linux-kernel - Re: [PATCH v8 1/4] media: v4l: Add definition for the Aspeed JPEG format

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Message-ID: <98096e97-68cc-18fd-d2b6-3477f57f05bd@aspeedtech.com>
Date:   Mon, 17 Jan 2022 15:18:22 +0800
From:   Jammy Huang <jammy_huang@...eedtech.com>
To:     Joel Stanley <joel@....id.au>
CC:     Hans Verkuil <hverkuil-cisco@...all.nl>,
        "sakari.ailus@...ux.intel.com" <sakari.ailus@...ux.intel.com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "eajames@...ux.ibm.com" <eajames@...ux.ibm.com>,
        "mchehab@...nel.org" <mchehab@...nel.org>,
        "andrew@...id.au" <andrew@...id.au>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "openbmc@...ts.ozlabs.org" <openbmc@...ts.ozlabs.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v8 1/4] media: v4l: Add definition for the Aspeed JPEG
 format

On 2022/1/17 上午 10:24, Joel Stanley wrote:
> On Mon, 17 Jan 2022 at 02:00, Jammy Huang <jammy_huang@...eedtech.com> wrote:
>> Hi Hans,
>>
>> On 2022/1/14 下午 04:11, Hans Verkuil wrote:
>>> On 24/12/2021 02:27, Jammy Huang wrote:
>>>> This introduces support for the Aspeed JPEG format, where the new frame
>>>> can refer to previous frame to reduce the amount of compressed data. The
>>>> concept is similar to I/P frame of video compression. It will compare the
>>>> new frame with previous one to decide which macroblock's data is
>>>> changed, and only the changed macroblocks will be compressed.
>>>>
>>>> This Aspeed JPEG format is used by the video engine on Aspeed platforms,
>>>> which is generally adapted for remote KVM.
>>>>
>>>> Signed-off-by: Jammy Huang <jammy_huang@...eedtech.com>
>>>> ---
>>>> v8:
>>>>     - Add decoder information for aspeed-jpeg
>>>> v7:
>>>>     - Add more information for aspeed-jpeg
>>>> v6:
>>>>     - Update description for new format, aspeed-jpeg, in Documentation.
>>>> v5:
>>>>     - no update
>>>> v4:
>>>>     - new
>>>> ---
>>>>    .../media/uapi/v4l/pixfmt-reserved.rst          | 17 +++++++++++++++++
>>>>    drivers/media/v4l2-core/v4l2-ioctl.c            |  1 +
>>>>    include/uapi/linux/videodev2.h                  |  1 +
>>>>    3 files changed, 19 insertions(+)
>>>>
>>>> diff --git a/Documentation/media/uapi/v4l/pixfmt-reserved.rst b/Documentation/media/uapi/v4l/pixfmt-reserved.rst
>>> This is the wrong file! It should be:
>>>
>>> Documentation/userspace-api/media/v4l/pixfmt-reserved.rst
>> Thanks, I just used git format-patch to generate the cover-letter and
>> didn't notice this.
>>
>> It looks like the file, pixfmt-reserved.rst, has different path in
>> different Linux kernel,
>>
>> * 5.4:           Documentation/media/uapi/v4l/pixfmt-reserved.rst
>>
>> * 5.10/5.15: Documentation/userspace-api/media/v4l/pixfmt-reserved.rst
>>
>> 5.4 is the one I based to submit the patches.
>>
>> Could you suggest the kernel that I should based to submit these patches??
> You should always submit based on the latest release.
>
> There are sometimes exceptions where you will base your patches on
> something even newer, but generally you should grab the latest.
>
> Be sure to re-test on the latest kernel before submitting.
OK, thank you.
>
> Cheers,
>
> Joel
>
>> I will need to change the number of V4L2_CID_USER_ASPEED_BASE per different
>>
>> linux kernel as well.
>>
>>> Regards,
>>>
>>>        Hans
>>>
>>>> index b2cd155e691b..1d0dc8d86ed7 100644
>>>> --- a/Documentation/media/uapi/v4l/pixfmt-reserved.rst
>>>> +++ b/Documentation/media/uapi/v4l/pixfmt-reserved.rst
>>>> @@ -264,6 +264,23 @@ please make a proposal on the linux-media mailing list.
>>>>       of tiles, resulting in 32-aligned resolutions for the luminance plane
>>>>       and 16-aligned resolutions for the chrominance plane (with 2x2
>>>>       subsampling).
>>>> +    * .. _V4L2-PIX-FMT-AJPG:
>>>> +
>>>> +      - ``V4L2_PIX_FMT_AJPG``
>>>> +      - 'AJPG'
>>>> +      - ASPEED JPEG format used by the aspeed-video driver on Aspeed platforms,
>>>> +        which is generally adapted for remote KVM.
>>>> +        On each frame compression, I will compare the new frame with previous
>>>> +        one to decide which macroblock's data is changed, and only the changed
>>>> +        macroblocks will be compressed.
>>>> +
>>>> +        The implementation is based on AST2600 A3 datasheet, revision 0.9, which
>>>> +        is not publicly available. Or you can reference Video stream data format
>>>> +        – ASPEED mode compression of SDK_User_Guide which available on
>>>> +        AspeedTech-BMC/openbmc/releases.
>>>> +
>>>> +        Decoder's implementation can be found here,
>>>> +        `https://github.com/AspeedTech-BMC/aspeed_codec/ <https://github.com/AspeedTech-BMC/aspeed_codec/>`__
>>>>
>>>>    .. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.7cm}|
>>>>
>>>> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
>>>> index 24db33f803c0..00dde01d2f97 100644
>>>> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
>>>> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
>>>> @@ -1378,6 +1378,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
>>>>               case V4L2_PIX_FMT_S5C_UYVY_JPG: descr = "S5C73MX interleaved UYVY/JPEG"; break;
>>>>               case V4L2_PIX_FMT_MT21C:        descr = "Mediatek Compressed Format"; break;
>>>>               case V4L2_PIX_FMT_SUNXI_TILED_NV12: descr = "Sunxi Tiled NV12 Format"; break;
>>>> +            case V4L2_PIX_FMT_AJPG:         descr = "Aspeed JPEG"; break;
>>>>               default:
>>>>                       if (fmt->description[0])
>>>>                               return;
>>>> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
>>>> index 3210b3c82a4a..994eb6155ea9 100644
>>>> --- a/include/uapi/linux/videodev2.h
>>>> +++ b/include/uapi/linux/videodev2.h
>>>> @@ -726,6 +726,7 @@ struct v4l2_pix_format {
>>>>    #define V4L2_PIX_FMT_INZI     v4l2_fourcc('I', 'N', 'Z', 'I') /* Intel Planar Greyscale 10-bit and Depth 16-bit */
>>>>    #define V4L2_PIX_FMT_SUNXI_TILED_NV12 v4l2_fourcc('S', 'T', '1', '2') /* Sunxi Tiled NV12 Format */
>>>>    #define V4L2_PIX_FMT_CNF4     v4l2_fourcc('C', 'N', 'F', '4') /* Intel 4-bit packed depth confidence information */
>>>> +#define V4L2_PIX_FMT_AJPG     v4l2_fourcc('A', 'J', 'P', 'G') /* Aspeed JPEG */
>>>>
>>>>    /* 10bit raw bayer packed, 32 bytes for every 25 pixels, last LSB 6 bits unused */
>>>>    #define V4L2_PIX_FMT_IPU3_SBGGR10  v4l2_fourcc('i', 'p', '3', 'b') /* IPU3 packed 10-bit BGGR bayer */
>> --
>> Best Regards
>> Jammy
>>
-- 
Best Regards
Jammy