Re: [PATCH 2/2] [WIP]: media: Add Synaptics compressed tiled format

[Nicolas Dufresne]

Le vendredi 19 août 2022 à 02:13 +0300, Laurent Pinchart a écrit :
> On Thu, Aug 18, 2022 at 02:33:42PM +0800, Hsia-Jun Li wrote:
> > On 8/18/22 14:06, Tomasz Figa wrote:
> > > On Tue, Aug 9, 2022 at 1:28 AM Hsia-Jun Li <randy.li@xxxxxxxxxxxxx> wrote:
> > > > 
> > > > From: "Hsia-Jun(Randy) Li" <randy.li@xxxxxxxxxxxxx>
> > > > 
> > > > The most of detail has been written in the drm.
> 
> This patch still needs a description of the format, which should go to
> Documentation/userspace-api/media/v4l/.
> 
> > > > Please notice that the tiled formats here request
> > > > one more plane for storing the motion vector metadata.
> > > > This buffer won't be compressed, so you can't append
> > > > it to luma or chroma plane.
> > > 
> > > Does the motion vector buffer need to be exposed to userspace? Is the
> > > decoder stateless (requires userspace to specify the reference frames)
> > > or stateful (manages the entire decoding process internally)?
> > 
> > No, users don't need to access them at all. Just they need a different 
> > dma-heap.
> > 
> > You would only get the stateful version of both encoder and decoder.
> 
> Shouldn't the motion vectors be stored in a separate V4L2 buffer,
> submitted through a different queue then ?

Imho, I believe these should be invisible to users and pooled separately to
reduce the overhead. The number of reference is usually lower then the number of
allocated display buffers.

> 
> > > > Signed-off-by: Hsia-Jun(Randy) Li <randy.li@xxxxxxxxxxxxx>
> > > > ---
> > > >   drivers/media/v4l2-core/v4l2-common.c | 1 +
> > > >   drivers/media/v4l2-core/v4l2-ioctl.c  | 2 ++
> > > >   include/uapi/linux/videodev2.h        | 2 ++
> > > >   3 files changed, 5 insertions(+)
> > > > 
> > > > diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c
> > > > index e0fbe6ba4b6c..f645278b3055 100644
> > > > --- a/drivers/media/v4l2-core/v4l2-common.c
> > > > +++ b/drivers/media/v4l2-core/v4l2-common.c
> > > > @@ -314,6 +314,7 @@ const struct v4l2_format_info *v4l2_format_info(u32 format)
> > > >                  { .format = V4L2_PIX_FMT_SGBRG12,       .pixel_enc = V4L2_PIXEL_ENC_BAYER, .mem_planes = 1, .comp_planes = 1, .bpp = { 2, 0, 0, 0 }, .hdiv = 1, .vdiv = 1 },
> > > >                  { .format = V4L2_PIX_FMT_SGRBG12,       .pixel_enc = V4L2_PIXEL_ENC_BAYER, .mem_planes = 1, .comp_planes = 1, .bpp = { 2, 0, 0, 0 }, .hdiv = 1, .vdiv = 1 },
> > > >                  { .format = V4L2_PIX_FMT_SRGGB12,       .pixel_enc = V4L2_PIXEL_ENC_BAYER, .mem_planes = 1, .comp_planes = 1, .bpp = { 2, 0, 0, 0 }, .hdiv = 1, .vdiv = 1 },
> > > > +               { .format = V4L2_PIX_FMT_NV12M_V4H1C, .pixel_enc = V4L2_PIXEL_ENC_YUV, .mem_planes = 5, .comp_planes = 2, .bpp = { 1, 2, 0, 0 }, .hdiv = 2, .vdiv = 2, .block_w = { 128, 128 }, .block_h = { 128, 128 } },
> > > >          };
> > > >          unsigned int i;
> > > > 
> > > > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> > > > index e6fd355a2e92..8f65964aff08 100644
> > > > --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> > > > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> > > > @@ -1497,6 +1497,8 @@ 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_NV12M_V4H1C:  descr = "Synaptics Compressed 8-bit tiled Format";break;
> > > > +               case V4L2_PIX_FMT_NV12M_10_V4H3P8C:     descr = "Synaptics Compressed 10-bit tiled Format";break;
> > > >                  default:
> > > >                          if (fmt->description[0])
> > > >                                  return;
> > > > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> > > > index 01e630f2ec78..7e928cb69e7c 100644
> > > > --- a/include/uapi/linux/videodev2.h
> > > > +++ b/include/uapi/linux/videodev2.h
> > > > @@ -661,6 +661,8 @@ struct v4l2_pix_format {
> > > >   #define V4L2_PIX_FMT_NV12MT_16X16 v4l2_fourcc('V', 'M', '1', '2') /* 12  Y/CbCr 4:2:0 16x16 tiles */
> > > >   #define V4L2_PIX_FMT_NV12M_8L128      v4l2_fourcc('N', 'A', '1', '2') /* Y/CbCr 4:2:0 8x128 tiles */
> > > >   #define V4L2_PIX_FMT_NV12M_10BE_8L128 v4l2_fourcc_be('N', 'T', '1', '2') /* Y/CbCr 4:2:0 10-bit 8x128 tiles */
> > > > +#define V4L2_PIX_FMT_NV12M_V4H1C v4l2_fourcc('S', 'Y', '1', '2')   /* 12  Y/CbCr 4:2:0 tiles */
> > > > +#define V4L2_PIX_FMT_NV12M_10_V4H3P8C v4l2_fourcc('S', 'Y', '1', '0')   /* 12  Y/CbCr 4:2:0 10-bits tiles */
> > > > 
> > > >   /* Bayer formats - see http://www.siliconimaging.com/RGB%20Bayer.htm */
> > > >   #define V4L2_PIX_FMT_SBGGR8  v4l2_fourcc('B', 'A', '8', '1') /*  8  BGBG.. GRGR.. */
>