Re: [PATCH 2/8] drm: Add BT.2020 constant luminance enum value for the COLOR_ENCODING property

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Wed, Feb 14, 2018 at 09:23:21PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> BT.2020 specifies two YCbCr<->RGB conversion formulas. The more
> traditional non-constant luminance and a more complicate one constant
> luminance one. Add an enum value for the constant luminance variant
> as well in case someone has hardware supporting it.
> 
> Cc: Harry Wentland <harry.wentland@amd.com>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: Daniel Stone <daniel@fooishbar.org>
> Cc: Russell King - ARM Linux <linux@armlinux.org.uk>
> Cc: Ilia Mirkin <imirkin@alum.mit.edu>
> Cc: Hans Verkuil <hverkuil@xs4all.nl>
> CC: Uma Shankar <uma.shankar@intel.com>
> Cc: Shashank Sharma <shashank.sharma@intel.com>
> Cc: Jyri Sarha <jsarha@ti.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/drm_color_mgmt.c | 1 +
>  include/drm/drm_color_mgmt.h     | 3 ++-
>  2 files changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/drm_color_mgmt.c b/drivers/gpu/drm/drm_color_mgmt.c
> index a84fc861e406..061d342f9d96 100644
> --- a/drivers/gpu/drm/drm_color_mgmt.c
> +++ b/drivers/gpu/drm/drm_color_mgmt.c
> @@ -357,6 +357,7 @@ static const char * const color_encoding_name[] = {
>  	[DRM_COLOR_YCBCR_BT601] = "ITU-R BT.601 YCbCr",
>  	[DRM_COLOR_YCBCR_BT709] = "ITU-R BT.709 YCbCr",
>  	[DRM_COLOR_YCBCR_BT2020] = "ITU-R BT.2020 YCbCr",
> +	[DRM_COLOR_YCBCR_BT2020_CONST] = "ITU-R BT.2020 YCbCr constant luminance",

I just realized that this exceeds the max prop enum name length
of 31 characters. I guess we'll just have to truncate it to something
like "ITU-R BT.2020 YCbCr const". Any better suggestions?

/me goes add some WARN_ON()s for invalid prop/enum names...

>  };
>  
>  static const char * const color_range_name[] = {
> diff --git a/include/drm/drm_color_mgmt.h b/include/drm/drm_color_mgmt.h
> index b3b6d302ca8c..175943c87d5b 100644
> --- a/include/drm/drm_color_mgmt.h
> +++ b/include/drm/drm_color_mgmt.h
> @@ -41,7 +41,8 @@ int drm_mode_crtc_set_gamma_size(struct drm_crtc *crtc,
>  enum drm_color_encoding {
>  	DRM_COLOR_YCBCR_BT601,
>  	DRM_COLOR_YCBCR_BT709,
> -	DRM_COLOR_YCBCR_BT2020,
> +	DRM_COLOR_YCBCR_BT2020, /* non-constant luminance */
> +	DRM_COLOR_YCBCR_BT2020_CONST, /* constant luminance */
>  	DRM_COLOR_ENCODING_MAX,
>  };
>  
> -- 
> 2.13.6

-- 
Ville Syrjälä
Intel OTC
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