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

[Jammy Huang <jammy_huang@xxxxxxxxxxxxxx>]

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@xxxxxxxxxxxxxx>
> > ---
> > 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??

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