linux-kernel - Re: [PATCH 04/10] media: Add Y312 video format

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Message-ID: <a46040a4-f274-1e07-0829-86facf550496@xs4all.nl>
Date:   Fri, 27 Jan 2023 15:42:04 +0100
From:   Hans Verkuil <hverkuil-cisco@...all.nl>
To:     Ming Qian <ming.qian@....com>, mchehab@...nel.org,
        mirela.rabulea@....nxp.com
Cc:     shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
        festevam@...il.com, xiahong.bao@....com, linux-imx@....com,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 04/10] media: Add Y312 video format

On 20/12/2022 04:11, Ming Qian wrote:
> Y312 is a YUV format with 12-bits per component like YUV24,
> expanded to 16bits.
> Data in the 12 high bits, zeros in the 4 low bits,
> arranged in little endian order.
> 
> Signed-off-by: Ming Qian <ming.qian@....com>
> ---
>  .../media/v4l/pixfmt-packed-yuv.rst           | 28 +++++++++++++++++++
>  drivers/media/v4l2-core/v4l2-common.c         |  1 +
>  drivers/media/v4l2-core/v4l2-ioctl.c          |  1 +
>  include/uapi/linux/videodev2.h                |  1 +
>  4 files changed, 31 insertions(+)
> 
> diff --git a/Documentation/userspace-api/media/v4l/pixfmt-packed-yuv.rst b/Documentation/userspace-api/media/v4l/pixfmt-packed-yuv.rst
> index 39ded0b1e65c..a91c30ba6b73 100644
> --- a/Documentation/userspace-api/media/v4l/pixfmt-packed-yuv.rst
> +++ b/Documentation/userspace-api/media/v4l/pixfmt-packed-yuv.rst
> @@ -257,6 +257,34 @@ the second byte and Y'\ :sub:`7-0` in the third byte.
>      - The padding bits contain undefined values that must be ignored by all
>        applications and drivers.
>  
> +The next lists the packed YUV 4:4:4 formats with more than 8 bits per component.
> +expand the bits per component to 16 bits, data in the high bits, zeros in the low bits,
> +arranged in little endian order. storing 1 pixels in 6 bytes.
> +
> +.. flat-table:: Packed YUV 4:4:4 Image Formats (more than 8bpc)
> +    :header-rows: 1
> +    :stub-columns: 0
> +
> +    * - Identifier
> +      - Code
> +      - Byte 1-0
> +      - Byte 3-2
> +      - Byte 5-4
> +      - Byte 7-6
> +      - Byte 9-8
> +      - Byte 11-10
> +
> +    * .. _V4L2-PIX-FMT-Y312:
> +
> +      - ``V4L2_PIX_FMT_Y312``
> +      - 'Y312'
> +
> +      - Y'\ :sub:`0`
> +      - Cb\ :sub:`0`
> +      - Cr\ :sub:`0`
> +      - Y'\ :sub:`1`
> +      - Cb\ :sub:`1`
> +      - Cr\ :sub:`1`
>  
>  4:2:2 Subsampling
>  =================
> diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
> index 21ace56fac04..332d4b11bc1b 100644
> --- a/drivers/media/v4l2-core/v4l2-common.c
> +++ b/drivers/media/v4l2-core/v4l2-common.c
> @@ -259,6 +259,7 @@ const struct v4l2_format_info *v4l2_format_info(u32 format)
>  		{ .format = V4L2_PIX_FMT_UYVY,    .pixel_enc = V4L2_PIXEL_ENC_YUV, .mem_planes = 1, .comp_planes = 1, .bpp = { 2, 0, 0, 0 }, .hdiv = 2, .vdiv = 1 },
>  		{ .format = V4L2_PIX_FMT_VYUY,    .pixel_enc = V4L2_PIXEL_ENC_YUV, .mem_planes = 1, .comp_planes = 1, .bpp = { 2, 0, 0, 0 }, .hdiv = 2, .vdiv = 1 },
>  		{ .format = V4L2_PIX_FMT_Y212,    .pixel_enc = V4L2_PIXEL_ENC_YUV, .mem_planes = 1, .comp_planes = 1, .bpp = { 4, 0, 0, 0 }, .hdiv = 2, .vdiv = 1 },
> +		{ .format = V4L2_PIX_FMT_Y312,    .pixel_enc = V4L2_PIXEL_ENC_YUV, .mem_planes = 1, .comp_planes = 1, .bpp = { 6, 0, 0, 0 }, .hdiv = 1, .vdiv = 1 },
>  
>  		/* YUV planar formats */
>  		{ .format = V4L2_PIX_FMT_NV12,    .pixel_enc = V4L2_PIXEL_ENC_YUV, .mem_planes = 1, .comp_planes = 2, .bpp = { 1, 2, 0, 0 }, .hdiv = 2, .vdiv = 2 },
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index 4d5f722b674a..5b97d7e5dbbf 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -1343,6 +1343,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
>  	case V4L2_PIX_FMT_HI240:	descr = "8-bit Dithered RGB (BTTV)"; break;
>  	case V4L2_PIX_FMT_M420:		descr = "YUV 4:2:0 (M420)"; break;
>  	case V4L2_PIX_FMT_Y212:		descr = "12-bit Depth YUYV 4:2:2"; break;
> +	case V4L2_PIX_FMT_Y312:		descr = "12-bit Depth YUV 4:4:4"; break;
>  	case V4L2_PIX_FMT_NV12:		descr = "Y/UV 4:2:0"; break;
>  	case V4L2_PIX_FMT_NV21:		descr = "Y/VU 4:2:0"; break;
>  	case V4L2_PIX_FMT_NV16:		descr = "Y/UV 4:2:2"; break;
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index b8a501dccfa4..3475331737af 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -619,6 +619,7 @@ struct v4l2_pix_format {
>  #define V4L2_PIX_FMT_YUVX32  v4l2_fourcc('Y', 'U', 'V', 'X') /* 32  YUVX-8-8-8-8  */
>  #define V4L2_PIX_FMT_M420    v4l2_fourcc('M', '4', '2', '0') /* 12  YUV 4:2:0 2 lines y, 1 line uv interleaved */
>  #define V4L2_PIX_FMT_Y212    v4l2_fourcc('Y', '2', '1', '2') /* 32  YUYV 12-bit per component */
> +#define V4L2_PIX_FMT_Y312    v4l2_fourcc('Y', '3', '1', '2') /* 48  YUV 4:4:4 12-bit per component */

YUV24_12 would work, I think. Y312 suggests a greyscale format, so that's definitely wrong.

Regards,

	Hans

>  
>  /* two planes -- one Y, one Cr + Cb interleaved  */
>  #define V4L2_PIX_FMT_NV12    v4l2_fourcc('N', 'V', '1', '2') /* 12  Y/CbCr 4:2:0  */