Re: g_webcam Isoch high bandwidth transfer

[Felipe Balbi <felipe.balbi@linux.intel.com>]

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Hi,

Laurent Pinchart <laurent.pinchart@ideasonboard.com> writes:
> Hi Felipe,
>
> On Friday 23 Sep 2016 11:27:26 Felipe Balbi wrote:
>> yfw <nh26223@gmail.com> writes:
>> >>>>>> Here's one that actually compiles, sorry about that.
>> >>>>> 
>> >>>>> No worries, I was sleeping ;-)
>> >>>>> 
>> >>>>> I will test it out early next week. Thanks.
>> >>>> 
>> >>>> meanwhile, how about some instructions on how to test this out myself?
>> >>>> How are you using g_webcam and what are you running on host side? Got a
>> >>>> nice list of commands there I can use? I think I can get to bottom of
>> >>>> this much quicker if I can reproduce it locally ;-)
>> >>> 
>> >>> On device side:
>> >>> - first patch g_webcam as in my first email in this thread to enable
>> >>>   640x480@30fps;
>> >>> - # modprobe g_webcam streaming_maxpacket=3072
>> >>> - then run uvc-gadget to feed the YUV frames;
>> >>> 	http://git.ideasonboard.org/uvc-gadget.git
>> >> 
>> >> as is, g_webcam never enumerates to the host. It's calls to
>> >> usb_function_active() and usb_function_deactivate() are unbalanced. Do
>> >> you have any other changes to g_webcam?
>> > 
>> > With uvc function gadget driver, user daemon uvc-gadget must be started
>> > before connect to host. Not sure whether g_webcam has same requirement.
>> 
>> f_uvc.c should be handling that by means for usb_function_deactivate().
>> 
>> I'll try keeping cable disconnected until uvc-gadget is running.
>
> Things might have changed since we've discussed the issue several years ago, 
> but back then at least the musb UDC started unconditionally connected.

That's kinda of not the case anymore. We deactivate during function
registration if a certain flag is set.

-- 
balbi

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