linux-kernel - Re: [PATCH] usbvision: remove (broken) image format conversion

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Date:	Tue, 26 Apr 2011 14:33:20 +0200
From:	"Hans Verkuil" <hverkuil@...all.nl>
To:	"Hans de Goede" <hdegoede@...hat.com>
Cc:	"Ondrej Zary" <linux@...nbow-software.org>,
	"Joerg Heckenbach" <joerg@...kenbach-aw.de>,
	"Dwaine Garden" <dwainegarden@...ers.com>,
	linux-media@...r.kernel.org,
	"Kernel development list" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usbvision: remove (broken) image format conversion

> Hi,
>
> On 04/26/2011 10:30 AM, Ondrej Zary wrote:
>> On Tuesday 26 April 2011, you wrote:
>>> On Monday, April 25, 2011 23:23:17 Ondrej Zary wrote:
>>>> The YVU420 and YUV422P formats are broken and cause kernel panic on
>>>> use.
>>>> (YVU420 does not work and sometimes causes "unable to handle paging
>>>> request" panic, YUV422P always causes "NULL pointer dereference").
>>>>
>>>> As V4L2 spec says that drivers shouldn't do any in-kernel image format
>>>> conversion, remove it completely (except YUYV).
>>>
>>> What really should happen is that the conversion is moved to
>>> libv4lconvert.
>>> I've never had the time to tackle that, but it would improve this
>>> driver a
>>> lot.
>>
>> Depending on isoc_mode module parameter, the device uses different image
>> formats: YUV 4:2:2 interleaved, YUV 4:2:0 planar or compressed format.
>>
>> Maybe the parameter should go away and these three formats exposed to
>> userspace?
>
> That sounds right,
>
>> Hopefully the non-compressed formats could be used directly
>> without any conversion. But the compressed format (with new
>> V4L2_PIX_FMT_
>> assigned?) should be preferred (as it provides much higher frame rates).
>> The
>> code moved into libv4lconvert would decompress the format and convert
>> into
>> something standard (YUV420?).
>
> Correct.
>
>>
>>> Would you perhaps be interested in doing that work?
>>
>> I can try it. But the hardware isn't mine so my time is limited.
>>
>
> If you could give it a shot that would be great. I've some hardware to
> test this with (although I've never actually tested that hardware), so
> I can hopefully pick things up if you cannot finish things before you
> need to return the hardware.

I can also test this.

Regards,

       Hans

>
> Thanks & Regards,
>
> Hans
>


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