Re: [Qemu-devel] [0/7] USB UVC updates

[Brad Hards]

On Mon, 6 Jun 2011 07:32:32 PM Natalia Portillo wrote:
> I see it ok, have you tested nothing broken? (specially with the &s patch)
It doesn't work for me (before or after). The descriptor part (which I've now 
implemented) works OK (i.e. the guest can dump it), cheese runs in the guest 
but doesn't show images. luvcview opens but won't capture data. So I have more 
work to do.

> I should take more care with 's's in typos next time
I don't think this is the biggest problem :-)
 
> > The next change I propose to make is to rework the descriptors
> > and add constants / defines for magic numbers.
> 
> Yeah, there are a couple of magic numbers that can be added.
> Please note that most of the constants used in the descriptors should go
> in usb.h
I was planning to do the ones that are specific to usb-uvc.c in that file, and 
only (potentially) shared things like the interface descriptor stuff in usb.h

> Also take special care with the descriptors, the minimal change can break
> it very easily. The ideal solution would be to make the descriptors be
> dynamic depending on the host webcam capabilities.
I believe that part of the descriptor change may be associated with not 
reading data. I could easily have introduced a problem. I haven't finished 
debugging it, but I never see transactions to EP 2 (the isoc data endpoint).

> Bad thing the USB IF put the resolutions and formats in the descriptor,
> instead of in a query command.
Indeed, but like everything in USB device space, its designed down to minimise 
cost on (real) hardware.

Thanks.

Brad