On Wed, 30 Jun 2004, John Que wrote:

> Second:
> I did try to add usb_set_interface(pdev->udev, 0, 0)
> before usb_set_interface(pdev->udev, 0, 1);  and it still hangs in the same 
> place.

You said before that the driver was hanging in pwc_video_ioctl()'s 
VIDIOCSYNC handler, but when you added printk() statements there none of 
them got triggered.  Doesn't that indicate that the hang occurs somewhere 
else, not where you thought?


> But still usb_pipeendpoint() and pdev->vendpoint returns 5 as before;
> I do not understand from where is this "5" , in all three cases: when using 
> alternate
> setting 1 and 2 and 3. In fact I do not understand its meaning.

Every USB device can have up to 30 endpoints, and each endpoint is 
assigned a number between 1 and 15 (an input endpoint and an output 
endpoint may share the same number).  But the numbers don't have to be 
consecutivee.  So there's no reason why a camera with 2 endpoints might 
not choose to number them 2 and 5.


> Fourth :
> Gerald said:
> >Try getting the device status
> >just after changing the setting to see if the setting that you choose
> >did not stall the camera.
> 
> If you can be more specific: what and how should I do it (which method
> to call and what to check ) in order to find out if the setting that I 
> choose
> did not stall the camera ,I will be thankful; I am quite a newbie in USB 
> matters.

One test you could do is simply to repeat the usb_set_interface() call; 
just issue the same call twice in a row.  If the second one succeeds then 
the first one did not totally hang the camera.

Alan Stern



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