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

Alan Stern stern at rowland.harvard.edu
Thu Apr 18 18:42:00 CEST 2013

On Wed, 17 Apr 2013, Joe Rayhawk wrote:

> Small buffer/period sizes on usb audio playback though UHCI works fine on v3.7 but causes audio discontinuities/delays on v3.8 and v3.9-rc7.
> I've bisected the behavior down to
>     c44b225077bb1fb25ed5cd5c4f226897b91bedd4
>     'UHCI: implement new semantics for URB_ISO_ASAP'
> Tested on two UHCI hosts and three usb-audio devices, all from different vendors.

Can you provide a usbmon trace showing the problems?  And maybe also a 
similar trace made under a 3.7 kernel, where the problem doesn't occur?

Alan Stern

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