Isochronous USB transfers on RPI?

[Jakob Alvermark]

On Thu, January 17, 2013 01:00, Oleksandr Tymoshenko wrote:
> On 1/16/2013 6:29 AM, Jakob Alvermark wrote:
>
>> Hi,
>>
>>
>> I see that there is code, I'm not just very good at reading and writing
>> it. :-)
>>
>> usbdump is quiet on the Pi On my laptop I can see ISOC packets when
>> using the same webcam and software so something is missing.
>
> I'm not familiar with webcam configuration on freebsd but
> do you have all the components setup on RPi? Kernel driver and/or userland
> bits?

The device is a video grabber with an analog video camera connected. The
software is entirely in userland, using libusb. Code is at
http://code.google.com/p/easycap-somagic-linux/
I works on my laptop (amd64 with ehci) and comparing output of usbdump
while  (trying) capturing video, ISOC is completely missing on RPi.


>>
>> /Jakob
>>
>>
>> On 16 jan 2013, at 13:19, Hans Petter Selasky wrote:
>>
>>
>>> On Wednesday 16 January 2013 10:25:38 Jakob Alvermark wrote:
>>>
>>>> Hi,
>>>>
>>>>
>>>> Maybe this should go to the usb list, but it is probably relevant
>>>> here as well. I have been playing with the Pi for a while now and
>>>> having great fun with FreeBSD. Great work gonzo and others! However,
>>>> I'd like to use a webcam with it. I learned that USB webcams use
>>>> isochronous transfers and the DWC OTG driver doesn't fully implement
>>>> it. (If I read the commit logs correctly)
>>>> What is missing and how can I help?
>>>>
>>>>
>>> Hi,
>>>
>>>
>>> The DWC OTG driver has not fully implemented isochronous. Using
>>> isochronous transfers will have a high CPU load impact, because 1000
>>> IRQ's (FS) or 8000
>>> IRQ's (HS) second will be needed to feed the FIFOs. However, if this
>>> is acceptable, code can be found in:
>>>
>>> sys/dev/usb/controller/dwc_otg.c
>>>
>>> --HPS
>>>
>>>
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>
>
>