Re: [PATCH] [media] v4l: Add luma 16-bit interlaced pixel format

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Hi Dmitry,

On Sun, Aug 18, 2024 at 04:20:50PM +0300, Dmitry Perchanov wrote:
> Hi Laurent,
> 
> Thanks for your review, I will update patch to match latest,
> as now it conflicts with merged updates.
> 
> Please see inline.
> 
> On Fri, 2024-08-02 at 18:26 +0300, Laurent Pinchart wrote:
> > On Sun, Jul 28, 2024 at 06:35:57AM -0400, Dmitry Perchanov wrote:
> > > The formats added by this patch are:
> > > 
> > >         V4L2_PIX_FMT_Y16I
> > >         UVC_GUID_FORMAT_Y16I
> > > 
> > > Interlaced lumina format primary use in RealSense
> > > Depth cameras with stereo stream for left and right
> > > image sensors.
> > > 
> > > Signed-off-by: Dmitry Perchanov <dmitry.perchanov@xxxxxxxxx>
> > 
> > The format itself looks fine. Could you split this patch in two, with
> > one patch that defines the new format (documentation, v4l2-ioctl.c and
> > videodev2.h), and another patch that adds it to the uvcvideo driver
> > (drivers/media/common/uvc.c, include/linux/usb/uvc.h) ? We usually do so
> > to ease backporting.
>
> This can be great idea but uvc patch will fail compilation - 
> it's depends on V4L2_PIX_FMT_Y16I defined at videodev2.h

That's fine, you can send both patches as a series, with the patch
introducing the format first and the patch to the UVC code second. They
will be applied together, in that order.

> > > ---
> > >  .../userspace-api/media/v4l/pixfmt-y16i.rst   | 80 +++++++++++++++++++
> > >  .../userspace-api/media/v4l/yuv-formats.rst   |  1 +
> > >  drivers/media/common/uvc.c                    |  4 +
> > >  drivers/media/v4l2-core/v4l2-ioctl.c          |  1 +
> > >  include/linux/usb/uvc.h                       |  3 +
> > >  include/uapi/linux/videodev2.h                |  1 +
> > >  6 files changed, 90 insertions(+)
> > >  create mode 100644 Documentation/userspace-api/media/v4l/pixfmt-y16i.rst
> > > 
> > > diff --git a/Documentation/userspace-api/media/v4l/pixfmt-y16i.rst b/Documentation/userspace-api/media/v4l/pixfmt-y16i.rst
> > > new file mode 100644
> > > index 000000000000..3303b7832cdb
> > > --- /dev/null
> > > +++ b/Documentation/userspace-api/media/v4l/pixfmt-y16i.rst
> > > @@ -0,0 +1,80 @@
> > > +.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
> > > +
> > > +.. _V4L2-PIX-FMT-Y16I:
> > > +
> > > +**************************
> > > +V4L2_PIX_FMT_Y16I ('Y16I')
> > > +**************************
> > > +
> > > +Interleaved grey-scale image, e.g. from a stereo-pair
> > > +
> > > +
> > > +Description
> > > +===========
> > > +
> > > +This is a grey-scale image with a depth of 16 bits per pixel, but with
> > > +pixels from 2 sources interleaved and unpacked. Each pixel is stored
> > > +in a 32-bit word in the little-endian order. On a little-endian machine
> > > +these pixels can be deinterlaced using
> > > +
> > > +.. code-block:: c
> > > +
> > > +    __u8 *buf;
> > > +    left0 = 0xffff & *(__u16 *)buf;
> > > +    right0 = 0xffff & *((__u16 *)buf + 1);
> > 
> > I think this is a bit overkill. I would simply write
> > 
> > This is a grey-scale image with a depth of 16 bits per pixel, but with pixels
> > from 2 sources interleaved and unpacked. Each pixel is stored in a 16-bit word
> > in the little-endian order. The first pixel is from the left source.
> > 
> > > +
> > > +**Pixel unpacked representation.**
> > > +Left/Right pixels 16-bit unpacked - 16-bit for each interleaved pixel.
> > > +
> > > +.. flat-table::
> > > +    :header-rows:  0
> > > +    :stub-columns: 0
> > > +
> > > +    * - Y'\ :sub:`0L[7:0]`
> > > +      - Y'\ :sub:`0L[15:8]`
> > > +      - Y'\ :sub:`0R[7:0]`
> > > +      - Y'\ :sub:`0R[15:8]`
> > > +
> > > +**Byte Order.**
> > > +Each cell is one byte.
> > > +
> > > +.. flat-table::
> > > +    :header-rows:  0
> > > +    :stub-columns: 0
> > > +
> > > +    * - start + 0:
> > > +      - Y'\ :sub:`00Llow`
> > > +      - Y'\ :sub:`00Lhigh`
> > > +      - Y'\ :sub:`00Rlow`
> > > +      - Y'\ :sub:`00Rhigh`
> > > +      - Y'\ :sub:`01Llow`
> > > +      - Y'\ :sub:`01Lhigh`
> > > +      - Y'\ :sub:`01Rlow`
> > > +      - Y'\ :sub:`01Rhigh`
> > > +    * - start + 8:
> > > +      - Y'\ :sub:`10Llow`
> > > +      - Y'\ :sub:`10Lhigh`
> > > +      - Y'\ :sub:`10Rlow`
> > > +      - Y'\ :sub:`10Rhigh`
> > > +      - Y'\ :sub:`11Llow`
> > > +      - Y'\ :sub:`11Lhigh`
> > > +      - Y'\ :sub:`11Rlow`
> > > +      - Y'\ :sub:`11Rhigh`
> > > +    * - start + 16:
> > > +      - Y'\ :sub:`20Llow`
> > > +      - Y'\ :sub:`20Lhigh`
> > > +      - Y'\ :sub:`20Rlow`
> > > +      - Y'\ :sub:`20Rhigh`
> > > +      - Y'\ :sub:`21Llow`
> > > +      - Y'\ :sub:`21Lhigh`
> > > +      - Y'\ :sub:`21Rlow`
> > > +      - Y'\ :sub:`21Rhigh`
> > > +    * - start + 24:
> > > +      - Y'\ :sub:`30Llow`
> > > +      - Y'\ :sub:`30Lhigh`
> > > +      - Y'\ :sub:`30Rlow`
> > > +      - Y'\ :sub:`30Rhigh`
> > > +      - Y'\ :sub:`31Llow`
> > > +      - Y'\ :sub:`31Lhigh`
> > > +      - Y'\ :sub:`31Rlow`
> > > +      - Y'\ :sub:`31Rhigh`
> > > diff --git a/Documentation/userspace-api/media/v4l/yuv-formats.rst b/Documentation/userspace-api/media/v4l/yuv-formats.rst
> > > index 24b34cdfa6fe..78ee406d7647 100644
> > > --- a/Documentation/userspace-api/media/v4l/yuv-formats.rst
> > > +++ b/Documentation/userspace-api/media/v4l/yuv-formats.rst
> > > @@ -269,5 +269,6 @@ image.
> > >      pixfmt-yuv-luma
> > >      pixfmt-y8i
> > >      pixfmt-y12i
> > > +    pixfmt-y16i
> > >      pixfmt-uv8
> > >      pixfmt-m420
> > > diff --git a/drivers/media/common/uvc.c b/drivers/media/common/uvc.c
> > > index 9c0ba7a6c185..246fb6da5903 100644
> > > --- a/drivers/media/common/uvc.c
> > > +++ b/drivers/media/common/uvc.c
> > > @@ -120,6 +120,10 @@ static const struct uvc_format_desc uvc_fmts[] = {
> > >  		.guid		= UVC_GUID_FORMAT_Y12I,
> > >  		.fcc		= V4L2_PIX_FMT_Y12I,
> > >  	},
> > > +	{
> > > +		.guid		= UVC_GUID_FORMAT_Y16I,
> > > +		.fcc		= V4L2_PIX_FMT_Y16I,
> > > +	},
> > >  	{
> > >  		.guid		= UVC_GUID_FORMAT_Z16,
> > >  		.fcc		= V4L2_PIX_FMT_Z16,
> > > diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> > > index 6e7b8b682d13..49a17487e196 100644
> > > --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> > > +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> > > @@ -1314,6 +1314,7 @@ static void v4l_fill_fmtdesc(struct v4l2_fmtdesc *fmt)
> > >  	case V4L2_PIX_FMT_IPU3_Y10:	descr = "10-bit greyscale (IPU3 Packed)"; break;
> > >  	case V4L2_PIX_FMT_Y8I:		descr = "Interleaved 8-bit Greyscale"; break;
> > >  	case V4L2_PIX_FMT_Y12I:		descr = "Interleaved 12-bit Greyscale"; break;
> > > +	case V4L2_PIX_FMT_Y16I:		descr = "Interleaved 16-bit Greyscale"; break;
> > >  	case V4L2_PIX_FMT_Z16:		descr = "16-bit Depth"; break;
> > >  	case V4L2_PIX_FMT_INZI:		descr = "Planar 10:16 Greyscale Depth"; break;
> > >  	case V4L2_PIX_FMT_CNF4:		descr = "4-bit Depth Confidence (Packed)"; break;
> > > diff --git a/include/linux/usb/uvc.h b/include/linux/usb/uvc.h
> > > index 88d96095bcb1..1c16be20c966 100644
> > > --- a/include/linux/usb/uvc.h
> > > +++ b/include/linux/usb/uvc.h
> > > @@ -118,6 +118,9 @@
> > >  #define UVC_GUID_FORMAT_Y12I \
> > >  	{ 'Y',  '1',  '2',  'I', 0x00, 0x00, 0x10, 0x00, \
> > >  	 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
> > > +#define UVC_GUID_FORMAT_Y16I \
> > > +	{ 'Y',  '1',  '6',  'I', 0x00, 0x00, 0x10, 0x00, \
> > > +	 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
> > >  #define UVC_GUID_FORMAT_Z16 \
> > >  	{ 'Z',  '1',  '6',  ' ', 0x00, 0x00, 0x10, 0x00, \
> > >  	 0x80, 0x00, 0x00, 0xaa, 0x00, 0x38, 0x9b, 0x71}
> > > diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> > > index a8015e5e7fa4..d152027021d3 100644
> > > --- a/include/uapi/linux/videodev2.h
> > > +++ b/include/uapi/linux/videodev2.h
> > > @@ -793,6 +793,7 @@ struct v4l2_pix_format {
> > >  #define V4L2_PIX_FMT_S5C_UYVY_JPG v4l2_fourcc('S', '5', 'C', 'I') /* S5C73M3 interleaved UYVY/JPEG */
> > >  #define V4L2_PIX_FMT_Y8I      v4l2_fourcc('Y', '8', 'I', ' ') /* Greyscale 8-bit L/R interleaved */
> > >  #define V4L2_PIX_FMT_Y12I     v4l2_fourcc('Y', '1', '2', 'I') /* Greyscale 12-bit L/R interleaved */
> > > +#define V4L2_PIX_FMT_Y16I     v4l2_fourcc('Y', '1', '6', 'I') /* Greyscale 16-bit L/R interleaved */
> > >  #define V4L2_PIX_FMT_Z16      v4l2_fourcc('Z', '1', '6', ' ') /* Depth data 16-bit */
> > >  #define V4L2_PIX_FMT_MT21C    v4l2_fourcc('M', 'T', '2', '1') /* Mediatek compressed block mode  */
> > >  #define V4L2_PIX_FMT_MM21     v4l2_fourcc('M', 'M', '2', '1') /* Mediatek 8-bit block mode, two non-contiguous planes */

-- 
Regards,

Laurent Pinchart




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