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Re: usb isochronous devices

Fettahlioglu, Mahmut wrote:
> Hi,
> I am trying to use an iMic USB sound card with the Etrax MCM. The
> major/minor numbers are registered properly, however when I try to read
> or
> write to/from the sound driver I eventually get kernel panics or
> apparently
> infinite loops. Before this lots of either
>  - usb-host.c: assert failed at line 1679
>  - usb-host.c: Ignoring NULL urb, or
>  - usb-host.c: Out of synch? Previous frame = 1880, current frame = 1889
> (numbers vary, the current always seems to be previous+9 rather than the
> expected previous+5).
> warning messages are printed out.

If you have the serial debug port enabled, try and disable it and 
capture the debug printouts via /proc/kmsg instead.

> I have tried both kernel 4.2.19 and 4.2.22 with usbhost.c version 1.19.
> Before going further with my testing/debugging I thought it would be a
> good
> idea to get your feedback on this as well. Are there any known issues
> with
> isochronous devices?

Isochronous in traffic should work fine, out traffic is not implemented 
(though I see now that the driver fails to indicate this properly). 
Please contact Fredrik Norrman (fredrik.norrman@xxxxxxx.com) if this is 
something you'd want implemented.

Orjan Friberg
Axis Communications