Re: [PATCH 1/4] drm: Add Y210, Y212, Y216 format definitions and fourcc

[Alexandru-Cosmin Gheorghe <Alexandru-Cosmin.Gheorghe@arm.com>]

Hi Swati,

On Mon, Aug 27, 2018 at 12:17:45PM +0530, Swati Sharma wrote:
> From: Vidya Srinivas <vidya.srinivas@intel.com>
> 
> The following pixel formats are packed format that follows 4:2:2
> chroma sampling. For memory represenation each component is
> allocated 16 bits each. Thus each pixel occupies a DWORD.
> 
> Y210: 	Valid data occupies MSB 10 bits.
> 	LSB 6 bits are filled with zeroes.
> Y212: 	Valid data occupies MSB 12 bits.
> 	LSB 4 bits are filled with zeroes.
> Y216: 	Valid data occupies 16 bits,
> 	doesn't require any padding bits.
> 
> First 16 bits stores the Y value and the next 16 bits stores one
> of the chroma samples alternatively. The first luma sample will
> be accompanied by first U sample and second luma sample is
> accompanied by the first V sample.
> 
> Signed-off-by: Swati Sharma <swati2.sharma@intel.com>
> Signed-off-by: Vidya Srinivas <vidya.srinivas@intel.com>
> ---
>  drivers/gpu/drm/drm_fourcc.c  | 3 +++
>  include/uapi/drm/drm_fourcc.h | 4 ++++
>  2 files changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
> index 35c1e27..4bf04a5 100644
> --- a/drivers/gpu/drm/drm_fourcc.c
> +++ b/drivers/gpu/drm/drm_fourcc.c
> @@ -173,6 +173,9 @@ const struct drm_format_info *__drm_format_info(u32 format)
>  		{ .format = DRM_FORMAT_UYVY,		.depth = 0,  .num_planes = 1, .cpp = { 2, 0, 0 }, .hsub = 2, .vsub = 1, .is_yuv = true },
>  		{ .format = DRM_FORMAT_VYUY,		.depth = 0,  .num_planes = 1, .cpp = { 2, 0, 0 }, .hsub = 2, .vsub = 1, .is_yuv = true },
>  		{ .format = DRM_FORMAT_AYUV,		.depth = 0,  .num_planes = 1, .cpp = { 4, 0, 0 }, .hsub = 1, .vsub = 1, .has_alpha = true, .is_yuv = true },
> +		{ .format = DRM_FORMAT_Y210,            .depth = 0,  .num_planes = 1, .cpp = { 8, 0, 0 }, .hsub = 2, .vsub = 1 },
> +		{ .format = DRM_FORMAT_Y212,            .depth = 0,  .num_planes = 1, .cpp = { 8, 0, 0 }, .hsub = 2, .vsub = 1 },
> +		{ .format = DRM_FORMAT_Y216,            .depth = 0,  .num_planes = 1, .cpp = { 8, 0, 0 }, .hsub = 2, .vsub = 1 },
>  	};
>  
>  	unsigned int i;
> diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
> index 2ed46e9..6a03e6d 100644
> --- a/include/uapi/drm/drm_fourcc.h
> +++ b/include/uapi/drm/drm_fourcc.h
> @@ -149,6 +149,10 @@
>  
>  #define DRM_FORMAT_AYUV		fourcc_code('A', 'Y', 'U', 'V') /* [31:0] A:Y:Cb:Cr 8:8:8:8 little endian */
>  
> +#define DRM_FORMAT_Y210         fourcc_code('Y', '2', '1', '0') /* [63:0] Y0:Cb0:Y1:Cr1 10:10:10:10 little endian */
> +#define DRM_FORMAT_Y212         fourcc_code('Y', '2', '1', '2') /* [63:0] Y0:Cb0:Y1:Cr1 12:12:12:12 little endian */
> +#define DRM_FORMAT_Y216         fourcc_code('Y', '2', '1', '6') /* [63:0] Y0:Cb0:Y1:Cr1 16:16:16:16 little endian */

I don't think this comments reflect very well the actual layout of the
color planes, I think you need to describe the padding as well.

Just looking at the comments without reading the commit message you
could easily assume that the padding happens is in the [63:40] bits.


> +
>  /*
>   * 2 plane RGB + A
>   * index 0 = RGB plane, same format as the corresponding non _A8 format has
> -- 
> 1.9.1
> 
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-- 
Cheers,
Alex G
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