Re: USB host isochronous transfer broken

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On Mon, Aug 13, 2012 at 12:01:52PM +0200, Ruben Jenster wrote:
> Hi,
> I need some help debugging a USB transfer problem on my raspberry pi.
> I know this is not a mainstream kernel issue but I would be glad if someone here can
> help me understand and debug the problem.
> The problem is that the DVB Transport stream recorded from a usb DVB stick (cinergy htc stick)
> attached to a usb hub which is attached to the raspberry pi is broken. 
> I use the latest media_build from against a 3.1.9 raspberry pi kernel.
> The same drivers from the media_build work perfectly with a 3.1.9 kernel on my thinkpad.
> [  126.162705] tda18271: performing RF tracking filter calibration
> [  128.056572] tda18271: RF tracking filter calibration complete
> [  128.057855] em28xx #0/2-dvb: Using 5 buffers each with 64 x 940 bytes
> [  129.052712] em28xx #0/2-dvb: ISO ERROR COUNT: 1.
> [  129.052743] em28xx #0/2-dvb: URB packet 0, status -4001 [Unknown].
> [  129.581352] em28xx #0/2-dvb: ISO ERROR COUNT: 1.
> [  129.581384] em28xx #0/2-dvb: URB packet 0, status -4001 [Unknown].
> [  129.872090] em28xx #0/2-dvb: ISO ERROR COUNT: 1.
> [  129.872122] em28xx #0/2-dvb: URB packet 0, status -4001 [Unknown].
> [  129.969224] em28xx #0/2-dvb: ISO ERROR COUNT: 1.
> [  129.969258] em28xx #0/2-dvb: URB packet 44, status -4001 [Unknown].
> My assumption is that the isochronous transfer is broken for the usb host driver.

After reading the code for the USB host driver for this hardware, and
reading the hardware data sheet, I'm amazed that any USB devices work on
this platform :)

I think you are right in that isoc just doesn't work on the codebase you
are trying to use, but I would try asking on the raspberry-pi kernel
mailing list to see if there are any updates that you can try out for
newer versions of the kernel and drivers, as I think a lot of work is
going on in this area last time I looked.

best of luck,

greg k-h
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