Re: [RFC, PATCH] gspca pac7302: propagate footer to userspace

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Hi Németh,

On 01/24/2010 06:20 PM, Németh Márton wrote:
Hi,

I'm dealing with Labtec Webcam 2200 and I found that the pac7302 driver does not
forward the image footer information to userspace. This footer contains some information
which might be interesting to the userspace. What exactly this footer means is
not clear as of this writing, but it is easier to analyze the data in
userspace than in kernel space.

I modified the sd_pkt_scan() in order the footer is transfered to the userspace together
with the image. This, however, breaks the image decoding in libv4lconvert. This is
can be easily solved by passing the image buffer to v4lconvert_convert() truncated by
0x4f bytes.

What do you think the right way would be to transfer image footer to userspace?

I agree that in retrospect sending the footer to userspace is a good
idea, but see below.

Is it necessary to add a new V4L2_PIX_FMT_* format in order not to brake userspace
programs?


Yes that is the only sensible way I see to do this, which IMHO is a too high price
to pay for just getting this info out of the kernel while we are not doing anything
with it. Now if we actually find a good use for this in userspace, then I think
we can do this, but until then I think you need to do this with a local
patch.

Regards,

Hans
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