Re: g_webcam Isoch high bandwidth transfer

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

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Hi,

Bin Liu <b-liu@ti.com> writes:
> On Fri, Sep 23, 2016 at 10:49:57AM +0300, Felipe Balbi wrote:
>> 
>> Hi,
>> 
>> Bin Liu <b-liu@ti.com> writes:
>> > +Fengwei Yin per his request.
>> >
>> > On Thu, Sep 22, 2016 at 10:48:40PM +0300, Felipe Balbi wrote:
>> >> 
>> >> Hi,
>> >> 
>> >> Bin Liu <b-liu@ti.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
>
> Right, on mainline kernel (I tested 4.8.0-rc7) g_webcam is broken with
> DWC3, g_webcam does not enumerate on the host. But it works on v4.4.21.

There aren't that many changes related to g_webcam though.

$ git log --oneline --no-merges v4.4..HEAD -- drivers/usb/gadget/function/f_uvc.c drivers/usb/gadget/legacy/webcam.c drivers/usb/gadget/function/uvc*
4fbac5206afd usb: gadget: uvc: Add missing call for additional setup data
bd610c5aa9fc usb: gadget: uvc: Fix return value in case of error
36c0f8b32c4b [media] vb2: replace void *alloc_ctxs by struct device *alloc_devs
1ae1602de028 configfs: switch ->default groups to a linked list
d6dd645eae76 [media] media: videobuf2: Move timestamp to vb2_buffer
df9ecb0cad14 [media] vb2: drop v4l2_format argument from queue_setup
0aecfc1b359d usb: gadget: composite: remove redundant bcdUSB setting in legacy

>> uvc-gadget keeps printing this error message:
>> 
>>  159         if ((ret = ioctl(dev->fd, VIDIOC_DQBUF, &buf)) < 0) {
>>  160                 printf("Unable to dequeue buffer: %s (%d).\n", strerror(errno),
>>  161                         errno);
>>  162                 return ret;
>>  163         }
>
> I removed this printf, since it floods the console if start uvc-gadget
> before connect to the host.

fair enough

> BTY, you don't have to start uvc-gadget first then connect usb cable. I
> keep the cable always connected.

good to know. Thanks

-- 
balbi

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