Am 16.09.2011 08:33, schrieb Jean-Francois Moine:
On Thu, 15 Sep 2011 23:46:57 +0200
Frank Schäfer<fschaefer.oss@xxxxxxxxxxxxxx> wrote:
For webcam devices, the interface class is meaningful only when set to
USB_CLASS_VIDEO (UVC). Otherwise, I saw many different values.
Does that mean that there are devices out in the wild that report for
example USB_CLASS_WIRELESS_CONTROLLER for the video interface ???
For video on a particular interface, the subdriver must call the
function gspca_dev_probe2() as this is done in spca1528 and xirlink_cit.
Hmm, sure, that would work...
But wouldn't it be better to improve the interface check and merge the
two probing functions ?
The subdrivers can decide which interfaces are (not) probed and the
gspca core does plausability checks (e.g. bulk/isoc endpoint ? usb class ?).
Generally, the first interface is the video device, and the function
gspca_dev_probe() works well enough.
The function gspca_dev_probe2() is used by only 2 subdrivers and the
way to find the correct interface is not easy. For example, the webcam
047d:5003 (subdriver spca1528) has 3 interfaces (class vendor specific).
The 1st one has only one altsetting with only one interrupt endpoint,
the 2nd one has 8 altsettings, each with only one isochronous endpoint,
and the last one has one altsetting with 3 endpoints (bulk in, bulk out
and interrupt). At the first glance, it is easy to know the right
interface, but writing generic code to handle such webcams seems rather
complicated.
I didn't want to say that it is easy to know the right interface. It is
definitely not.
But I think we could do it better than we currently do.
Anyway, it seems there is no interest in such a patch.
Thanks for you explanations.
So, if your webcam is in the 99.99% which use the interface 0, use
gspca_dev_probe(), otherwise, YOU know the right interface, so, call
gspca_dev_probe2().
Isn't it also possible that we don't know the right interface and it is
not interface 0 ? ;-)
Regards,
Frank
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