P010 fourcc format support - Was: Re: Kernel error "Unknown pixelformat 0x00000000" occurs when I start capture video

[Mauro Carvalho Chehab <mchehab+samsung@kernel.org>]

Em Wed, 9 Jan 2019 14:19:00 +0200
Sakari Ailus <sakari.ailus@iki.fi> escreveu:

> On Tue, Jan 08, 2019 at 04:49:16PM -0200, Mauro Carvalho Chehab wrote:
> > Em Tue, 8 Jan 2019 21:11:41 +0500
> > Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com> escreveu:
> >   
> > > On Tue, 8 Jan 2019 at 20:57, Laurent Pinchart
> > > <laurent.pinchart@ideasonboard.com> wrote:  
> > > >
> > > > Thank you.
> > > >
> > > > Your device exposes five formats: YUY2 (YUYV), YV12 (YVU420), NV12, P010 and
> > > > BGR3 (BGR24). They are all supported by V4L2 and the uvcvideo driver except
> > > > for the P010 format. This would be easy to fix in the uvcvideo driver if it
> > > > wasn't for the fact that the P010 format isn't support by V4L2. Adding support
> > > > for it isn't difficult, but I don't have time to do this myself at the moment.
> > > > Would you consider volunteering if I guide you ? :-)
> > > >    
> > > 
> > > Sure, I'd be happy to help. What is required of me?  
> > 
> > It shouldn't be hard. 
> > 
> > First, you need to add the new format at include/uapi/linux/videodev2.h,
> > like this one:
> > 
> > 	#define V4L2_PIX_FMT_YUV420M v4l2_fourcc('Y', 'M', '1', '2') /* 12  YUV420 planar */
> > 
> > Please put it together with the other YUV formats.
> > 
> > As the fourcc "P010" was not used on Linux yet, you could use it,
> > e. g., something like:
> > 
> > 	#define V4L2_PIX_FMT_YUV_P10 v4l2_fourcc('P', '0', '1', '0') /* 10  YUV420 planar */
> > 
> > You need then to document it. Each V4L2 format should have a description, 
> > like this:
> > 
> > 	https://linuxtv.org/downloads/v4l-dvb-apis-new/uapi/v4l/pixfmt-yuv420m.html
> > 
> > This is generated via a text file (using ReST syntax). On the above example,
> > it is produced by this file:
> > 
> > 	https://git.linuxtv.org/media_tree.git/tree/Documentation/media/uapi/v4l/pixfmt-yuv420m.rst
> > 
> > Writing it would take a little more time, but, provided that you don't 
> > copy what's written from external docs, you could take a look at the
> > Internet for the P010 descriptions, and use the pixfmt-yuy420m.rst file
> > as the basis for a new pixfmt-p010.rst file.  
> 
> There is some work done on this but it's not finished; searching "P010" in
> Patchwork yields this:
> 
> <URL:https://patchwork.linuxtv.org/patch/39752/>

Good point! I'm c/c the author of it.

The actual patch for media is this one:

	https://patchwork.linuxtv.org/patch/39753/

It sounds that the author didn't sent any version after that.

The goal seemed to be to add P010 support at DRM for the rockchip driver.

specifically with regards to patch 2/3, the issues seemed to be:

	- some naming issues with the multiplane format variants;
	- a typo: simliar -> similar;
	- a comment about the usage of 1/2 UTF code (½). Not sure if
	  Sphinx will handle it well for both html and pdf outputs.
	  It should, but better to double check.

Ayaka,

There is a UVC media device that supports P010 device. We're discussing
about adding support for it on media. The full thread is at:

https://lore.kernel.org/linux-media/20190109121900.hbrpttmxz3gaotwx@valkosipuli.retiisi.org.uk/T/#m8c395156ca0e898e4c8b1e2c6309d912bc414804

We've seen that you tried to submit a patch series for DRM adding
support for it at the rockship driver. What's the status of such
series?

Thanks,
Mauro