Re: [PATCH 2/2] [media] v4l: Add 10-bits per channel YUV pixel formats

From: ayaka
Date: Mon Jan 02 2017 - 08:04:27 EST




On 01/02/2017 07:07 PM, Sakari Ailus wrote:
Hi,

On Mon, Jan 02, 2017 at 06:53:16PM +0800, ayaka wrote:

On 01/02/2017 05:10 PM, Sakari Ailus wrote:
Hi Randy,

Thanks for the patch.

On Mon, Jan 02, 2017 at 04:50:04PM +0800, Randy Li wrote:
The formats added by this patch are:
V4L2_PIX_FMT_P010
V4L2_PIX_FMT_P010M
Currently, none of driver uses those format, but some video device
has been confirmed with could as those format for video output.
The Rockchip's new decoder has supported those format for profile_10
HEVC/AVC video.

Signed-off-by: Randy Li <ayaka@xxxxxxxxxxx>
If the format resembles the existing formats but on a different bit depth,
it should be named in similar fashion.
Do you mean it would be better if it is called as NV12_10?
If it otherwise resembles NV12 but just has 10 bits per pixel, I think
NV12_10 is a good name for it.
The main reason I don't like it is that there is a various of software having used the P010 for this kind of pixel format. It would leadi a conflict between them(and I never saw it is used as NV12_10), as the P010 is more common to be used.
I left a problem unsolved for P010 in v4l2, P010 have two variant, little endian and big endian. Which could be easy identified in drm driver(there is a flag for all the big endian pixel format).

Could you also add ReST documentation for the format, please?
I will.
The common requirement for merging patches that change interfaces has been
that there's a user for that change. It'll still help you to get this
The kernel used in rockchip has supported that format in drm driver, but
just we don't have a agreement about the pixel format. As the Gstreamer and
some others would call it with a P010_ prefix, but Mark(rockchip's drm
author) prefer the something like NV12_10, that is why I sent out those
patches, I want the upstream decided its final name.
Ack.

I think we haven't really tried to unify the format naming in the past
between the two subsystems. If existing conventions exist on both regarding
this format, then it's probably better to follow those.

Cc Laurent as well.

reviewed now so the interface that the future hopefully-in-mainline driver
provides will not change.

---
include/uapi/linux/videodev2.h | 2 ++
1 file changed, 2 insertions(+)

diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
index 46e8a2e3..9e03f20 100644
--- a/include/uapi/linux/videodev2.h
+++ b/include/uapi/linux/videodev2.h
@@ -551,6 +551,7 @@ struct v4l2_pix_format {
#define V4L2_PIX_FMT_NV61 v4l2_fourcc('N', 'V', '6', '1') /* 16 Y/CrCb 4:2:2 */
#define V4L2_PIX_FMT_NV24 v4l2_fourcc('N', 'V', '2', '4') /* 24 Y/CbCr 4:4:4 */
#define V4L2_PIX_FMT_NV42 v4l2_fourcc('N', 'V', '4', '2') /* 24 Y/CrCb 4:4:4 */
+#define V4L2_PIX_FMT_P010 v4l2_fourcc('P', '0', '1', '0') /* 15 Y/CbCr 4:2:0, 10 bits per channel */
/* two non contiguous planes - one Y, one Cr + Cb interleaved */
#define V4L2_PIX_FMT_NV12M v4l2_fourcc('N', 'M', '1', '2') /* 12 Y/CbCr 4:2:0 */
@@ -559,6 +560,7 @@ struct v4l2_pix_format {
#define V4L2_PIX_FMT_NV61M v4l2_fourcc('N', 'M', '6', '1') /* 16 Y/CrCb 4:2:2 */
#define V4L2_PIX_FMT_NV12MT v4l2_fourcc('T', 'M', '1', '2') /* 12 Y/CbCr 4:2:0 64x32 macroblocks */
#define V4L2_PIX_FMT_NV12MT_16X16 v4l2_fourcc('V', 'M', '1', '2') /* 12 Y/CbCr 4:2:0 16x16 macroblocks */
+#define V4L2_PIX_FMT_P010M v4l2_fourcc('P', 'M', '1', '0') /* 15 Y/CbCr 4:2:0, 10 bits per channel */
/* three planes - Y Cb, Cr */
#define V4L2_PIX_FMT_YUV410 v4l2_fourcc('Y', 'U', 'V', '9') /* 9 YUV 4:1:0 */