linux-kernel - Re: [PATCH 2/2] media: v4l: Add new 10-bit packed grayscale format

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Message-ID: <20180507105956.o5fhjq7udmo7qt2z@valkosipuli.retiisi.org.uk>
Date:   Mon, 7 May 2018 13:59:56 +0300
From:   Sakari Ailus <sakari.ailus@....fi>
To:     Todor Tomov <todor.tomov@...aro.org>
Cc:     mchehab@...nel.org, hverkuil@...all.nl,
        laurent.pinchart@...asonboard.com, linux-media@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] media: v4l: Add new 10-bit packed grayscale format

Hi Todor,

On Fri, Apr 27, 2018 at 02:40:39PM +0300, Todor Tomov wrote:
> The new format will be called V4L2_PIX_FMT_Y10P.
> It is similar to the V4L2_PIX_FMT_SBGGR10P family formats
> but V4L2_PIX_FMT_Y10P is a grayscale format.
> 
> Signed-off-by: Todor Tomov <todor.tomov@...aro.org>
> ---
>  Documentation/media/uapi/v4l/pixfmt-y10p.rst | 31 ++++++++++++++++++++++++++++
>  Documentation/media/uapi/v4l/yuv-formats.rst |  1 +
>  drivers/media/v4l2-core/v4l2-ioctl.c         |  1 +
>  include/uapi/linux/videodev2.h               |  1 +
>  4 files changed, 34 insertions(+)
>  create mode 100644 Documentation/media/uapi/v4l/pixfmt-y10p.rst
> 
> diff --git a/Documentation/media/uapi/v4l/pixfmt-y10p.rst b/Documentation/media/uapi/v4l/pixfmt-y10p.rst
> new file mode 100644
> index 0000000..0018fe7
> --- /dev/null
> +++ b/Documentation/media/uapi/v4l/pixfmt-y10p.rst
> @@ -0,0 +1,31 @@
> +.. -*- coding: utf-8; mode: rst -*-
> +
> +.. _V4L2-PIX-FMT-Y10P:
> +
> +******************************
> +V4L2_PIX_FMT_Y10P ('Y10P')
> +******************************
> +
> +Grey-scale image as a MIPI RAW10 packed array
> +
> +
> +Description
> +===========
> +
> +This is a packed grey-scale image format with a depth of 10 bits per
> +pixel. Every four consecutive pixels are packed into 5 bytes. Each of
> +the first 4 bytes contain the 8 high order bits of the pixels, and
> +the 5th byte contains the 2 least significants bits of each pixel,
> +in the same order.
> +
> +**Bit-packed representation.**
> +
> +.. flat-table::
> +    :header-rows:  0
> +    :stub-columns: 0
> +
> +    * - Y'\ :sub:`00[9:2]`
> +      - Y'\ :sub:`01[9:2]`
> +      - Y'\ :sub:`02[9:2]`
> +      - Y'\ :sub:`03[9:2]`
> +      - Y'\ :sub:`03[1:0]`\ Y'\ :sub:`02[1:0]`\ Y'\ :sub:`01[1:0]`\ Y'\ :sub:`00[1:0]`

Could you add which exact bits the two LSBs of each pixel go to in the last
byte, as in the 10-bit packed Bayer format documentation?

> diff --git a/Documentation/media/uapi/v4l/yuv-formats.rst b/Documentation/media/uapi/v4l/yuv-formats.rst
> index 3334ea4..9ab0592 100644
> --- a/Documentation/media/uapi/v4l/yuv-formats.rst
> +++ b/Documentation/media/uapi/v4l/yuv-formats.rst
> @@ -29,6 +29,7 @@ to brightness information.
>      pixfmt-y10
>      pixfmt-y12
>      pixfmt-y10b
> +    pixfmt-y10p
>      pixfmt-y16
>      pixfmt-y16-be
>      pixfmt-y8i
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index f48c505..bdf2399 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -1147,6 +1147,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
>  	case V4L2_PIX_FMT_Y16:		descr = "16-bit Greyscale"; break;
>  	case V4L2_PIX_FMT_Y16_BE:	descr = "16-bit Greyscale BE"; break;
>  	case V4L2_PIX_FMT_Y10BPACK:	descr = "10-bit Greyscale (Packed)"; break;
> +	case V4L2_PIX_FMT_Y10P:		descr = "10-bit Greyscale (MIPI Packed)"; break;
>  	case V4L2_PIX_FMT_Y8I:		descr = "Interleaved 8-bit Greyscale"; break;
>  	case V4L2_PIX_FMT_Y12I:		descr = "Interleaved 12-bit Greyscale"; break;
>  	case V4L2_PIX_FMT_Z16:		descr = "16-bit Depth"; break;
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 600877b..b24ab720 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -522,6 +522,7 @@ struct v4l2_pix_format {
>  
>  /* Grey bit-packed formats */
>  #define V4L2_PIX_FMT_Y10BPACK    v4l2_fourcc('Y', '1', '0', 'B') /* 10  Greyscale bit-packed */
> +#define V4L2_PIX_FMT_Y10P    v4l2_fourcc('Y', '1', '0', 'P') /* 10  Greyscale, MIPI RAW10 packed */
>  
>  /* Palette formats */
>  #define V4L2_PIX_FMT_PAL8    v4l2_fourcc('P', 'A', 'L', '8') /*  8  8-bit palette */
> -- 
> 2.7.4
> 

-- 
Sakari Ailus
e-mail: sakari.ailus@....fi