Re: Kernel error "Unknown pixelformat 0x00000000" occurs when I start capture video

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

Em Wed, 9 Jan 2019 08:51:29 +0500
Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com> escreveu:

> I upgraded kernel to 5.0 rc1 and the error message  "Unknown
> pixelformat 0x00000000" are disappeared.
> 
> Instead I see not obvious message "uvcvideo: Non-zero status (-71) in
> video completion handler."

This is unrelated. Usually, you get -71 errors when there's a problem
with usb cabling. This is what it means:

	#define	EPROTO		71	/* Protocol error */

From Documentation/driver-api/usb/error-codes.rst:

``-EPROTO`` [#f1]_, [#f2]_	a) bitstuff error
				b) no response packet received within the
				   prescribed bus turn-around time
				c) unknown USB error

> Maybe in this case better to write "Video format XXX not supported" ?

The message about the lack of support for P010 is still there:

	[    5.218031] uvcvideo: Unknown video format 30313050-0000-0010-8000-00aa00389b71

The best solution would be to really convert this into something that
applications can benefit, e. g. exporting the P010 format to userspace.

> It would help quickly understand that is culprit here.
> 
> 
> --
> Best Regards,
> Mike Gavrilov.



Thanks,
Mauro