[PATCH v3 1/8] drm/blend: Add a generic alpha property

[laurent.pinchart@ideasonboard.com (Laurent Pinchart)]

Hi Maxime,

Thank you for the patch.

On Friday, 16 February 2018 19:39:29 EET Maxime Ripard wrote:
> Some drivers duplicate the logic to create a property to store a per-plane
> alpha.
> 
> This is especially useful if we ever want to support extra protocols for
> Wayland like:
> https://lists.freedesktop.org/archives/wayland-devel/2017-August/034741.html
> 
> Let's create a helper in order to move that to the core.
> 
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>
> Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
> ---
>  Documentation/gpu/kms-properties.csv |  2 +-
>  drivers/gpu/drm/drm_atomic.c         |  4 ++++-
>  drivers/gpu/drm/drm_atomic_helper.c  |  4 ++++-
>  drivers/gpu/drm/drm_blend.c          | 32 +++++++++++++++++++++++++++++-
>  include/drm/drm_blend.h              |  1 +-
>  include/drm/drm_plane.h              |  6 +++++-
>  6 files changed, 48 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/gpu/kms-properties.csv
> b/Documentation/gpu/kms-properties.csv index 927b65e14219..25ad3503d663
> 100644
> --- a/Documentation/gpu/kms-properties.csv
> +++ b/Documentation/gpu/kms-properties.csv
> @@ -99,5 +99,5 @@ radeon,DVI-I,?coherent?,RANGE,"Min=0, Max=1",Connector,TBD
> ,,"""underscan vborder""",RANGE,"Min=0, Max=128",Connector,TBD
>  ,Audio,?audio?,ENUM,"{ ""off"", ""on"", ""auto"" }",Connector,TBD
>  ,FMT Dithering,?dither?,ENUM,"{ ""off"", ""on"" }",Connector,TBD
> -rcar-du,Generic,"""alpha""",RANGE,"Min=0, Max=255",Plane,TBD
> +,,"""alpha""",RANGE,"Min=0, Max=Driver dependant",Plane,Opacity of the
> plane from transparent (0) to fully opaque (MAX). If this property is set
> to a value different than max, and that the pixel will define an alpha
> component, the property will have precendance and the pixel value will be
> ignored. The alpha value is represented as straight alpha, ie the colors
> haven't been pre-adjusted for their opacity by multiplication. Therefore,
> the equation to get a color value for one pixel, assuming two planes A and
> B, will be (color_a * alpha_a + color_b * alpha_b * (MAX - alpha_a) / MAX)
> / (alpha_a + alpha_b * (MAX - alpha_a) / MAX)
> ,,"""colorkey""",RANGE,"Min=0, Max=0x01ffffff",Plane,TBD
> diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
> index 7d9ad20040a1..3defc56a1ef2 100644
> --- a/drivers/gpu/drm/drm_atomic.c
> +++ b/drivers/gpu/drm/drm_atomic.c
> @@ -753,6 +753,8 @@ 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->alpha_property) {
> +		state->alpha = val;
>  	} else if (property == plane->rotation_property) {
>  		if (!is_power_of_2(val & DRM_MODE_ROTATE_MASK))
>  			return -EINVAL;
> @@ -814,6 +816,8 @@ drm_atomic_plane_get_property(struct drm_plane *plane,
>  		*val = state->src_w;
>  	} else if (property == config->prop_src_h) {
>  		*val = state->src_h;
> +	} else if (property == plane->alpha_property) {
> +		*val = state->alpha;
>  	} 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 ae3cbfe9e01c..2b88f593aab4
> 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -3482,6 +3482,10 @@ void drm_atomic_helper_plane_reset(struct drm_plane
> *plane) if (plane->state) {
>  		plane->state->plane = plane;
>  		plane->state->rotation = DRM_MODE_ROTATE_0;
> +
> +		/* Reset the alpha value to fully opaque if it matters */
> +		if (plane->alpha_property)
> +			plane->state->alpha = plane->alpha_property->values[1];
>  	}
>  }
>  EXPORT_SYMBOL(drm_atomic_helper_plane_reset);
> diff --git a/drivers/gpu/drm/drm_blend.c b/drivers/gpu/drm/drm_blend.c
> index 4c62dff14893..a5dea7cbed2c 100644
> --- a/drivers/gpu/drm/drm_blend.c
> +++ b/drivers/gpu/drm/drm_blend.c
> @@ -104,6 +104,38 @@
>   */
> 
>  /**
> + * drm_plane_create_alpha_property - create a new alpha property
> + * @plane: drm plane
> + * @max_alpha: maximum value of alpha
> + *
> + * This function initializes a generic, mutable, alpha property and
> + * enables support for it in the DRM core.

s/initializes/creates/

I would also mention that it attaches the property to the plane.

> + * The alpha property will be allowed to be within the bounds of 0
> + * (transparent) to @max_alpha (opaque)

s/$/./

> + *
> + * Returns:
> + * 0 on success, negative error code on failure.
> + */
> +int drm_plane_create_alpha_property(struct drm_plane *plane, u16 max_alpha)
> +{
> +	struct drm_property *prop;
> +
> +	prop = drm_property_create_range(plane->dev, 0, "alpha", 0, max_alpha);
> +	if (!prop)
> +		return -ENOMEM;
> +
> +	drm_object_attach_property(&plane->base, prop, max_alpha);
> +	plane->alpha_property = prop;
> +
> +	if (plane->state)
> +		plane->state->alpha = max_alpha;
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(drm_plane_create_alpha_property);
> +
> +/**
>   * drm_plane_create_rotation_property - create a new rotation property
>   * @plane: drm plane
>   * @rotation: initial value of the rotation property
> diff --git a/include/drm/drm_blend.h b/include/drm/drm_blend.h
> index 17606026590b..e5affba6ebde 100644
> --- a/include/drm/drm_blend.h
> +++ b/include/drm/drm_blend.h
> @@ -36,6 +36,7 @@ static inline bool drm_rotation_90_or_270(unsigned int
> rotation) return rotation & (DRM_MODE_ROTATE_90 | DRM_MODE_ROTATE_270);
>  }
> 
> +int drm_plane_create_alpha_property(struct drm_plane *plane, u16 alpha);
>  int drm_plane_create_rotation_property(struct drm_plane *plane,
>  				       unsigned int rotation,
>  				       unsigned int supported_rotations);
> diff --git a/include/drm/drm_plane.h b/include/drm/drm_plane.h
> index 8185e3468a23..5a6f29524f12 100644
> --- a/include/drm/drm_plane.h
> +++ b/include/drm/drm_plane.h
> @@ -42,6 +42,7 @@ struct drm_modeset_acquire_ctx;
>   *	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)
> + * @alpha: opacity of the plane
>   * @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
> @@ -105,6 +106,9 @@ struct drm_plane_state {
>  	uint32_t src_x, src_y;
>  	uint32_t src_h, src_w;
> 
> +	/* Plane opacity */
> +	u8 alpha;
> +
>  	/* Plane rotation */
>  	unsigned int rotation;
> 
> @@ -481,6 +485,7 @@ enum drm_plane_type {
>   * @funcs: helper functions
>   * @properties: property tracking for this plane
>   * @type: type of plane (overlay, primary, cursor)
> + * @alpha_property: alpha property for this plane
>   * @zpos_property: zpos property for this plane
>   * @rotation_property: rotation property for this plane
>   * @helper_private: mid-layer private data
> @@ -556,6 +561,7 @@ struct drm_plane {
>  	 */
>  	struct drm_plane_state *state;
> 
> +	struct drm_property *alpha_property;
>  	struct drm_property *zpos_property;
>  	struct drm_property *rotation_property;
>  };

-- 
Regards,

Laurent Pinchart