[PATCH] drm/color: document NULL values and default settings better

[Lionel Landwerlin]

Sorry for missing this.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin at intel.com>

On 26/09/16 10:04, Daniel Vetter wrote:
> Brought up in a discussion for enabling gamma on fsl-dcu.
>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: Meng Yi <meng.yi at nxp.com>
> Cc: Lionel Landwerlin <lionel.g.landwerlin at intel.com>
> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> ---
>   drivers/gpu/drm/drm_color_mgmt.c | 12 ++++++++++++
>   1 file changed, 12 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_color_mgmt.c 
> b/drivers/gpu/drm/drm_color_mgmt.c
> index d28ffdd2b929..6543ebde501a 100644
> --- a/drivers/gpu/drm/drm_color_mgmt.c
> +++ b/drivers/gpu/drm/drm_color_mgmt.c
> @@ -41,6 +41,10 @@
>    *  nor use all the elements of the LUT (for example the hardware might
>    *  choose to interpolate between LUT[0] and LUT[4]).
>    *
> + *   Setting this to NULL (blob property value set to 0) means a
> + *   linear/pass-thru gamma table should be used. This is generally the
> + *   driver boot-up state too.
> + *
>    * “DEGAMMA_LUT_SIZE”:
>    *  Unsinged range property to give the size of the lookup table to be set
>    *  on the DEGAMMA_LUT property (the size depends on the underlying
> @@ -54,6 +58,10 @@
>    *  lookup through the gamma LUT. The data is interpreted as a struct
>    *  &drm_color_ctm.
>    *
> + *   Setting this to NULL (blob property value set to 0) means a
> + *   unit/pass-thru matrix should be used. This is generally the driver
> + *   boot-up state too.
> + *
>    * “GAMMA_LUT”:
>    *  Blob property to set the gamma lookup table (LUT) mapping pixel data
>    *  after the transformation matrix to data sent to the connector. The
> @@ -62,6 +70,10 @@
>    *  nor use all the elements of the LUT (for example the hardware might
>    *  choose to interpolate between LUT[0] and LUT[4]).
>    *
> + *   Setting this to NULL (blob property value set to 0) means a
> + *   linear/pass-thru gamma table should be used. This is generally the
> + *   driver boot-up state too.
> + *
>    * “GAMMA_LUT_SIZE”:
>    *  Unsigned range property to give the size of the lookup table to be set
>    *  on the GAMMA_LUT property (the size depends on the underlying hardware).