Re: [PATCH v2 16/23] staging: media: tegra-video: tegra20: simplify format align calculations

[Svyatoslav Ryhel <clamor95@gmail.com>]

пн, 22 вер. 2025 р. о 07:44 Mikko Perttunen <mperttunen@nvidia.com> пише:
>
> On Saturday, September 6, 2025 10:53 PM Svyatoslav Ryhel wrote:
> > Simplify format align calculations by slightly modifying supported formats
> > structure.
> >
> > Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
> > ---
> >  drivers/staging/media/tegra-video/tegra20.c | 41 ++++++++-------------
> >  1 file changed, 16 insertions(+), 25 deletions(-)
> >
> > diff --git a/drivers/staging/media/tegra-video/tegra20.c b/drivers/staging/media/tegra-video/tegra20.c
> > index 6e0b3b728623..781c4e8ec856 100644
> > --- a/drivers/staging/media/tegra-video/tegra20.c
> > +++ b/drivers/staging/media/tegra-video/tegra20.c
> > @@ -280,20 +280,8 @@ static void tegra20_fmt_align(struct v4l2_pix_format *pix, unsigned int bpp)
> >       pix->width  = clamp(pix->width,  TEGRA20_MIN_WIDTH,  TEGRA20_MAX_WIDTH);
> >       pix->height = clamp(pix->height, TEGRA20_MIN_HEIGHT, TEGRA20_MAX_HEIGHT);
> >
> > -     switch (pix->pixelformat) {
> > -     case V4L2_PIX_FMT_UYVY:
> > -     case V4L2_PIX_FMT_VYUY:
> > -     case V4L2_PIX_FMT_YUYV:
> > -     case V4L2_PIX_FMT_YVYU:
> > -             pix->bytesperline = roundup(pix->width, 2) * 2;
> > -             pix->sizeimage = roundup(pix->width, 2) * 2 * pix->height;
> > -             break;
> > -     case V4L2_PIX_FMT_YUV420:
> > -     case V4L2_PIX_FMT_YVU420:
> > -             pix->bytesperline = roundup(pix->width, 8);
> > -             pix->sizeimage = roundup(pix->width, 8) * pix->height * 3 / 2;
> > -             break;
> > -     }
> > +     pix->bytesperline = DIV_ROUND_UP(pix->width * bpp, 8);
>
> Assuming the bpp is coming from the format table below, this changes the value of bytesperline for planar formats. With this it'll be (width * 12) / 8 i.e. width * 3/2, which doesn't sound right.
>

Downstream uses soc_mbus_bytes_per_line for this calculation which was
deprecated some time ago, here is a fragment

s32 soc_mbus_bytes_per_line(u32 width, const struct soc_mbus_pixelfmt *mf)
{
 if (mf->fourcc == V4L2_PIX_FMT_JPEG)
 return 0;

 if (mf->layout != SOC_MBUS_LAYOUT_PACKED)
 return width * mf->bits_per_sample / 8;

 switch (mf->packing) {
 case SOC_MBUS_PACKING_NONE:
  return width * mf->bits_per_sample / 8;
 case SOC_MBUS_PACKING_2X8_PADHI:
 case SOC_MBUS_PACKING_2X8_PADLO:
 case SOC_MBUS_PACKING_EXTEND16:
  return width * 2;
 case SOC_MBUS_PACKING_1_5X8:
  return width * 3 / 2;
 case SOC_MBUS_PACKING_VARIABLE:
  return 0;
 }
   return -EINVAL;
}

V4L2_PIX_FMT_YUV420 and V4L2_PIX_FMT_YVU420 are classified as
SOC_MBUS_PACKING_1_5X8 hence we get width * 3/2

> > +     pix->sizeimage = pix->bytesperline * pix->height;
> >  }
> >
> >  /*
> > @@ -576,20 +564,23 @@ static const struct tegra_vi_ops tegra20_vi_ops = {
> >       .vi_stop_streaming = tegra20_vi_stop_streaming,
> >  };
> >
> > -#define TEGRA20_VIDEO_FMT(MBUS_CODE, BPP, FOURCC)    \
> > -{                                                    \
> > -     .code    = MEDIA_BUS_FMT_##MBUS_CODE,           \
> > -     .bpp     = BPP,                                 \
> > -     .fourcc  = V4L2_PIX_FMT_##FOURCC,               \
> > +#define TEGRA20_VIDEO_FMT(DATA_TYPE, BIT_WIDTH, MBUS_CODE, BPP, FOURCC)      \
> > +{                                                                    \
> > +     .img_dt         = TEGRA_IMAGE_DT_##DATA_TYPE,                   \
> > +     .bit_width      = BIT_WIDTH,                                    \
> > +     .code           = MEDIA_BUS_FMT_##MBUS_CODE,                    \
> > +     .bpp            = BPP,                                          \
> > +     .fourcc         = V4L2_PIX_FMT_##FOURCC,                        \
> >  }
> >
> >  static const struct tegra_video_format tegra20_video_formats[] = {
> > -     TEGRA20_VIDEO_FMT(UYVY8_2X8, 2, UYVY),
> > -     TEGRA20_VIDEO_FMT(VYUY8_2X8, 2, VYUY),
> > -     TEGRA20_VIDEO_FMT(YUYV8_2X8, 2, YUYV),
> > -     TEGRA20_VIDEO_FMT(YVYU8_2X8, 2, YVYU),
> > -     TEGRA20_VIDEO_FMT(UYVY8_2X8, 1, YUV420),
> > -     TEGRA20_VIDEO_FMT(UYVY8_2X8, 1, YVU420),
> > +     /* YUV422 */
> > +     TEGRA20_VIDEO_FMT(YUV422_8, 16, UYVY8_2X8, 16, UYVY),
> > +     TEGRA20_VIDEO_FMT(YUV422_8, 16, VYUY8_2X8, 16, VYUY),
> > +     TEGRA20_VIDEO_FMT(YUV422_8, 16, YUYV8_2X8, 16, YUYV),
> > +     TEGRA20_VIDEO_FMT(YUV422_8, 16, YVYU8_2X8, 16, YVYU),
> > +     TEGRA20_VIDEO_FMT(YUV422_8, 16, UYVY8_2X8, 12, YUV420),
> > +     TEGRA20_VIDEO_FMT(YUV422_8, 16, UYVY8_2X8, 12, YVU420),
> >  };
> >
> >  const struct tegra_vi_soc tegra20_vi_soc = {
> >
>
>
>
>