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

Mon May 25 11:08:11 UTC 2020

Hi,

On 2020-05-15 15:37, Brian Starkey wrote:
> 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.

This pixel format seem to match the memory layout used for 10-bit 4:2:0 by the
Rockchip Video Decoder, for the rkvdec a 4:2:2 format is also needed (maybe NV20?).

>From what I can tell the rockchip specific pixel format has previously been submitted in [1]
and GStreamer use NV12_10LE40 (fourcc RK20) for this pixel format.

[1] https://patchwork.freedesktop.org/patch/276029/

> 
> 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 },

For a 4:2:0 format I wonder if the char_per_block value is correct for the second plane,
using the following formula to calculate the pitch seem to result in only half expected width.
Maybe .char_per_block { 5, 10, 0 } could be correct?

pitch = (width * char_per_block[1]) / block_w[1] / hsub

for 16x16 this would be

pitch[1] = (16 * 5) / 4 / 2 = 10 bytes
vs
pitch[1] = (16 * 10) / 4 / 2 = 20 bytes

height[1] = 16 / 2 = 8

Regards,
Jonas

>>> +		{ .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
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 