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author | Lowry Li <lowry.li@arm.com> | 2018-08-23 16:30:19 +0800 |
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committer | Ayan Kumar Halder <ayan.halder@arm.com> | 2018-08-24 17:31:37 +0100 |
commit | a5ec8332d4280500544e316f76c04a7adc02ce03 (patch) | |
tree | d197ad9eeb065ff018b94b40d144908c7e96dd21 /drivers/gpu/drm/drm_blend.c | |
parent | 06e3c29716d9ba1eedfbd697afddbd7495491b26 (diff) | |
download | linux-a5ec8332d4280500544e316f76c04a7adc02ce03.tar.gz linux-a5ec8332d4280500544e316f76c04a7adc02ce03.tar.bz2 linux-a5ec8332d4280500544e316f76c04a7adc02ce03.zip |
drm: Add per-plane pixel blend mode property
Pixel blend modes represent the alpha blending equation
selection, describing how the pixels from the current
plane are composited with the background.
Adds 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.
Changes since v1:
- Moves the blending equation into the DOC comment
- Refines the comments of drm_plane_create_blend_mode_property to not
enumerate the #defines, but instead the string values
- Uses fg.* instead of pixel.* and plane_alpha instead of plane.alpha
Changes since v2:
- Refines the comments of drm_plane_create_blend_mode_property:
1) Puts the descriptions (after the ":") on a new line
2) Adds explaining why @supported_modes need PREMUL as default
Changes since v3:
- Refines drm_plane_create_blend_mode_property(). drm_property_add_enum()
can calculate the index itself just fine, so no point in having the
caller pass it in.
- Since the current DRM assumption is that alpha is premultiplied
as default, define DRM_MODE_BLEND_PREMULTI as 0 will be better.
- Refines some comments.
Changes since v4:
- Adds comments in drm_blend.h.
- Removes setting default value in drm_plane_create_blend_mode_property()
as it is already in __drm_atomic_helper_plane_reset().
- Fixes to use state->pixel_blend_mode instead of using
plane->state->pixel_blend_mode in reset function.
- Rebases on drm-misc-next.
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Signed-off-by: Lowry Li <lowry.li@arm.com>
Signed-off-by: Ayan Kumar Halder <ayan.halder@arm.com>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/245734/
Diffstat (limited to 'drivers/gpu/drm/drm_blend.c')
-rw-r--r-- | drivers/gpu/drm/drm_blend.c | 123 |
1 files changed, 123 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c index a16a74d7e15e..402b62d3f072 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 +494,80 @@ 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 anything else. + * + * 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; + + 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, 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; + + return 0; +} +EXPORT_SYMBOL(drm_plane_create_blend_mode_property); |