drm: Add a new plane property to send damage during plane update

FB_DAMAGE_CLIPS is an optional plane property to mark damaged regions
on the plane in framebuffer coordinates of the framebuffer attached to
the plane.

The layout of blob data is simply an array of "struct drm_mode_rect".
Unlike plane src coordinates, damage clips are not in 16.16 fixed point.
As plane src in framebuffer cannot be negative so are damage clips. In
damage clip, x1/y1 are inclusive and x2/y2 are exclusive.

This patch also exports the kernel internal drm_rect to userspace as
drm_mode_rect. This is because "struct drm_clip_rect" is not sufficient
to represent damage for current plane size.

Driver which are interested in enabling FB_DAMAGE_CLIPS property for a
plane should enable this property using drm_plane_enable_damage_clips.

v2:
- Input validation on damage clips against framebuffer size.
- Doc update, other minor changes.

Signed-off-by: Lukasz Spintzyk <[e-mail]>
Signed-off-by: Deepak Rawat <[e-mail]>
Reviewed-by: Daniel Vetter <[e-mail]>
Reviewed-by: Thomas Hellstrom <[e-mail]>
Signed-off-by: Thomas Hellstrom <[e-mail]>

Documentation/gpu/drm-kms.rst

···
 .. kernel-doc:: drivers/gpu/drm/drm_blend.c
    :export:
 
+FB_DAMAGE_CLIPS
+~~~~~~~~~~~~~~~
+
+.. kernel-doc:: drivers/gpu/drm/drm_damage_helper.c
+   :doc: overview
+
+.. kernel-doc:: drivers/gpu/drm/drm_damage_helper.c
+   :export:
+
+.. kernel-doc:: include/drm/drm_damage_helper.h
+   :internal:
+
 Color Management Properties
 ---------------------------
 

drivers/gpu/drm/Makefile

···
 		drm_kms_helper_common.o drm_dp_dual_mode_helper.o \
 		drm_simple_kms_helper.o drm_modeset_helper.o \
 		drm_scdc_helper.o drm_gem_framebuffer_helper.o \
-		drm_atomic_state_helper.o
+		drm_atomic_state_helper.o drm_damage_helper.o
 
 drm_kms_helper-$(CONFIG_DRM_PANEL_BRIDGE) += bridge/panel.o
 drm_kms_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fb_helper.o

drivers/gpu/drm/drm_atomic.c

···
 	struct drm_crtc *crtc = new_plane_state->crtc;
 	const struct drm_framebuffer *fb = new_plane_state->fb;
 	unsigned int fb_width, fb_height;
+	struct drm_mode_rect *clips;
+	uint32_t num_clips;
 	int ret;
 
 	/* either *both* CRTC and FB must be set, or neither */
···
 				 ((new_plane_state->src_y & 0xffff) * 15625) >> 10,
 				 fb->width, fb->height);
 		return -ENOSPC;
+	}
+
+	clips = drm_plane_get_damage_clips(new_plane_state);
+	num_clips = drm_plane_get_damage_clips_count(new_plane_state);
+
+	/* Make sure damage clips are valid and inside the fb. */
+	while (num_clips > 0) {
+		if (clips->x1 >= clips->x2 ||
+		    clips->y1 >= clips->y2 ||
+		    clips->x1 < 0 ||
+		    clips->y1 < 0 ||
+		    clips->x2 > fb_width ||
+		    clips->y2 > fb_height) {
+			DRM_DEBUG_ATOMIC("[PLANE:%d:%s] invalid damage clip %d %d %d %d\n",
+					 plane->base.id, plane->name, clips->x1,
+					 clips->y1, clips->x2, clips->y2);
+			return -EINVAL;
+		}
+		clips++;
+		num_clips--;
 	}
 
 	if (plane_switching_crtc(old_plane_state, new_plane_state)) {

drivers/gpu/drm/drm_atomic_uapi.c

···
 {
 	struct drm_device *dev = plane->dev;
 	struct drm_mode_config *config = &dev->mode_config;
+	bool replaced = false;
+	int ret;
 
 	if (property == config->prop_fb_id) {
 		struct drm_framebuffer *fb = drm_framebuffer_lookup(dev, NULL, val);
···
 		state->color_encoding = val;
 	} else if (property == plane->color_range_property) {
 		state->color_range = val;
+	} else if (property == config->prop_fb_damage_clips) {
+		ret = drm_atomic_replace_property_blob_from_id(dev,
+					&state->fb_damage_clips,
+					val,
+					-1,
+					sizeof(struct drm_rect),
+					&replaced);
+		return ret;
 	} else if (plane->funcs->atomic_set_property) {
 		return plane->funcs->atomic_set_property(plane, state,
 				property, val);
···
 		*val = state->color_encoding;
 	} else if (property == plane->color_range_property) {
 		*val = state->color_range;
+	} else if (property == config->prop_fb_damage_clips) {
+		*val = (state->fb_damage_clips) ?
+			state->fb_damage_clips->base.id : 0;
 	} else if (plane->funcs->atomic_get_property) {
 		return plane->funcs->atomic_get_property(plane, state, property, val);
 	} else {

drivers/gpu/drm/drm_damage_helper.c

···
+// SPDX-License-Identifier: GPL-2.0 OR MIT
+/**************************************************************************
+ *
+ * Copyright (c) 2018 VMware, Inc., Palo Alto, CA., USA
+ * All Rights Reserved.
+ *
+ * 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, sub license, 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 NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS 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.
+ *
+ * Authors:
+ * Deepak Rawat <[e-mail]>
+ *
+ **************************************************************************/
+
+#include <drm/drm_damage_helper.h>
+
+/**
+ * DOC: overview
+ *
+ * FB_DAMAGE_CLIPS is an optional plane property which provides a means to
+ * specify a list of damage rectangles on a plane in framebuffer coordinates of
+ * the framebuffer attached to the plane. In current context damage is the area
+ * of plane framebuffer that has changed since last plane update (also called
+ * page-flip), irrespective of whether currently attached framebuffer is same as
+ * framebuffer attached during last plane update or not.
+ *
+ * FB_DAMAGE_CLIPS is a hint to kernel which could be helpful for some drivers
+ * to optimize internally especially for virtual devices where each framebuffer
+ * change needs to be transmitted over network, usb, etc.
+ *
+ * Since FB_DAMAGE_CLIPS is a hint so it is an optional property. User-space can
+ * ignore damage clips property and in that case driver will do a full plane
+ * update. In case damage clips are provided then it is guaranteed that the area
+ * inside damage clips will be updated to plane. For efficiency driver can do
+ * full update or can update more than specified in damage clips. Since driver
+ * is free to read more, user-space must always render the entire visible
+ * framebuffer. Otherwise there can be corruptions. Also, if a user-space
+ * provides damage clips which doesn't encompass the actual damage to
+ * framebuffer (since last plane update) can result in incorrect rendering.
+ *
+ * FB_DAMAGE_CLIPS is a blob property with the layout of blob data is simply an
+ * array of &drm_mode_rect. Unlike plane &drm_plane_state.src coordinates,
+ * damage clips are not in 16.16 fixed point. Similar to plane src in
+ * framebuffer, damage clips cannot be negative. In damage clip, x1/y1 are
+ * inclusive and x2/y2 are exclusive. While kernel does not error for overlapped
+ * damage clips, it is strongly discouraged.
+ *
+ * Drivers that are interested in damage interface for plane should enable
+ * FB_DAMAGE_CLIPS property by calling drm_plane_enable_fb_damage_clips().
+ */
+
+/**
+ * drm_plane_enable_fb_damage_clips - Enables plane fb damage clips property.
+ * @plane: Plane on which to enable damage clips property.
+ *
+ * This function lets driver to enable the damage clips property on a plane.
+ */
+void drm_plane_enable_fb_damage_clips(struct drm_plane *plane)
+{
+	struct drm_device *dev = plane->dev;
+	struct drm_mode_config *config = &dev->mode_config;
+
+	drm_object_attach_property(&plane->base, config->prop_fb_damage_clips,
+				   0);
+}
+EXPORT_SYMBOL(drm_plane_enable_fb_damage_clips);

drivers/gpu/drm/drm_mode_config.c

···
 		return -ENOMEM;
 	dev->mode_config.prop_crtc_id = prop;
 
+	prop = drm_property_create(dev, DRM_MODE_PROP_BLOB, "FB_DAMAGE_CLIPS",
+				   0);
+	if (!prop)
+		return -ENOMEM;
+	dev->mode_config.prop_fb_damage_clips = prop;
+
 	prop = drm_property_create_bool(dev, DRM_MODE_PROP_ATOMIC,
 			"ACTIVE");
 	if (!prop)

include/drm/drm_damage_helper.h

···
+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+/**************************************************************************
+ *
+ * Copyright (c) 2018 VMware, Inc., Palo Alto, CA., USA
+ * All Rights Reserved.
+ *
+ * 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, sub license, 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 NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS 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.
+ *
+ * Authors:
+ * Deepak Rawat <[e-mail]>
+ *
+ **************************************************************************/
+
+#ifndef DRM_DAMAGE_HELPER_H_
+#define DRM_DAMAGE_HELPER_H_
+
+#include <drm/drm_atomic_helper.h>
+
+void drm_plane_enable_fb_damage_clips(struct drm_plane *plane);
+
+#endif

include/drm/drm_mode_config.h

···
 	 */
 	struct drm_property *prop_crtc_id;
 	/**
+	 * @prop_fb_damage_clips: Optional plane property to mark damaged
+	 * regions on the plane in framebuffer coordinates of the framebuffer
+	 * attached to the plane.
+	 *
+	 * The layout of blob data is simply an array of &drm_mode_rect. Unlike
+	 * plane src coordinates, damage clips are not in 16.16 fixed point.
+	 */
+	struct drm_property *prop_fb_damage_clips;
+	/**
 	 * @prop_active: Default atomic CRTC property to control the active
 	 * state, which is the simplified implementation for DPMS in atomic
 	 * drivers.

include/drm/drm_plane.h

···
 	 */
 	enum drm_color_range color_range;
 
+	/**
+	 * @fb_damage_clips:
+	 *
+	 * Blob representing damage (area in plane framebuffer that changed
+	 * since last plane update) as an array of &drm_mode_rect in framebuffer
+	 * coodinates of the attached framebuffer. Note that unlike plane src,
+	 * damage clips are not in 16.16 fixed point.
+	 */
+	struct drm_property_blob *fb_damage_clips;
+
 	/** @src: clipped source coordinates of the plane (in 16.16) */
 	/** @dst: clipped destination coordinates of the plane */
 	struct drm_rect src, dst;
···
 
 bool drm_any_plane_has_format(struct drm_device *dev,
 			      u32 format, u64 modifier);
+/**
+ * drm_plane_get_damage_clips_count - Returns damage clips count.
+ * @state: Plane state.
+ *
+ * Simple helper to get the number of &drm_mode_rect clips set by user-space
+ * during plane update.
+ *
+ * Return: Number of clips in plane fb_damage_clips blob property.
+ */
+static inline unsigned int
+drm_plane_get_damage_clips_count(const struct drm_plane_state *state)
+{
+	return (state && state->fb_damage_clips) ?
+		state->fb_damage_clips->length/sizeof(struct drm_mode_rect) : 0;
+}
+
+/**
+ * drm_plane_get_damage_clips - Returns damage clips.
+ * @state: Plane state.
+ *
+ * Note that this function returns uapi type &drm_mode_rect.
+ *
+ * Return: Damage clips in plane fb_damage_clips blob property.
+ */
+static inline struct drm_mode_rect *
+drm_plane_get_damage_clips(const struct drm_plane_state *state)
+{
+	return (struct drm_mode_rect *)((state && state->fb_damage_clips) ?
+					state->fb_damage_clips->data : NULL);
+}
 
 #endif

include/uapi/drm/drm_mode.h

···
 	__u32 lessee_id;
 };
 
+/**
+ * struct drm_mode_rect - Two dimensional rectangle.
+ * @x1: Horizontal starting coordinate (inclusive).
+ * @y1: Vertical starting coordinate (inclusive).
+ * @x2: Horizontal ending coordinate (exclusive).
+ * @y2: Vertical ending coordinate (exclusive).
+ *
+ * With drm subsystem using struct drm_rect to manage rectangular area this
+ * export it to user-space.
+ *
+ * Currently used by drm_mode_atomic blob property FB_DAMAGE_CLIPS.
+ */
+struct drm_mode_rect {
+	__s32 x1;
+	__s32 y1;
+	__s32 x2;
+	__s32 y2;
+};
+
 #if defined(__cplusplus)
 }
 #endif