On Wed, May 30, 2018 at 02:27:55PM +0100, Brian Starkey wrote:
> 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@xxxxxxx>
>
> With or without the kerneldoc tweaks I've suggested below, this patch
> is:
>
> Reviewed-by: Brian Starkey <brian.starkey@xxxxxxx>
>
Hi Brian,
Thanks for the patch and comments. Will update a new patchset with this.
Regards,
Lowry
> >---
> >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
> >
--
Regards,
Lowry
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