Re: [PATCH RFC v4 2/7] drm: Introduce pixel_source DRM plane property
From: Sebastian Wick
Date: Fri Jun 30 2023 - 10:44:54 EST
On Fri, Jun 30, 2023 at 2:26 AM Jessica Zhang <quic_jesszhan@xxxxxxxxxxx> wrote:
>
> Add support for pixel_source property to drm_plane and related
> documentation.
>
> This enum property will allow user to specify a pixel source for the
> plane. Possible pixel sources will be defined in the
> drm_plane_pixel_source enum.
>
> The current possible pixel sources are DRM_PLANE_PIXEL_SOURCE_FB and
> DRM_PLANE_PIXEL_SOURCE_COLOR. The default value is *_SOURCE_FB.
>
> Signed-off-by: Jessica Zhang <quic_jesszhan@xxxxxxxxxxx>
> ---
> drivers/gpu/drm/drm_atomic_state_helper.c | 1 +
> drivers/gpu/drm/drm_atomic_uapi.c | 4 ++
> drivers/gpu/drm/drm_blend.c | 81 +++++++++++++++++++++++++++++++
> include/drm/drm_blend.h | 2 +
> include/drm/drm_plane.h | 21 ++++++++
> 5 files changed, 109 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_atomic_state_helper.c b/drivers/gpu/drm/drm_atomic_state_helper.c
> index fe14be2bd2b2..86fb876efbe6 100644
> --- a/drivers/gpu/drm/drm_atomic_state_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_state_helper.c
> @@ -252,6 +252,7 @@ void __drm_atomic_helper_plane_state_reset(struct drm_plane_state *plane_state,
>
> plane_state->alpha = DRM_BLEND_ALPHA_OPAQUE;
> plane_state->pixel_blend_mode = DRM_MODE_BLEND_PREMULTI;
> + plane_state->pixel_source = DRM_PLANE_PIXEL_SOURCE_FB;
>
> if (plane_state->solid_fill_blob) {
> drm_property_blob_put(plane_state->solid_fill_blob);
> diff --git a/drivers/gpu/drm/drm_atomic_uapi.c b/drivers/gpu/drm/drm_atomic_uapi.c
> index a28b4ee79444..6e59c21af66b 100644
> --- a/drivers/gpu/drm/drm_atomic_uapi.c
> +++ b/drivers/gpu/drm/drm_atomic_uapi.c
> @@ -596,6 +596,8 @@ static int drm_atomic_plane_set_property(struct drm_plane *plane,
> drm_property_blob_put(solid_fill);
>
> return ret;
> + } else if (property == plane->pixel_source_property) {
> + state->pixel_source = val;
> } else if (property == plane->alpha_property) {
> state->alpha = val;
> } else if (property == plane->blend_mode_property) {
> @@ -671,6 +673,8 @@ drm_atomic_plane_get_property(struct drm_plane *plane,
> } else if (property == plane->solid_fill_property) {
> *val = state->solid_fill_blob ?
> state->solid_fill_blob->base.id : 0;
> + } else if (property == plane->pixel_source_property) {
> + *val = state->pixel_source;
> } else if (property == plane->alpha_property) {
> *val = state->alpha;
> } else if (property == plane->blend_mode_property) {
> diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
> index 38c3c5d6453a..8c100a957ee2 100644
> --- a/drivers/gpu/drm/drm_blend.c
> +++ b/drivers/gpu/drm/drm_blend.c
> @@ -189,6 +189,18 @@
> * solid_fill is set up with drm_plane_create_solid_fill_property(). It
> * contains pixel data that drivers can use to fill a plane.
> *
> + * pixel_source:
> + * pixel_source is set up with drm_plane_create_pixel_source_property().
> + * It is used to toggle the source of pixel data for the plane.
> + *
> + * Possible values:
> + *
> + * "FB":
> + * Framebuffer source
> + *
> + * "COLOR":
> + * solid_fill source
> + *
> * 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).
> @@ -648,3 +660,72 @@ int drm_plane_create_solid_fill_property(struct drm_plane *plane)
> return 0;
> }
> EXPORT_SYMBOL(drm_plane_create_solid_fill_property);
> +
> +/**
> + * drm_plane_create_pixel_source_property - create a new pixel source property
> + * @plane: drm plane
> + * @supported_sources: bitmask of supported pixel_sources for the driver (NOT
> + * including DRM_PLANE_PIXEL_SOURCE_FB, as it will be supported
> + * by default).
> + *
> + * This creates a new property describing the current source of pixel data for the
> + * plane.
> + *
> + * The property is exposed to userspace as an enumeration property called
> + * "pixel_source" and has the following enumeration values:
> + *
> + * "FB":
> + * Framebuffer pixel source
> + *
> + * "COLOR":
> + * Solid fill color pixel source
Can we add a "NONE" value?
I know it has been discussed earlier if we *need* this and I don't
think we do. I just think it would be better API design to disable
planes this way than having to know that a framebuffer pixel source
with a NULL framebuffer disables the plane. Obviously also keep the
old behavior for backwards compatibility.
> + *
> + * Returns:
> + * Zero on success, negative errno on failure.
> + */
> +int drm_plane_create_pixel_source_property(struct drm_plane *plane,
> + unsigned int supported_sources)
> +{
> + struct drm_device *dev = plane->dev;
> + struct drm_property *prop;
> + const struct drm_prop_enum_list enum_list[] = {
> + { DRM_PLANE_PIXEL_SOURCE_FB, "FB" },
> + { DRM_PLANE_PIXEL_SOURCE_COLOR, "COLOR" },
> + };
> + unsigned int valid_source_mask = BIT(DRM_PLANE_PIXEL_SOURCE_FB) |
> + BIT(DRM_PLANE_PIXEL_SOURCE_COLOR);
> + int i;
> +
> + /* FB is supported by default */
> + supported_sources |= BIT(DRM_PLANE_PIXEL_SOURCE_FB);
> +
> + if (WARN_ON(supported_sources & ~valid_source_mask))
> + return -EINVAL;
> +
> + prop = drm_property_create(dev, DRM_MODE_PROP_ENUM, "pixel_source",
> + hweight32(supported_sources));
> +
> + if (!prop)
> + return -ENOMEM;
> +
> + for (i = 0; i < ARRAY_SIZE(enum_list); i++) {
> + int ret;
> +
> + if (!(BIT(enum_list[i].type) & supported_sources))
> + continue;
> +
> + ret = drm_property_add_enum(prop, enum_list[i].type, enum_list[i].name);
> +
> + if (ret) {
> + drm_property_destroy(dev, prop);
> +
> + return ret;
> + }
> + }
> +
> + drm_object_attach_property(&plane->base, prop, DRM_PLANE_PIXEL_SOURCE_FB);
> + plane->pixel_source_property = prop;
> +
> + return 0;
> +}
> +EXPORT_SYMBOL(drm_plane_create_pixel_source_property);
> diff --git a/include/drm/drm_blend.h b/include/drm/drm_blend.h
> index 0338a860b9c8..31af7cfa5b1b 100644
> --- a/include/drm/drm_blend.h
> +++ b/include/drm/drm_blend.h
> @@ -59,4 +59,6 @@ int drm_atomic_normalize_zpos(struct drm_device *dev,
> int drm_plane_create_blend_mode_property(struct drm_plane *plane,
> unsigned int supported_modes);
> int drm_plane_create_solid_fill_property(struct drm_plane *plane);
> +int drm_plane_create_pixel_source_property(struct drm_plane *plane,
> + unsigned int supported_sources);
> #endif
> diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
> index f6ab313cb83e..73fb6cf8a5d9 100644
> --- a/include/drm/drm_plane.h
> +++ b/include/drm/drm_plane.h
> @@ -59,6 +59,12 @@ struct drm_solid_fill {
> uint32_t b;
> };
>
> +enum drm_plane_pixel_source {
> + DRM_PLANE_PIXEL_SOURCE_FB,
> + DRM_PLANE_PIXEL_SOURCE_COLOR,
> + DRM_PLANE_PIXEL_SOURCE_MAX
> +};
> +
> /**
> * struct drm_plane_state - mutable plane state
> *
> @@ -152,6 +158,14 @@ struct drm_plane_state {
> */
> struct drm_solid_fill solid_fill;
>
> + /*
> + * @pixel_source:
> + *
> + * Source of pixel information for the plane. See
> + * drm_plane_create_pixel_source_property() for more details.
> + */
> + enum drm_plane_pixel_source pixel_source;
> +
> /**
> * @alpha:
> * Opacity of the plane with 0 as completely transparent and 0xffff as
> @@ -742,6 +756,13 @@ struct drm_plane {
> */
> struct drm_property *solid_fill_property;
>
> + /*
> + * @pixel_source_property:
> + * Optional pixel_source property for this plane. See
> + * drm_plane_create_pixel_source_property().
> + */
> + struct drm_property *pixel_source_property;
> +
> /**
> * @alpha_property:
> * Optional alpha property for this plane. See
>
> --
> 2.41.0
>