[PATCH 04/23] drm: Add drm structures for palette color property

[Ville Syrjälä]

On Wed, Sep 16, 2015 at 11:07:01PM +0530, Shashank Sharma wrote:
> From: Kausal Malladi <kausalmalladi at gmail.com>
> 
> This patch adds new structures in DRM layer for Palette color
> correction.These structures will be used by user space agents
> to configure appropriate number of samples and Palette LUT for
> a platform.
> 
> Signed-off-by: Shashank Sharma <shashank.sharma at intel.com>
> Signed-off-by: Kausal Malladi <kausalmalladi at gmail.com>
> ---
>  include/uapi/drm/drm.h | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> index e3c642f..f72b916 100644
> --- a/include/uapi/drm/drm.h
> +++ b/include/uapi/drm/drm.h
> @@ -840,6 +840,33 @@ struct drm_palette_caps {
>  	__u32 num_samples_after_ctm;
>  };
>  
> +struct drm_r32g32b32 {
> +	/*
> +	 * Data is in U8.24 fixed point format.
> +	 * All platforms support values within [0, 1.0] range,
> +	 * for Red, Green and Blue colors.
> +	 */
> +	__u32 r32;
> +	__u32 g32;
> +	__u32 b32;
> +};
> +
> +struct drm_palette {
> +	/* Structure version. Should be 1 currently */
> +	__u32 version;

I don't think we want to version the blobs. For one, we don't have a way
for userspace to ask for a specific version, so the kernel wouldn't know
which version it should return to each client.

If we ever need to come up with new version of a specific blob, I think we
just have to define another property for it. Either that or we'd some kind
of client cap stuff to negotiate the used version between the kernel and
a specific client.

Well, I suppose we migth be able to borrow the "flags+extend at the end"
trick we sometimes use for ioctl parameters to work for blobs too. But I
have a feeling we don't want to go there.

So yeah, I think we should go with the "blob layout is fixed for each
property" approach. Versioning then happens by introducing new versions
of the same property if needed.

> +	/*
> +	 * This has to be a supported value during get call.
> +	 * Feature will be disabled if this is 0 while set
> +	 */
> +	__u32 num_samples;
> +	/*
> +	 * Starting of palette LUT in R32G32B32 format.
> +	 * Each of RGB value is in U8.24 fixed point format.
> +	 * Actual number of samples will depend upon num_samples
> +	 */
> +	struct drm_r32g32b32 lut[0];
> +};
> +
>  /* typedef area */
>  #ifndef __KERNEL__
>  typedef struct drm_clip_rect drm_clip_rect_t;
> -- 
> 1.9.1
> 
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-- 
Ville Syrjälä
Intel OTC