State of Linux webcam support

Greg KH greg at
Mon Oct 1 16:18:06 UTC 2007

On Mon, Oct 01, 2007 at 11:05:38AM -0400, Ben Warren wrote:
> Hello,
> > I've got a UVC webcam (logitech sphere) over here let me know if I can help
> > with testing. Also talking about the logitech sphere, it has the ability to
> > turn left/right and up/down, currently it uses custom IOCTL's for this and so
> > do some other drivers which can drive camera's with the same feature, I believe
> > we need to add some standard ioctl's for this (including one to query for this
> > capability), so that userspace apps can use this feature without having to
> > write support for it for each driver seperately.
> > Hi,
> A bit OT, and I apologize.  Are ioctls still the preferred way to pass
> complex data between the kernel and user space?  In my embedded work I
> try to use sysfs wherever possible, but for more complicated
> transactions still use ioctls because the single-parameter nature of
> sysfs can be limiting.
> This just came to mind when Hans mentioned defining a standard
> interface.  Please don't misread this as a suggestion.  I'm just
> trying to get a feel for how people are doing things these days.

For the video-for-linux interface, yes, unfortunatly they are still the
preferred way due to a lot of legacy issues that are involved :(

But for anything else, you are correct, use sysfs whenever possible for
simple things, and only use an ioctl for more complex transaction-like
things.  Although for some transaction-like things, configfs works quite
well, you might want to look into that.

hope this helps,

greg k-h

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