On Wed, Aug 22, 2018 at 03:27:44PM +0200, Maarten Lankhorst wrote:
> Op 15-08-18 om 08:35 schreef Lowry Li:
> > 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.
> >
> > Signed-off-by: Lowry Li <[email protected]>
> > ---
> > 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 | 2 +
> > 5 files changed, 139 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> > index 3eb061e..d0478ab 100644
> > --- a/drivers/gpu/drm/drm_atomic.c
> > +++ b/drivers/gpu/drm/drm_atomic.c
> > @@ -895,6 +895,8 @@ 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)) {
> > DRM_DEBUG_ATOMIC("[PLANE:%d:%s] bad rotation bitmask:
> > 0x%llx\n",
> > @@ -968,6 +970,8 @@ 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 6dd5036..563af09 100644
> > --- a/drivers/gpu/drm/drm_atomic_helper.c
> > +++ b/drivers/gpu/drm/drm_atomic_helper.c
> > @@ -3569,6 +3569,7 @@ void __drm_atomic_helper_plane_reset(struct drm_plane
> > *plane,
> > /* Reset the alpha value to fully opaque if it matters */
> > if (plane->alpha_property)
> > state->alpha = plane->alpha_property->values[1];
> > + plane->state->pixel_blend_mode = DRM_MODE_BLEND_PREMULTI;
> >
> > plane->state = state;
> > }
> > diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
> > index a16a74d..24016c9 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 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);
> Do we still care about !atomic kernel drivers?
Hi Maarten,
Thanks for your comments. We don't need to care about this. And
DRM_MODE_BLEND_PREMULTI is zero as default.
> > + plane->blend_mode_property = prop;
> > +
> > + if (plane->state)
> > + plane->state->pixel_blend_mode = DRM_MODE_BLEND_PREMULTI;
>
> Is this still needed with the hunk in __drm_atomic_helper_plane_reset() ? I
> would just remove it.
Totally agree. Will remove this. Thanks a lot:)
> > +
> > + 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..88bdfec 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_PREMULTI 0
> > +#define DRM_MODE_BLEND_COVERAGE 1
> > +#define DRM_MODE_BLEND_PIXEL_NONE 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 8a152dc..c52614a 100644
> > --- a/include/drm/drm_plane.h
> > +++ b/include/drm/drm_plane.h
> > @@ -117,6 +117,7 @@ struct drm_plane_state {
> > * details.
> > */
> > u16 alpha;
> > + uint16_t pixel_blend_mode;
> >
> > /**
> > * @rotation:
> > @@ -659,6 +660,7 @@ struct drm_plane {
> > * drm_plane_create_rotation_property().
> > */
> > struct drm_property *rotation_property;
> > + struct drm_property *blend_mode_property;
> >
> > /**
> > * @color_encoding_property:
>
> These need to be documented.
Yes, will add this. Thanks.
> With those changes:
>
> Reviewed-by: Maarten Lankhorst <[email protected]>
>
> ~Maarten
--
Regards,
Lowry
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