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Message-ID: <4198615.hdfAi7Kttb@senjougahara>
Date: Mon, 22 Sep 2025 15:23:04 +0900
From: Mikko Perttunen <mperttunen@...dia.com>
To: Svyatoslav Ryhel <clamor95@...il.com>
Cc: Thierry Reding <thierry.reding@...il.com>,
 Thierry Reding <treding@...dia.com>, Jonathan Hunter <jonathanh@...dia.com>,
 Sowjanya Komatineni <skomatineni@...dia.com>,
 Luca Ceresoli <luca.ceresoli@...tlin.com>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Prashant Gaikwad <pgaikwad@...dia.com>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>,
 Mauro Carvalho Chehab <mchehab@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Dmitry Osipenko <digetx@...il.com>,
 Jonas Schwöbel <jonasschwoebel@...oo.de>,
 Charan Pedumuru <charan.pedumuru@...il.com>, dri-devel@...ts.freedesktop.org,
 devicetree@...r.kernel.org, linux-tegra@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
 linux-clk@...r.kernel.org, linux-staging@...ts.linux.dev
Subject:
 Re: [PATCH v2 16/23] staging: media: tegra-video: tegra20: simplify format
 align calculations

On Monday, September 22, 2025 2:13 PM Svyatoslav Ryhel wrote:
> пн, 22 вер. 2025 р. о 07:44 Mikko Perttunen <mperttunen@...dia.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@...il.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

Googling this brings up the entry

{
	.code = V4L2_MBUS_FMT_YUYV8_1_5X8,
	.fmt = {
		.fourcc			= V4L2_PIX_FMT_YUV420,
		.name			= "YUYV 4:2:0",
		.bits_per_sample		= 8,
		.packing			= SOC_MBUS_PACKING_1_5X8,
		.order			= SOC_MBUS_ORDER_LE,
		.layout			= SOC_MBUS_LAYOUT_PACKED,
	},
}

which matches that you're describing. It doesn't make sense to me, since it at the same time specifies PIX_FMT_YUV420 (which is planar with 3 planes, as documented by include/uapi/linux/videodev2.h), and LAYOUT_PACKED

/**
 * enum soc_mbus_layout - planes layout in memory
 * @SOC_MBUS_LAYOUT_PACKED:		color components packed
 * @SOC_MBUS_LAYOUT_PLANAR_2Y_U_V:	YUV components stored in 3 planes (4:2:2)
 * @SOC_MBUS_LAYOUT_PLANAR_2Y_C:	YUV components stored in a luma and a
 *					chroma plane (C plane is half the size
 *					of Y plane)
 * @SOC_MBUS_LAYOUT_PLANAR_Y_C:		YUV components stored in a luma and a
 *					chroma plane (C plane is the same size
 *					as Y plane)
 */
enum soc_mbus_layout {
	SOC_MBUS_LAYOUT_PACKED = 0,
	SOC_MBUS_LAYOUT_PLANAR_2Y_U_V,
	SOC_MBUS_LAYOUT_PLANAR_2Y_C,
	SOC_MBUS_LAYOUT_PLANAR_Y_C,
};

i.e. non-planar. The code in the driver is handling it as three planes as well, with addresses VB0_BASE_ADDRESS/VB0_BASE_ADDRESS_U/VB0_BASE_ADDRESS_V. Since the planes are separate, there should be no need to have more than 'width' samples per line.

> 
> > > +     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 = {
> > >
> >
> >
> >
> >





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