[PATCH v2 1/2] drm/blend: Add per-plane pixel blend mode property
Brian Starkey
brian.starkey at arm.com
Wed May 30 13:27:55 UTC 2018
Hi Lowry,
On Wed, May 30, 2018 at 07:23:53PM +0800, Lowry Li wrote:
>Pixel blend modes represent the alpha blending equation
>selection, describing how the pixels from the current
>plane are composited with the background.
>
>Add a pixel_blend_mode to drm_plane_state and a
>blend_mode_property to drm_plane, and related support
>functions.
>
>Defines three blend modes in drm_blend.h.
>
>Signed-off-by: Lowry Li <lowry.li at arm.com>
With or without the kerneldoc tweaks I've suggested below, this patch
is:
Reviewed-by: Brian Starkey <brian.starkey at arm.com>
>---
> drivers/gpu/drm/drm_atomic.c | 4 ++
> drivers/gpu/drm/drm_atomic_helper.c | 1 +
> drivers/gpu/drm/drm_blend.c | 110 ++++++++++++++++++++++++++++++++++++
> include/drm/drm_blend.h | 6 ++
> include/drm/drm_plane.h | 6 ++
> 5 files changed, 127 insertions(+)
>
>diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
>index 7d25c42..467f8de 100644
>--- a/drivers/gpu/drm/drm_atomic.c
>+++ b/drivers/gpu/drm/drm_atomic.c
>@@ -783,6 +783,8 @@ static int drm_atomic_plane_set_property(struct drm_plane *plane,
> state->src_w = val;
> } else if (property == config->prop_src_h) {
> state->src_h = val;
>+ } else if (property == plane->blend_mode_property) {
>+ state->pixel_blend_mode = val;
> } else if (property == plane->rotation_property) {
> if (!is_power_of_2(val & DRM_MODE_ROTATE_MASK))
> return -EINVAL;
>@@ -848,6 +850,8 @@ static int drm_atomic_plane_set_property(struct drm_plane *plane,
> *val = state->src_w;
> } else if (property == config->prop_src_h) {
> *val = state->src_h;
>+ } else if (property == plane->blend_mode_property) {
>+ *val = state->pixel_blend_mode;
> } else if (property == plane->rotation_property) {
> *val = state->rotation;
> } else if (property == plane->zpos_property) {
>diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
>index c356545..ddbd0d2 100644
>--- a/drivers/gpu/drm/drm_atomic_helper.c
>+++ b/drivers/gpu/drm/drm_atomic_helper.c
>@@ -3484,6 +3484,7 @@ void drm_atomic_helper_plane_reset(struct drm_plane *plane)
> if (plane->state) {
> plane->state->plane = plane;
> plane->state->rotation = DRM_MODE_ROTATE_0;
>+ plane->state->pixel_blend_mode = DRM_MODE_BLEND_PREMULTI;
> }
> }
> EXPORT_SYMBOL(drm_atomic_helper_plane_reset);
>diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
>index 5a81e1b..4ac45da 100644
>--- a/drivers/gpu/drm/drm_blend.c
>+++ b/drivers/gpu/drm/drm_blend.c
>@@ -100,6 +100,41 @@
> * planes. Without this property the primary plane is always below the cursor
> * plane, and ordering between all other planes is undefined.
> *
>+ * pixel blend mode:
>+ * Pixel blend mode is set up with drm_plane_create_blend_mode_property().
>+ * It adds a blend mode for alpha blending equation selection, describing
>+ * how the pixels from the current plane are composited with the
>+ * background.
>+ *
>+ * Three alpha blending equations(note that the fg.rgb or bg.rgb notation
>+ * means each of the R, G or B channels for the foreground and background
>+ * colors, respectively):
>+ *
>+ * "None": Blend formula that ignores the pixel alpha.
>+ * out.rgb = plane_alpha * fg.rgb + (1 - plane_alpha) * bg.rgb
>+ *
>+ * "Pre-multiplied": Blend formula that assumes the pixel color values
>+ * have been already pre-multiplied with the alpha
>+ * channel values.
>+ * out.rgb = plane_alpha * fg.rgb + (1 - (plane_alpha * fg.alpha)) * bg.rgb
>+ *
>+ * "Coverage": Blend formula that assumes the pixel color values have not
>+ * been pre-multiplied and will do so when blending them to the background
>+ * color values.
>+ * out.rgb = plane_alpha * fg.alpha * fg.rgb +
>+ * (1 - (plane_alpha * fg.alpha)) * bg.rgb
>+ *
>+ * fg.rgb: Each of the RGB component values from the plane's pixel
>+ * fg.alpha: Alpha component value from the plane's pixel
>+ * bg.rgb: Each of the RGB component values from the background
>+ * plane_alpha: Plane alpha value set by the plane alpha property (if
>+ * applicable).
>+ *
>+ * This property has no effect on formats with no pixel alpha, as fg.alpha
>+ * is assumed to be 1.0. If the plane does not expose the "alpha" property,
>+ * then plane_alpha is assumed to be 1.0, otherwise, it is the value of the
>+ * "alpha" property.
>+ *
I did a little fiddling to make this render nicely in the
documentation output. If you like it, you can apply the hunk below:
-- >8 --
diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
index 714b0602127d..7b5c3307d4c1 100644
--- a/drivers/gpu/drm/drm_blend.c
+++ b/drivers/gpu/drm/drm_blend.c
@@ -113,34 +113,45 @@
* how the pixels from the current plane are composited with the
* background.
*
- * Three alpha blending equations(note that the fg.rgb or bg.rgb notation
- * means each of the R, G or B channels for the foreground and background
- * colors, respectively):
- *
- * "None": Blend formula that ignores the pixel alpha.
- * out.rgb = plane_alpha * fg.rgb + (1 - plane_alpha) * bg.rgb
- *
- * "Pre-multiplied": Blend formula that assumes the pixel color values
- * have been already pre-multiplied with the alpha
- * channel values.
- * out.rgb = plane_alpha * fg.rgb + (1 - (plane_alpha * fg.alpha)) * bg.rgb
- *
- * "Coverage": Blend formula that assumes the pixel color values have not
- * been pre-multiplied and will do so when blending them to the background
- * color values.
- * out.rgb = plane_alpha * fg.alpha * fg.rgb +
- * (1 - (plane_alpha * fg.alpha)) * bg.rgb
- *
- * fg.rgb: Each of the RGB component values from the plane's pixel
- * fg.alpha: Alpha component value from the plane's pixel
- * bg.rgb: Each of the RGB component values from the background
- * plane_alpha: Plane alpha value set by the plane alpha property (if
- * applicable).
- *
- * This property has no effect on formats with no pixel alpha, as fg.alpha
- * is assumed to be 1.0. If the plane does not expose the "alpha" property,
- * then plane_alpha is assumed to be 1.0, otherwise, it is the value of the
- * "alpha" property.
+ * Three alpha blending equations are defined:
+ *
+ * "None":
+ * Blend formula that ignores the pixel alpha::
+ *
+ * out.rgb = plane_alpha * fg.rgb +
+ * (1 - plane_alpha) * bg.rgb
+ *
+ * "Pre-multiplied":
+ * Blend formula that assumes the pixel color values
+ * have been already pre-multiplied with the alpha
+ * channel values::
+ *
+ * out.rgb = plane_alpha * fg.rgb +
+ * (1 - (plane_alpha * fg.alpha)) * bg.rgb
+ *
+ * "Coverage":
+ * Blend formula that assumes the pixel color values have not
+ * been pre-multiplied and will do so when blending them to the
+ * background color values::
+ *
+ * out.rgb = plane_alpha * fg.alpha * fg.rgb +
+ * (1 - (plane_alpha * fg.alpha)) * bg.rgb
+ *
+ * Using the following symbols:
+ *
+ * ``fg.rgb``:
+ * Each of the RGB component values from the plane's pixel
+ * ``fg.alpha``:
+ * Alpha component value from the plane's pixel. If the plane's
+ * pixel format has no alpha component, then this is assumed to be
+ * 1.0. In these cases, this property has no effect, as all three
+ * equations become equivalent.
+ * ``bg.rgb``:
+ * Each of the RGB component values from the background
+ * ``plane_alpha``:
+ * Plane alpha value set by the plane "alpha" property. If the
+ * plane does not expose the "alpha" property, then this is
+ * assumed to be 1.0
*
* Note that all the property extensions described here apply either to the
* plane or the CRTC (e.g. for the background color, which currently is not
-- >8 --
> * Note that all the property extensions described here apply either to the
> * plane or the CRTC (e.g. for the background color, which currently is not
> * exposed and assumed to be black).
>@@ -409,3 +444,78 @@ int drm_atomic_normalize_zpos(struct drm_device *dev,
> return 0;
> }
> EXPORT_SYMBOL(drm_atomic_normalize_zpos);
>+
>+/**
>+ * drm_plane_create_blend_mode_property - create a new blend mode property
>+ * @plane: drm plane
>+ * @supported_modes: bitmask of supported modes, must include
>+ * BIT(DRM_MODE_BLEND_PREMULTI)
>+ *
>+ * This creates a new property describing the blend mode.
>+ *
>+ * The property exposed to userspace is an enumeration property (see
>+ * drm_property_create_enum()) called "pixel blend mode" and has the
>+ * following enumeration values:
>+ *
>+ * "None": Blend formula that ignores the pixel alpha.
>+ *
>+ * "Pre-multiplied": Blend formula that assumes the pixel color values have
>+ * been already pre-multiplied with the alpha channel values.
>+ *
>+ * "Coverage": Blend formula that assumes the pixel color values have not been
>+ * pre-multiplied and will do so when blending them to the
>+ * background color values.
Similar thing here - if you put the descriptions (after the ":") on a
new line, and indent them one more level, then it renders much more
nicely:
* "None":
* Blend formula that ignores the pixel alpha.
Thanks,
-Brian
>+ *
>+ * RETURNS:
>+ * Zero for success or -errno
>+ */
>+int drm_plane_create_blend_mode_property(struct drm_plane *plane,
>+ unsigned int supported_modes)
>+{
>+ struct drm_device *dev = plane->dev;
>+ struct drm_property *prop;
>+ static const struct drm_prop_enum_list props[] = {
>+ { DRM_MODE_BLEND_PIXEL_NONE, "None" },
>+ { DRM_MODE_BLEND_PREMULTI, "Pre-multiplied" },
>+ { DRM_MODE_BLEND_COVERAGE, "Coverage" },
>+ };
>+ unsigned int valid_mode_mask = BIT(DRM_MODE_BLEND_PIXEL_NONE) |
>+ BIT(DRM_MODE_BLEND_PREMULTI) |
>+ BIT(DRM_MODE_BLEND_COVERAGE);
>+ int i, j = 0;
>+
>+ if (WARN_ON((supported_modes & ~valid_mode_mask) ||
>+ ((supported_modes & BIT(DRM_MODE_BLEND_PREMULTI)) == 0)))
>+ return -EINVAL;
>+
>+ prop = drm_property_create(dev, DRM_MODE_PROP_ENUM,
>+ "pixel blend mode",
>+ hweight32(supported_modes));
>+ if (!prop)
>+ return -ENOMEM;
>+
>+ for (i = 0; i < ARRAY_SIZE(props); i++) {
>+ int ret;
>+
>+ if (!(BIT(props[i].type) & supported_modes))
>+ continue;
>+
>+ ret = drm_property_add_enum(prop, j++, props[i].type,
>+ props[i].name);
>+
>+ if (ret) {
>+ drm_property_destroy(dev, prop);
>+
>+ return ret;
>+ }
>+ }
>+
>+ drm_object_attach_property(&plane->base, prop, DRM_MODE_BLEND_PREMULTI);
>+ plane->blend_mode_property = prop;
>+
>+ if (plane->state)
>+ plane->state->pixel_blend_mode = DRM_MODE_BLEND_PREMULTI;
>+
>+ return 0;
>+}
>+EXPORT_SYMBOL(drm_plane_create_blend_mode_property);
>diff --git a/include/drm/drm_blend.h b/include/drm/drm_blend.h
>index 1760602..2966c0d 100644
>--- a/include/drm/drm_blend.h
>+++ b/include/drm/drm_blend.h
>@@ -27,6 +27,10 @@
> #include <linux/ctype.h>
> #include <drm/drm_mode.h>
>
>+#define DRM_MODE_BLEND_PIXEL_NONE 0
>+#define DRM_MODE_BLEND_PREMULTI 1
>+#define DRM_MODE_BLEND_COVERAGE 2
>+
> struct drm_device;
> struct drm_atomic_state;
> struct drm_plane;
>@@ -49,4 +53,6 @@ int drm_plane_create_zpos_immutable_property(struct drm_plane *plane,
> unsigned int zpos);
> int drm_atomic_normalize_zpos(struct drm_device *dev,
> struct drm_atomic_state *state);
>+int drm_plane_create_blend_mode_property(struct drm_plane *plane,
>+ unsigned int supported_modes);
> #endif
>diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
>index f7bf4a4..447ebe7 100644
>--- a/include/drm/drm_plane.h
>+++ b/include/drm/drm_plane.h
>@@ -43,6 +43,8 @@
> * plane (in 16.16)
> * @src_w: width of visible portion of plane (in 16.16)
> * @src_h: height of visible portion of plane (in 16.16)
>+ * @pixel_blend_mode: how the plane's framebuffer alpha channel is used when
>+ * blending with the background colour.
> * @rotation: rotation of the plane
> * @zpos: priority of the given plane on crtc (optional)
> * Note that multiple active planes on the same crtc can have an identical
>@@ -106,6 +108,8 @@ struct drm_plane_state {
> uint32_t src_x, src_y;
> uint32_t src_h, src_w;
>
>+ uint16_t pixel_blend_mode;
>+
> /* Plane rotation */
> unsigned int rotation;
>
>@@ -498,6 +502,7 @@ enum drm_plane_type {
> * @type: type of plane (overlay, primary, cursor)
> * @zpos_property: zpos property for this plane
> * @rotation_property: rotation property for this plane
>+ * @blend_mode_property: blend mode property for this plane
> * @helper_private: mid-layer private data
> */
> struct drm_plane {
>@@ -573,6 +578,7 @@ struct drm_plane {
>
> struct drm_property *zpos_property;
> struct drm_property *rotation_property;
>+ struct drm_property *blend_mode_property;
>
> /**
> * @color_encoding_property:
>--
>1.9.1
>
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