Am 14.09.2011 08:25, schrieb Jean-Francois Moine:
On Tue, 13 Sep 2011 21:14:28 +0200
Frank Schäfer<fschaefer....@googlemail.com> wrote:
I have a question about the following code in gspca.c:
in function gspca_dev_probe(...):
...
/* the USB video interface must be the first one */
if (dev->config->desc.bNumInterfaces != 1
&& intf->cur_altsetting->desc.bInterfaceNumber != 0)
return -ENODEV;
...
Is there a special reason for not allowing devices with USB interface
index> 0 for video ?
I'm experimenting with a device that has the video interface at index 3
and two audio interfaces at index 0 and 1 (index two is missing !).
And the follow-up question: can we assume that all device handled by the
gspca-driver have vendor specific video interfaces ?
Then we could change the code to
...
/* the USB video interface must be of class vendor */
if (intf->cur_altsetting->desc.bInterfaceClass !=
USB_CLASS_VENDOR_SPEC)
return -ENODEV;
...
Hi Frank,
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.
Regards.
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 ?).
Regards,
Frank
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