[PATCH] drm: drm_fourcc: add NV15, Q410, Q401 YUV formats

[Brian Starkey]

Hi Ben,

On Wed, May 06, 2020 at 03:41:26PM +0100, Ben Davis wrote:
> Hi all, any feedback on this patch?
> Thanks, Ben
> On Wed, Apr 22, 2020 at 12:13:49PM +0100, Ben Davis wrote:
> > DRM_FORMAT_NV15 is a 2 plane format suitable for linear and 16x16
> > block-linear memory layouts. The format is similar to P010 with 4:2:0
> > sub-sampling but has no padding between components. Instead, luminance
> > and chrominance samples are grouped into 4s so that each group is packed
> > into an integer number of bytes:
> > 
> > YYYY = UVUV = 4 * 10 bits = 40 bits = 5 bytes
> > 
> > The '15' suffix refers to the optimum effective bits per pixel which is
> > achieved when the total number of luminance samples is a multiple of 8.
> > 
> > Q410 and Q401 are both 3 plane non-subsampled formats with 16 bits per
> > component, but only 10 bits are used and 6 are padded. 'Q' is chosen
> > as the first letter to denote 3 plane YUV444, (and is the next letter
> > along from P which is usually 2 plane).
> > 
> > Signed-off-by: Ben Davis <ben.davis at arm.com>

The descriptions match my understanding of the formats and the
format_info struct, so feel free to add my r-b:

Reviewed-by: Brian Starkey <brian.starkey at arm.com>

Can anyone else pass comment on the approach and/or naming? I feel
like we should have some non-Arm eyes on this before we merge it.

Thanks,
-Brian

> > ---
> >  drivers/gpu/drm/drm_fourcc.c  | 12 ++++++++++++
> >  include/uapi/drm/drm_fourcc.h | 24 ++++++++++++++++++++++++
> >  2 files changed, 36 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
> > index b234bfaeda06..0c0a65481afd 100644
> > --- a/drivers/gpu/drm/drm_fourcc.c
> > +++ b/drivers/gpu/drm/drm_fourcc.c
> > @@ -274,6 +274,18 @@ const struct drm_format_info *__drm_format_info(u32 format)
> >  		{ .format = DRM_FORMAT_YUV420_10BIT,    .depth = 0,
> >  		  .num_planes = 1, .cpp = { 0, 0, 0 }, .hsub = 2, .vsub = 2,
> >  		  .is_yuv = true },
> > +		{ .format = DRM_FORMAT_NV15,		.depth = 0,
> > +		  .num_planes = 2, .char_per_block = { 5, 5, 0 },
> > +		  .block_w = { 4, 4, 0 }, .block_h = { 1, 1, 0 }, .hsub = 2,
> > +		  .vsub = 2, .is_yuv = true },
> > +		{ .format = DRM_FORMAT_Q410,		.depth = 0,
> > +		  .num_planes = 3, .char_per_block = { 2, 2, 2 },
> > +		  .block_w = { 1, 1, 1 }, .block_h = { 1, 1, 1 }, .hsub = 0,
> > +		  .vsub = 0, .is_yuv = true },
> > +		{ .format = DRM_FORMAT_Q401,		.depth = 0,
> > +		  .num_planes = 3, .char_per_block = { 2, 2, 2 },
> > +		  .block_w = { 1, 1, 1 }, .block_h = { 1, 1, 1 }, .hsub = 0,
> > +		  .vsub = 0, .is_yuv = true },
> >  	};
> >  
> >  	unsigned int i;
> > diff --git a/include/uapi/drm/drm_fourcc.h b/include/uapi/drm/drm_fourcc.h
> > index 8bc0b31597d8..232b9ad3534d 100644
> > --- a/include/uapi/drm/drm_fourcc.h
> > +++ b/include/uapi/drm/drm_fourcc.h
> > @@ -236,6 +236,12 @@ extern "C" {
> >  #define DRM_FORMAT_NV61		fourcc_code('N', 'V', '6', '1') /* 2x1 subsampled Cb:Cr plane */
> >  #define DRM_FORMAT_NV24		fourcc_code('N', 'V', '2', '4') /* non-subsampled Cr:Cb plane */
> >  #define DRM_FORMAT_NV42		fourcc_code('N', 'V', '4', '2') /* non-subsampled Cb:Cr plane */
> > +/*
> > + * 2 plane YCbCr
> > + * index 0 = Y plane, [39:0] Y3:Y2:Y1:Y0 little endian
> > + * index 1 = Cr:Cb plane, [39:0] Cr1:Cb1:Cr0:Cb0 little endian
> > + */
> > +#define DRM_FORMAT_NV15		fourcc_code('N', 'V', '1', '5') /* 2x2 subsampled Cr:Cb plane */
> >  
> >  /*
> >   * 2 plane YCbCr MSB aligned
> > @@ -265,6 +271,24 @@ extern "C" {
> >   */
> >  #define DRM_FORMAT_P016		fourcc_code('P', '0', '1', '6') /* 2x2 subsampled Cr:Cb plane 16 bits per channel */
> >  
> > +
> > +/* 3 plane non-subsampled (444) YCbCr
> > + * 16 bits per component, but only 10 bits are used and 6 bits are padded
> > + * index 0: Y plane, [15:0] Y:x [10:6] little endian
> > + * index 1: Cb plane, [15:0] Cb:x [10:6] little endian
> > + * index 2: Cr plane, [15:0] Cr:x [10:6] little endian
> > + */
> > +#define DRM_FORMAT_Q410		fourcc_code('Q', '4', '1', '0')
> > +
> > +/* 3 plane non-subsampled (444) YCrCb
> > + * 16 bits per component, but only 10 bits are used and 6 bits are padded
> > + * index 0: Y plane, [15:0] Y:x [10:6] little endian
> > + * index 1: Cr plane, [15:0] Cr:x [10:6] little endian
> > + * index 2: Cb plane, [15:0] Cb:x [10:6] little endian
> > + */
> > +#define DRM_FORMAT_Q401		fourcc_code('Q', '4', '0', '1')
> > +
> > +
> >  /*
> >   * 3 plane YCbCr
> >   * index 0: Y plane, [7:0] Y
> > -- 
> > 2.24.0