Which Userland Interface for USB Video Class Driver?
Hans Petter Selasky
hselasky at c2i.net
Wed Sep 24 06:45:59 UTC 2008
On Tuesday 23 September 2008, Fritz Katz wrote:
> On Monday, September 22, 2008 5:33 AM, Intron <intron(at)intron(dot)ac>
> > I would write/port a driver for USB video class for FreeBSD's
> > new USB stack (usb2). OpenBSD and NetBSD both has had their
> > own implementations for the device class as some people referred
> > to recently. But which userland interface, bktr(4) or V4L2, should
> > I use for the driver?
> We've only got two choices:
> -- bktr is dead,
> -- and V4L2 doesn't exist.
> bktr is a dead end. The Brooktree company no longer exists.
> Conexant stopped making bktr chips years ago.
> It only supports analog -- analog is a dead end too.
> Instead, look at Jason Harmening's work on cx88 support:
> ... that's the future.
> V4L2 has a well defined interface, and numerous applications
> already support it. It's not tied to any particular hardware,
> company, or chip so it's not going to die like bktr did.
> IMHO, V4L2 should be the future for BSDs as well.
> Implementing a V4L2-IOCTL interface would be a moderately difficult
> but very rewarding project.
Maybe you will find the following file useful:
Regarding porting, there is not much you need to do. Simply make sure that you
handle the IOCTLs directly in the video driver.
> > I have noticed that Julian has done some work for V4L2:
> > But I wonder how soon Julian's code can be committed into
> > the main source tree. I wouldn't see the driver sleeps outside
> > the main source tree.
> Looks like no activity in that tree since 2006/08/24 -- I don't see it
> being committed anytime soon.
> I've started a project to bring V4L2 to BSDs here:
> -- Fritz Katz.
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