Re: USB mini-summit at LinuxCon Vancouver

From: Mauro Carvalho Chehab
Date: Thu Aug 11 2011 - 07:20:23 EST

Em 11-08-2011 05:57, Jean-Francois Moine escreveu:
> On Wed, 10 Aug 2011 17:14:05 -0300
> Mauro Carvalho Chehab <mchehab@xxxxxxxxxxxxx> wrote:
>>> -- moving the kernel webcam drivers out of the kernel and doing with these
>>> cameras _everything_ including webcam function through libusb. I myself do
>>> not have the imagination to be able to figure out how this could be done
>>> without a rather humongous amount of work (for example, which streaming
>>> apps that are currently available would be able to live with this?) but
>>> unless I misunderstand what he was saying, Greg K-H seems to think that
>>> this would be the best thing to do.
>> I also don't think that this a good alternative. As Hans V. pointed, one of
>> our long term targets is to create per-sensor I2C drivers that are independent
>> from the bridges. Also, moving it to userspace would require lots of work
>> with the duplication of V4L and gspca core into userspace for the devices
>> that would be moved, and may have some performance impacts.
> If only gspca subdrivers are concerned, moving them to usespace should
> be easy: only the gspca main has to be rewritten, and its best place is
> in the v4l library.

It would end by having two userspace drivers, as the data access driver is
at libgphoto2. So, the problem will just be moved to userspace. You'll
additionally need to deal with conflicts between kernelspace ALSA driver
and userspace video driver.


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