Re: [Intel-gfx] [PATCH 1/4] drm: Added plane alpha and color blending property

[Damien Lespiau <damien.lespiau@intel.com>]

On Sat, Mar 08, 2014 at 01:51:16PM +0530, sagar.a.kamble@intel.com wrote:
> From: Sagar Kamble <sagar.a.kamble@intel.com>
> 
> This patch creates a generic blending enum property.
> Drivers may support subset of these values.
> 
> Cc: airlied@linux.ie
> Cc: dri-devel@lists.freedesktop.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Sagar Kamble <sagar.a.kamble@intel.com>
> ---
>  drivers/gpu/drm/drm_crtc.c | 33 +++++++++++++++++++++++++++++++++
>  include/drm/drm_crtc.h     | 25 +++++++++++++++++++++++++
>  2 files changed, 58 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
> index 4e43fc2..15281a3 100644
> --- a/drivers/gpu/drm/drm_crtc.c
> +++ b/drivers/gpu/drm/drm_crtc.c
> @@ -4147,3 +4147,36 @@ void drm_mode_config_cleanup(struct drm_device *dev)
>  	idr_destroy(&dev->mode_config.crtc_idr);
>  }
>  EXPORT_SYMBOL(drm_mode_config_cleanup);
> +
> +struct drm_property *drm_mode_create_blend_property(struct drm_device *dev,
> +				unsigned int supported_factors)
> +{
> +	static const struct drm_prop_enum_list props[] = {
> +		{ DRM_BLEND_NONE,   			"none" },
> +		{ DRM_BLEND_ZERO,  			"zero" },
> +		{ DRM_BLEND_ONE, 			"one" },
> +		{ DRM_BLEND_SRC_COLOR, 			"src-color" },
> +		{ DRM_BLEND_ONE_MINUS_SRC_COLOR,  	"one-minus-src-color" },
> +		{ DRM_BLEND_DST_COLOR, 			"dst-color" },
> +		{ DRM_BLEND_ONE_MINUS_DST_COLOR,  	"one-minus-dst-color" },
> +		{ DRM_BLEND_SRC_ALPHA, 			"src-alpha" },
> +		{ DRM_BLEND_ONE_MINUS_SRC_ALPHA, 	"one-minus-src-alpha" },
> +		{ DRM_BLEND_DST_ALPHA, 			"dst-alpha" },
> +		{ DRM_BLEND_ONE_MINUS_DST_ALPHA, 	"one-minus-dst-alpha" },
> +		{ DRM_BLEND_CONSTANT_COLOR, 		"constant-color" },
> +		{ DRM_BLEND_ONE_MINUS_CONSTANT_COLOR, 	"one-minus-constant-color" },
> +		{ DRM_BLEND_CONSTANT_ALPHA, 		"constant-alpha" },
> +		{ DRM_BLEND_ONE_MINUS_CONSTANT_ALPHA, 	"one-minus-constant-alpha" },
> +		{ DRM_BLEND_SRC_ALPHA_SATURATE, 	"alpha-saturate" },
> +		{ DRM_BLEND_SRC1_COLOR, 		"src1-color" },
> +		{ DRM_BLEND_ONE_MINUS_SRC1_COLOR, 	"one-minus-src1-color" },
> +		{ DRM_BLEND_SRC1_ALPHA, 		"src1-alpha" },
> +		{ DRM_BLEND_ONE_MINUS_SRC1_ALPHA, 	"one-minus-src1-alpha" },
> +		{ DRM_BLEND_PREMULTIPLIED_ALPHA, 	"pre-multiplied-alpha" }
> +	};

Another few notes:

- You seem to assume that there's a need for DRM_BLEND_NONE, what would it
do? The property should default to DRM_BLEND_SRC_COLOR ie "Take the
color from this plane for the blending".

- There's no need to expose SRC1 variants, this was done in GL to expose a
second color the fragment shader can output, not applicable here.

-- 
Damien