Re: [PATCH v11 1/5] media: v4l: Add definition for the Aspeed JPEG format

[Jammy Huang]

Hi Sakari,


After discussing with Hans, I will send patches on top to update this.

Thanks for your review.


On 2022/12/2 下午 10:23, Sakari Ailus wrote:
> Hi Jammy,
>
> Apologies for a late reply.
>
> On Fri, Oct 28, 2022 at 10:35:50AM +0800, 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@xxxxxxxxxxxxxx>
> > ---
> > v11:
> >    - no update
> > v10:
> >    - no update
> > v9:
> >    - Rebase on new kernel
> > 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
> > ---
> >   .../userspace-api/media/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/userspace-api/media/v4l/pixfmt-reserved.rst b/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst
> > index 0ff68cd8cf62..73cd99828010 100644
> > --- a/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst
> > +++ b/Documentation/userspace-api/media/v4l/pixfmt-reserved.rst
> > @@ -258,6 +258,23 @@ please make a proposal on the linux-media mailing list.
> >           and it is used by various multimedia hardware blocks like GPU, display
> >           controllers, ISP and video accelerators.
> >           It contains four planes for progressive video.
> > +    * .. _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.
> What does this refer to? If it's a URL, please add a reference as below.
>
> Also please run this on the patches:
>
> 	$ scripts/checkpatch.pl --strict --max-line-length=80
>
> > +
> > +        Decoder's implementation can be found here,
> > +        `aspeed_codec <https://github.com/AspeedTech-BMC/aspeed_codec/>`__
> >   .. raw:: latex
> >   
> >       \normalsize
> > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> > index fddba75d9074..8cb4b976064e 100644
> > --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> > @@ -1497,6 +1497,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
> >   		case V4L2_PIX_FMT_MT21C:	descr = "Mediatek Compressed Format"; break;
> >   		case V4L2_PIX_FMT_QC08C:	descr = "QCOM Compressed 8-bit Format"; break;
> >   		case V4L2_PIX_FMT_QC10C:	descr = "QCOM Compressed 10-bit 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 86cae23cc446..870a7e5ef8ca 100644
> > --- a/include/uapi/linux/videodev2.h
> > +++ b/include/uapi/linux/videodev2.h
> > @@ -775,6 +775,7 @@ struct v4l2_pix_format {
> >   #define V4L2_PIX_FMT_HI240    v4l2_fourcc('H', 'I', '2', '4') /* BTTV 8-bit dithered RGB */
> >   #define V4L2_PIX_FMT_QC08C    v4l2_fourcc('Q', '0', '8', 'C') /* Qualcomm 8-bit compressed */
> >   #define V4L2_PIX_FMT_QC10C    v4l2_fourcc('Q', '1', '0', 'C') /* Qualcomm 10-bit compressed */
> > +#define V4L2_PIX_FMT_AJPG     v4l2_fourcc('A', 'J', 'P', 'G') /* Aspeed JPEG */
> >   
> >   /* 10bit raw 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