;

	/*
	 * We call set_config() directly here rather than using
	 * drm_mode_set_config_internal.  We're reprogramming the same
	 * connectors that were already in use, so we shouldn't need the extra
	 * cross-CRTC fb refcounting to accommodate stealing connectors.
	 * drm_mode_setplane() already handles the basic refcounting for the
	 * framebuffers involved in this operation.
	 */
	ret = crtc->funcs->set_config(&set, ctx);

	kfree(connector_list);
	return ret;
}
EXPORT_SYMBOL(drm_plane_helper_update_primary);

/**
 * drm_plane_helper_disable_primary - Helper for disabling primary planes
 * @plane: plane to disable
 * @ctx: modeset locking context
 *
 * This helper returns an error when trying to disable the primary
 * plane.
 *
 * This function is only useful for non-atomic modesetting. Don't use
 * it in new drivers.
 *
 * Returns:
 * An errno code.
 */
int drm_plane_helper_disable_primary(struct drm_plane *plane,
				     struct drm_modeset_acquire_ctx *ctx)
{
	struct drm_device *dev = plane->dev;

	drm_WARN_ON_ONCE(dev, drm_drv_uses_atomic_modeset(dev));

	return -EINVAL;
}
EXPORT_SYMBOL(drm_plane_helper_disable_primary);

/**
 * drm_plane_helper_destroy() - Helper for primary plane destruction
 * @plane: plane to destroy
 *
 * Provides a default plane destroy handler for primary planes.  This handler
 * is called during CRTC destruction.  We disable the primary plane, remove
 * it from the DRM plane list, and deallocate the plane structure.
 */
void drm_plane_helper_destroy(struct drm_plane *plane)
{
	drm_plane_cleanup(plane);
	kfree(plane);
}
EXPORT_SYMBOL(drm_plane_helper_destroy);

/**
 * drm_plane_helper_atomic_check() - Helper to check plane atomic-state
 * @plane: plane to check
 * @state: atomic state object
 *
 * Provides a default plane-state check handler for planes whose atomic-state
 * scale and positioning are not expected to change since the plane is always
 * a fullscreen scanout buffer.
 *
 * This is often the case for the primary plane of simple framebuffers. See
 * also drm_crtc_helper_atomic_check() for the respective CRTC-state check
 * helper function.
 *
 * RETURNS:
 * Zero on success, or an errno code otherwise.
 */
int drm_plane_helper_atomic_check(struct drm_plane *plane, struct drm_atomic_state *state)
{
	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state, plane);
	struct drm_crtc *new_crtc = new_plane_state->crtc;
	struct drm_crtc_state *new_crtc_state = NULL;

	if (new_crtc)
		new_crtc_state = drm_atomic_get_new_crtc_state(state, new_crtc);

	return drm_atomic_helper_check_plane_state(new_plane_state, new_crtc_state,
						   DRM_PLANE_NO_SCALING,
						   DRM_PLANE_NO_SCALING,
						   false, false);
}
EXPORT_SYMBOL(drm_plane_helper_atomic_check);
Commit	Line	Data
c103d1cf MR	1	/*
	2	* Copyright (C) 2014 Intel Corporation
	3	*
	4	* DRM universal plane helper functions
	5	*
	6	* Permission is hereby granted, free of charge, to any person obtaining a
	7	* copy of this software and associated documentation files (the "Software"),
	8	* to deal in the Software without restriction, including without limitation
	9	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	10	* and/or sell copies of the Software, and to permit persons to whom the
	11	* Software is furnished to do so, subject to the following conditions:
	12	*
	13	* The above copyright notice and this permission notice (including the next
	14	* paragraph) shall be included in all copies or substantial portions of the
	15	* Software.
	16	*
	17	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	18	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	19	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	20	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	21	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	22	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	23	* SOFTWARE.
	24	*/
	25
	26	#include <linux/list.h>
0500c04e	27
321ebf04	28	#include <drm/drm_atomic.h>
0500c04e	29	#include <drm/drm_atomic_helper.h>
72fdb40c	30	#include <drm/drm_atomic_uapi.h>
acf24a39	31	#include <drm/drm_crtc_helper.h>
0500c04e	32	#include <drm/drm_device.h>
fa0706e9	33	#include <drm/drm_drv.h>
9338203c	34	#include <drm/drm_encoder.h>
0500c04e	35	#include <drm/drm_plane_helper.h>
fa0706e9	36	#include <drm/drm_print.h>
0500c04e	37	#include <drm/drm_rect.h>
c103d1cf MR	38
	39	#define SUBPIXEL_MASK 0xffff
	40
3150c7d0 DV	41	/**
	42	* DOC: overview
	43	*
	44	* This helper library has two parts. The first part has support to implement
	45	* primary plane support on top of the normal CRTC configuration interface.
6806cdf9 DV	46	* Since the legacy &drm_mode_config_funcs.set_config interface ties the primary
6806cdf9 DV	47	* plane together with the CRTC state this does not allow userspace to disable
6b6fce62 DV	48	* the primary plane itself. The default primary plane only expose XRBG8888 and
6b6fce62 DV	49	* ARGB8888 as valid pixel formats for the attached framebuffer.
3150c7d0 DV	50	*
	51	* Drivers are highly recommended to implement proper support for primary
	52	* planes, and newly merged drivers must not rely upon these transitional
	53	* helpers.
	54	*
	55	* The second part also implements transitional helpers which allow drivers to
	56	* gradually switch to the atomic helper infrastructure for plane updates. Once
	57	* that switch is complete drivers shouldn't use these any longer, instead using
	58	* the proper legacy implementations for update and disable plane hooks provided
	59	* by the atomic helpers.
	60	*
	61	* Again drivers are strongly urged to switch to the new interfaces.
092d01da DV	62	*
092d01da DV	63	* The plane helpers share the function table structures with other helpers,
ea0dd85a	64	* specifically also the atomic helpers. See &struct drm_plane_helper_funcs for
092d01da	65	* the details.
3150c7d0 DV	66	*/
3150c7d0 DV	67
c103d1cf MR	68	/*
	69	* Returns the connectors currently associated with a CRTC. This function
	70	* should be called twice: once with a NULL connector list to retrieve
	71	* the list size, and once with the properly allocated list to be filled in.
	72	*/
	73	static int get_connectors_for_crtc(struct drm_crtc *crtc,
	74	struct drm_connector **connector_list,
	75	int num_connectors)
	76	{
	77	struct drm_device *dev = crtc->dev;
	78	struct drm_connector *connector;
c36a3254	79	struct drm_connector_list_iter conn_iter;
c103d1cf MR	80	int count = 0;
c103d1cf MR	81
6e9f798d DV	82	/*
	83	* Note: Once we change the plane hooks to more fine-grained locking we
	84	* need to grab the connection_mutex here to be able to make these
	85	* checks.
	86	*/
51fd371b	87	WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
6e9f798d	88
b982dab1	89	drm_connector_list_iter_begin(dev, &conn_iter);
c36a3254	90	drm_for_each_connector_iter(connector, &conn_iter) {
c103d1cf MR	91	if (connector->encoder && connector->encoder->crtc == crtc) {
	92	if (connector_list != NULL && count < num_connectors)
	93	*(connector_list++) = connector;
	94
	95	count++;
	96	}
9a9f5ce8	97	}
b982dab1	98	drm_connector_list_iter_end(&conn_iter);
c103d1cf MR	99
	100	return count;
	101	}
	102
84c08517 DV	103	static int drm_plane_helper_check_update(struct drm_plane *plane,
	104	struct drm_crtc *crtc,
	105	struct drm_framebuffer *fb,
	106	struct drm_rect *src,
	107	struct drm_rect *dst,
	108	unsigned int rotation,
	109	int min_scale,
	110	int max_scale,
	111	bool can_position,
	112	bool can_update_disabled,
	113	bool *visible)
df86af91	114	{
10b47ee0	115	struct drm_plane_state plane_state = {
df86af91 VS	116	.plane = plane,
	117	.crtc = crtc,
	118	.fb = fb,
	119	.src_x = src->x1,
	120	.src_y = src->y1,
	121	.src_w = drm_rect_width(src),
	122	.src_h = drm_rect_height(src),
	123	.crtc_x = dst->x1,
	124	.crtc_y = dst->y1,
	125	.crtc_w = drm_rect_width(dst),
	126	.crtc_h = drm_rect_height(dst),
	127	.rotation = rotation,
df86af91	128	};
10b47ee0 VS	129	struct drm_crtc_state crtc_state = {
	130	.crtc = crtc,
	131	.enable = crtc->enabled,
81af63a4	132	.mode = crtc->mode,
10b47ee0	133	};
df86af91 VS	134	int ret;
df86af91 VS	135
a01cb8ba	136	ret = drm_atomic_helper_check_plane_state(&plane_state, &crtc_state,
81af63a4	137	min_scale, max_scale,
a01cb8ba VS	138	can_position,
a01cb8ba VS	139	can_update_disabled);
df86af91 VS	140	if (ret)
	141	return ret;
	142
10b47ee0 VS	143	*src = plane_state.src;
	144	*dst = plane_state.dst;
	145	*visible = plane_state.visible;
df86af91 VS	146
	147	return 0;
	148	}
7daf8d54	149
30c63715 TZ	150	/**
	151	* drm_plane_helper_update_primary - Helper for updating primary planes
	152	* @plane: plane to update
	153	* @crtc: the plane's new CRTC
	154	* @fb: the plane's new framebuffer
	155	* @crtc_x: x coordinate within CRTC
	156	* @crtc_y: y coordinate within CRTC
	157	* @crtc_w: width coordinate within CRTC
	158	* @crtc_h: height coordinate within CRTC
	159	* @src_x: x coordinate within source
	160	* @src_y: y coordinate within source
	161	* @src_w: width coordinate within source
	162	* @src_h: height coordinate within source
	163	* @ctx: modeset locking context
	164	*
	165	* This helper validates the given parameters and updates the primary plane.
	166	*
	167	* This function is only useful for non-atomic modesetting. Don't use
	168	* it in new drivers.
	169	*
	170	* Returns:
	171	* Zero on success, or an errno code otherwise.
	172	*/
	173	int drm_plane_helper_update_primary(struct drm_plane plane, struct drm_crtc crtc,
	174	struct drm_framebuffer *fb,
	175	int crtc_x, int crtc_y,
	176	unsigned int crtc_w, unsigned int crtc_h,
	177	uint32_t src_x, uint32_t src_y,
	178	uint32_t src_w, uint32_t src_h,
	179	struct drm_modeset_acquire_ctx *ctx)
c103d1cf MR	180	{
	181	struct drm_mode_set set = {
	182	.crtc = crtc,
	183	.fb = fb,
	184	.mode = &crtc->mode,
	185	.x = src_x >> 16,
	186	.y = src_y >> 16,
	187	};
7daf8d54 MR	188	struct drm_rect src = {
	189	.x1 = src_x,
	190	.y1 = src_y,
	191	.x2 = src_x + src_w,
	192	.y2 = src_y + src_h,
	193	};
c103d1cf MR	194	struct drm_rect dest = {
	195	.x1 = crtc_x,
	196	.y1 = crtc_y,
	197	.x2 = crtc_x + crtc_w,
	198	.y2 = crtc_y + crtc_h,
	199	};
fa0706e9	200	struct drm_device *dev = plane->dev;
c103d1cf	201	struct drm_connector **connector_list;
c103d1cf	202	int num_connectors, ret;
7daf8d54	203	bool visible;
c103d1cf	204
fa0706e9 TZ	205	if (drm_WARN_ON_ONCE(dev, drm_drv_uses_atomic_modeset(dev)))
	206	return -EINVAL;
	207
7daf8d54	208	ret = drm_plane_helper_check_update(plane, crtc, fb,
81af63a4	209	&src, &dest,
c2c446ad	210	DRM_MODE_ROTATE_0,
cce32e4e TZ	211	DRM_PLANE_NO_SCALING,
cce32e4e TZ	212	DRM_PLANE_NO_SCALING,
7daf8d54	213	false, false, &visible);
c103d1cf MR	214	if (ret)
	215	return ret;
	216
7daf8d54 MR	217	if (!visible)
	218	/*
	219	* Primary plane isn't visible. Note that unless a driver
	220	* provides their own disable function, this will just
	221	* wind up returning -EINVAL to userspace.
	222	*/
19315294	223	return plane->funcs->disable_plane(plane, ctx);
7daf8d54	224
c103d1cf MR	225	/* Find current connectors for CRTC */
	226	num_connectors = get_connectors_for_crtc(crtc, NULL, 0);
	227	BUG_ON(num_connectors == 0);
4b947b1c	228	connector_list = kcalloc(num_connectors, sizeof(*connector_list),
c103d1cf MR	229	GFP_KERNEL);
	230	if (!connector_list)
	231	return -ENOMEM;
	232	get_connectors_for_crtc(crtc, connector_list, num_connectors);
	233
	234	set.connectors = connector_list;
	235	set.num_connectors = num_connectors;
	236
	237	/*
0fe27f06	238	* We call set_config() directly here rather than using
c103d1cf MR	239	* drm_mode_set_config_internal. We're reprogramming the same
c103d1cf MR	240	* connectors that were already in use, so we shouldn't need the extra
0ae865ef	241	* cross-CRTC fb refcounting to accommodate stealing connectors.
c103d1cf MR	242	* drm_mode_setplane() already handles the basic refcounting for the
	243	* framebuffers involved in this operation.
	244	*/
a4eff9aa	245	ret = crtc->funcs->set_config(&set, ctx);
c103d1cf MR	246
	247	kfree(connector_list);
	248	return ret;
	249	}
30c63715	250	EXPORT_SYMBOL(drm_plane_helper_update_primary);
c103d1cf	251
30c63715 TZ	252	/**
	253	* drm_plane_helper_disable_primary - Helper for disabling primary planes
	254	* @plane: plane to disable
	255	* @ctx: modeset locking context
	256	*
	257	* This helper returns an error when trying to disable the primary
	258	* plane.
	259	*
	260	* This function is only useful for non-atomic modesetting. Don't use
	261	* it in new drivers.
	262	*
	263	* Returns:
	264	* An errno code.
	265	*/
	266	int drm_plane_helper_disable_primary(struct drm_plane *plane,
	267	struct drm_modeset_acquire_ctx *ctx)
c103d1cf	268	{
fa0706e9 TZ	269	struct drm_device *dev = plane->dev;
	270
	271	drm_WARN_ON_ONCE(dev, drm_drv_uses_atomic_modeset(dev));
	272
b6ccd7b9	273	return -EINVAL;
c103d1cf	274	}
30c63715	275	EXPORT_SYMBOL(drm_plane_helper_disable_primary);
c103d1cf MR	276
c103d1cf MR	277	/**
30c63715	278	* drm_plane_helper_destroy() - Helper for primary plane destruction
c103d1cf MR	279	* @plane: plane to destroy
	280	*
	281	* Provides a default plane destroy handler for primary planes. This handler
	282	* is called during CRTC destruction. We disable the primary plane, remove
	283	* it from the DRM plane list, and deallocate the plane structure.
	284	*/
30c63715	285	void drm_plane_helper_destroy(struct drm_plane *plane)
c103d1cf	286	{
c103d1cf MR	287	drm_plane_cleanup(plane);
	288	kfree(plane);
	289	}
30c63715	290	EXPORT_SYMBOL(drm_plane_helper_destroy);
8401bd36 JMC	291
	292	/**
	293	* drm_plane_helper_atomic_check() - Helper to check plane atomic-state
	294	* @plane: plane to check
	295	* @state: atomic state object
	296	*
	297	* Provides a default plane-state check handler for planes whose atomic-state
	298	* scale and positioning are not expected to change since the plane is always
	299	* a fullscreen scanout buffer.
	300	*
7fed7fa3 JMC	301	* This is often the case for the primary plane of simple framebuffers. See
	302	* also drm_crtc_helper_atomic_check() for the respective CRTC-state check
	303	* helper function.
8401bd36 JMC	304	*
	305	* RETURNS:
	306	* Zero on success, or an errno code otherwise.
	307	*/
	308	int drm_plane_helper_atomic_check(struct drm_plane plane, struct drm_atomic_state state)
	309	{
	310	struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state, plane);
	311	struct drm_crtc *new_crtc = new_plane_state->crtc;
	312	struct drm_crtc_state *new_crtc_state = NULL;
	313
	314	if (new_crtc)
	315	new_crtc_state = drm_atomic_get_new_crtc_state(state, new_crtc);
	316
	317	return drm_atomic_helper_check_plane_state(new_plane_state, new_crtc_state,
	318	DRM_PLANE_NO_SCALING,
	319	DRM_PLANE_NO_SCALING,
	320	false, false);
	321	}
	322	EXPORT_SYMBOL(drm_plane_helper_atomic_check);