Re: [PATCH 01/19] drm/fourcc: Add a function to tell if the format embeds alpha

[Laurent Pinchart]

Hi Maxime,

Thank you for the patch.

On Tuesday, 9 January 2018 12:56:20 EET Maxime Ripard wrote:
> There's a bunch of drivers that duplicate the same function to know if a
> particular format embeds an alpha component or not.
> 
> Let's create a helper to avoid duplicating that logic.
> 
> Cc: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
> Cc: Eric Anholt <eric@xxxxxxxxxx>
> Cc: Inki Dae <inki.dae@xxxxxxxxxxx>
> Cc: Joonyoung Shim <jy0922.shim@xxxxxxxxxxx>
> Cc: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
> Cc: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> Cc: Mark Yao <mark.yao@xxxxxxxxxxxxxx>
> Cc: Seung-Woo Kim <sw0312.kim@xxxxxxxxxxx>
> Signed-off-by: Maxime Ripard <maxime.ripard@xxxxxxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/drm_fourcc.c | 43 +++++++++++++++++++++++++++++++++++++-
>  include/drm/drm_fourcc.h     |  1 +-
>  2 files changed, 44 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
> index 9c0152df45ad..6e6227d6a46b 100644
> --- a/drivers/gpu/drm/drm_fourcc.c
> +++ b/drivers/gpu/drm/drm_fourcc.c
> @@ -348,3 +348,46 @@ int drm_format_plane_height(int height, uint32_t
> format, int plane) return height / info->vsub;
>  }
>  EXPORT_SYMBOL(drm_format_plane_height);
> +
> +/**
> + * drm_format_has_alpha - get whether the format embeds an alpha component
> + * @format: pixel format (DRM_FORMAT_*)
> + *
> + * Returns:
> + * true if the format embeds an alpha component, false otherwise.
> + */
> +bool drm_format_has_alpha(uint32_t format)
> +{
> +	switch (format) {
> +	case DRM_FORMAT_ARGB4444:
> +	case DRM_FORMAT_ABGR4444:
> +	case DRM_FORMAT_RGBA4444:
> +	case DRM_FORMAT_BGRA4444:
> +	case DRM_FORMAT_ARGB1555:
> +	case DRM_FORMAT_ABGR1555:
> +	case DRM_FORMAT_RGBA5551:
> +	case DRM_FORMAT_BGRA5551:
> +	case DRM_FORMAT_ARGB8888:
> +	case DRM_FORMAT_ABGR8888:
> +	case DRM_FORMAT_RGBA8888:
> +	case DRM_FORMAT_BGRA8888:
> +	case DRM_FORMAT_ARGB2101010:
> +	case DRM_FORMAT_ABGR2101010:
> +	case DRM_FORMAT_RGBA1010102:
> +	case DRM_FORMAT_BGRA1010102:
> +	case DRM_FORMAT_AYUV:
> +	case DRM_FORMAT_XRGB8888_A8:
> +	case DRM_FORMAT_XBGR8888_A8:
> +	case DRM_FORMAT_RGBX8888_A8:
> +	case DRM_FORMAT_BGRX8888_A8:
> +	case DRM_FORMAT_RGB888_A8:
> +	case DRM_FORMAT_BGR888_A8:
> +	case DRM_FORMAT_RGB565_A8:
> +	case DRM_FORMAT_BGR565_A8:
> +		return true;
> +
> +	default:
> +		return false;
> +	}
> +}
> +EXPORT_SYMBOL(drm_format_has_alpha);

How about adding the information to struct drm_format_info instead ? 
drm_format_has_alpha() could then be implemented as

bool drm_format_has_alpha(uint32_t format)
{
	const struct drm_format_info *info;

	info = drm_format_info(format);
	return info ? info->has_alpha : false;
}

although drivers should really use the drm_framebuffer::format field directly 
in most cases, so the helper might not be needed at all.

> diff --git a/include/drm/drm_fourcc.h b/include/drm/drm_fourcc.h
> index 6942e84b6edd..e08fc22c5f78 100644
> --- a/include/drm/drm_fourcc.h
> +++ b/include/drm/drm_fourcc.h
> @@ -69,5 +69,6 @@ int drm_format_vert_chroma_subsampling(uint32_t format);
>  int drm_format_plane_width(int width, uint32_t format, int plane);
>  int drm_format_plane_height(int height, uint32_t format, int plane);
>  const char *drm_get_format_name(uint32_t format, struct drm_format_name_buf
> *buf);
> +bool drm_format_has_alpha(uint32_t format);
> 
>  #endif /* __DRM_FOURCC_H__ */

-- 
Regards,

Laurent Pinchart