Hi Daniel On 03/04/13 15:55, Michael Trimarchi wrote: > Hi Daniel > > On 03/04/13 12:23, Daniel Mack wrote: >> Hi David, >> >> On 03.04.2013 12:15, David Henningsson wrote: >>> Just to get your attention here on what seems to be an USB audio >>> regression. >>> >>> The bug is described in detail here: >>> >>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1136110?comments=all >>> >>> Quoting the bug: >>> >>> " >>> This bug seems to affect only a certain kind of hardware, which is >>> called "Asynchronous USB Digital Audio Codec (DAC)". It's said that such >>> a DAC hosts the clock itself (USB Device Host). An ordinary DAC, so >>> called "Synchronous USB DAC", uses the clock hosted by the mother board, >>> which is not affected by this bug. >>> >>> When this bug affects an asynchronous USB DAC, the audio played by the >>> DAC is constantly interrupted. The playback itself does not stop, but >>> the output becomes discontinous, filling with constant crackling noises, >>> destroying everything the DAC plays. >>> " >>> >>> According to the bug reporter, which seems to have done quite a bit of >>> research, this started between 3.8-rc6 and 3.8-rc7 as well as stable >>> kernels and the bug also lists a few commits which could be the cause, >>> none under sound/usb though. >> >> There were no relevant changes for snd-usb between the two versions >> mentioned. The only patches that come in mind in this time window are: >> >> 3e619d041 "USB: EHCI: fix bug in scheduling periodic split transfers" >> b09a61cc0 "USB: EHCI: fix for leaking isochronous data" > > This last one, doesn't give me any problem, just a memory leak and not a choppy > playback (tested on 48Khz, 96Khz, 192Khz 32bit on OMAP3 device) and I don't > think that it can be the reason of the problem. Sorry the comment was for a bug that is not included in this list and recently fixed. USB: EHCI: fix bug in iTD/siTD DMA pool allocation Michael > > http://www.m2tech.biz/hiface_dac.html > > Michael > > >> >> And they have both been back-ported to stable. Copied Alan for reference. >> >> Any chance some of the bug reporters could try and revert exactly those >> for testing? >> >> >> Thanks, >> Daniel >> >> _______________________________________________ >> Alsa-devel mailing list >> Alsa-devel@xxxxxxxxxxxxxxxx >> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel >> > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
