[alsa-devel] BUG: USB audio discontinuities with 'UHCI: implement new semantics for URB_ISO_ASAP'

Clemens Ladisch clemens at ladisch.de
Tue Apr 23 17:09:35 CEST 2013


Alan Stern wrote:
> On Tue, 23 Apr 2013, Clemens Ladisch wrote:
>> Why is having a queue of two URB with one packet each suddenly not
>> allowed?
>
> It _is_ allowed when URB_ISO_ASAP is clear.  I have never fully
> understood why the audio driver sets that flag.  By setting it, you are
> telling the host controller driver that you are willing to give up
> reduced latency in order to avoid underruns.

This flag was needed to avoid having to set urb->start_frame.

With the changed queueing API, the audio driver needs to change too.
I'll look into this ...


Regards,
Clemens
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