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@arm.com --- drivers/gpu/drm/drm_atomic.c | 4 ++ drivers/gpu/drm/drm_atomic_helper.c | 1 + drivers/gpu/drm/drm_blend.c | 126 ++++++++++++++++++++++++++++++++++++ include/drm/drm_blend.h | 6 ++ include/drm/drm_plane.h | 5 ++ 5 files changed, 142 insertions(+)
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c index 07fef42..1d18389 100644 --- a/drivers/gpu/drm/drm_atomic.c +++ b/drivers/gpu/drm/drm_atomic.c @@ -785,6 +785,8 @@ static int drm_atomic_plane_set_property(struct drm_plane *plane, state->src_h = val; } else if (property == plane->alpha_property) { state->alpha = 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; @@ -852,6 +854,8 @@ static int drm_atomic_plane_set_property(struct drm_plane *plane, *val = state->src_h; } else if (property == plane->alpha_property) { *val = state->alpha; + } 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 130da51..7f5d463 100644 --- a/drivers/gpu/drm/drm_atomic_helper.c +++ b/drivers/gpu/drm/drm_atomic_helper.c @@ -3515,6 +3515,7 @@ void drm_atomic_helper_plane_reset(struct drm_plane *plane) /* Reset the alpha value to fully opaque if it matters */ if (plane->alpha_property) plane->state->alpha = plane->alpha_property->values[1]; + 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 a16a74d..ac6f19c 100644 --- a/drivers/gpu/drm/drm_blend.c +++ b/drivers/gpu/drm/drm_blend.c @@ -107,6 +107,52 @@ * 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 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 * exposed and assumed to be black). @@ -448,3 +494,83 @@ 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). Current DRM assumption is + * that alpha is premultiplied, and old userspace can break if + * the property defaults to coverage. + * + * 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. + * + * 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 330c561..28c5076 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; @@ -52,4 +56,6 @@ 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 14b1607..6e2c045 100644 --- a/include/drm/drm_plane.h +++ b/include/drm/drm_plane.h @@ -44,6 +44,8 @@ * @src_w: width of visible portion of plane (in 16.16) * @src_h: height of visible portion of plane (in 16.16) * @alpha: opacity of the plane + * @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 @@ -116,6 +118,7 @@ struct drm_plane_state {
/* Plane opacity */ u16 alpha; + uint16_t pixel_blend_mode;
/* Plane rotation */ unsigned int rotation; @@ -513,6 +516,7 @@ enum drm_plane_type { * @alpha_property: alpha property for this plane * @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 { @@ -589,6 +593,7 @@ struct drm_plane { struct drm_property *alpha_property; struct drm_property *zpos_property; struct drm_property *rotation_property; + struct drm_property *blend_mode_property;
/** * @color_encoding_property: