Le lundi 13 février 2023 à 09:22 +0000, Ming Qian a écrit :
> > From: Nicolas Dufresne <nicolas@xxxxxxxxxxxx>
> > Sent: 2023年2月10日 23:18
> > To: Ming Qian <ming.qian@xxxxxxx>; mchehab@xxxxxxxxxx; Mirela Rabulea
> > (OSS) <mirela.rabulea@xxxxxxxxxxx>; hverkuil-cisco@xxxxxxxxx
> > Cc: shawnguo@xxxxxxxxxx; s.hauer@xxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx;
> > festevam@xxxxxxxxx; X.H. Bao <xiahong.bao@xxxxxxx>; dl-linux-imx <linux-
> > imx@xxxxxxx>; linux-media@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > devicetree@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > Subject: [EXT] Re: [PATCH v2 02/10] media: Add Y012 video format
> >
> > Caution: EXT Email
> >
> > Le mercredi 01 février 2023 à 14:02 +0800, Ming Qian a écrit :
> > > Y012 is a luma-only formats with 12-bits per pixel, expanded to
> > > 16bits.
> > > Data in the 12 high bits, zeros in the 4 low bits, arranged in little
> > > endian order.
> > >
> > > Signed-off-by: Ming Qian <ming.qian@xxxxxxx>
> > > ---
> > > .../userspace-api/media/v4l/pixfmt-yuv-luma.rst | 11 +++++++++++
> > > drivers/media/v4l2-core/v4l2-ioctl.c | 1 +
> > > include/uapi/linux/videodev2.h | 1 +
> > > 3 files changed, 13 insertions(+)
> > >
> > > diff --git a/Documentation/userspace-api/media/v4l/pixfmt-yuv-luma.rst
> > > b/Documentation/userspace-api/media/v4l/pixfmt-yuv-luma.rst
> > > index 6a387f9df3ba..3ffa29000238 100644
> > > --- a/Documentation/userspace-api/media/v4l/pixfmt-yuv-luma.rst
> > > +++ b/Documentation/userspace-api/media/v4l/pixfmt-yuv-luma.rst
> > > @@ -103,6 +103,17 @@ are often referred to as greyscale formats.
> > > - ...
> > > - ...
> > >
> > > + * .. _V4L2-PIX-FMT-Y012:
> >
> > Why the 0, can't this be name Y12 (just like Y14) ?
> >
>
> Hi Nicolas,
> As the V4L2_PIX_FMT_Y12 is defined, but it's data is in the 12 low bits,
> zeros in the high bits.
> Here I want to place the 12 bits data in the high bits, with zeros in the
> 4 low bits.
> So I add 0 before 12, I want to say that the low bits are padding data 0.
>
> Or do you have a better suggestion?
I see, I had missed this aspect. I think in this context, it would be fair
naming. Maybe drop a note in the doc saying just that:
"In contrast to V4L2_PIX_FMT_Y12 format, which have its padding located in the
most significant bits of the 16 bit word".
Or something similar.,
Nicolas
>
> Ming
>
> > > +
> > > + - ``V4L2_PIX_FMT_Y012``
> > > + - 'Y012'
> > > +
> > > + - Y'\ :sub:`0`\ [3:0] `0000`
> > > + - Y'\ :sub:`0`\ [11:4]
> > > + - ...
> > > + - ...
> > > + - ...
> > > +
> > > * .. _V4L2-PIX-FMT-Y14:
> > >
> > > - ``V4L2_PIX_FMT_Y14``
> > > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c
> > > b/drivers/media/v4l2-core/v4l2-ioctl.c
> > > index 067dbdd0a9ef..0ee730aa6cc7 100644
> > > --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> > > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> > > @@ -1303,6 +1303,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc
> > *fmt)
> > > case V4L2_PIX_FMT_Y6: descr = "6-bit Greyscale"; break;
> > > case V4L2_PIX_FMT_Y10: descr = "10-bit Greyscale"; break;
> > > case V4L2_PIX_FMT_Y12: descr = "12-bit Greyscale"; break;
> > > + case V4L2_PIX_FMT_Y012: descr = "12-bit Greyscale"; break;
> > > case V4L2_PIX_FMT_Y14: descr = "14-bit Greyscale"; break;
> > > case V4L2_PIX_FMT_Y16: descr = "16-bit Greyscale"; break;
> > > case V4L2_PIX_FMT_Y16_BE: descr = "16-bit Greyscale BE";
> > > break;
> > > diff --git a/include/uapi/linux/videodev2.h
> > > b/include/uapi/linux/videodev2.h index 5448aa3b7858..3d8f89bff33c
> > > 100644
> > > --- a/include/uapi/linux/videodev2.h
> > > +++ b/include/uapi/linux/videodev2.h
> > > @@ -583,6 +583,7 @@ struct v4l2_pix_format {
> > > #define V4L2_PIX_FMT_Y6 v4l2_fourcc('Y', '0', '6', ' ') /* 6
> > > Greyscale */
> > > #define V4L2_PIX_FMT_Y10 v4l2_fourcc('Y', '1', '0', ' ') /* 10
> > > Greyscale
> > */
> > > #define V4L2_PIX_FMT_Y12 v4l2_fourcc('Y', '1', '2', ' ') /* 12
> > > Greyscale
> > */
> > > +#define V4L2_PIX_FMT_Y012 v4l2_fourcc('Y', '0', '1', '2') /* 12
> > > Greyscale
> > */
> > > #define V4L2_PIX_FMT_Y14 v4l2_fourcc('Y', '1', '4', ' ') /* 14
> > > Greyscale
> > */
> > > #define V4L2_PIX_FMT_Y16 v4l2_fourcc('Y', '1', '6', ' ') /* 16
> > > Greyscale
> > */
> > > #define V4L2_PIX_FMT_Y16_BE v4l2_fourcc_be('Y', '1', '6', ' ') /* 16
> > > Greyscale BE */
>
