[LAU] anyone checked out new USB reduced latency patch?

Clemens Ladisch clemens at ladisch.de
Sun Jun 6 20:16:33 CEST 2021

Chris Caudle wrote:
> I just saw that this is probably going in the 5.14 kernel:
> https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git/commit/?h=for-next&id=9ce650a75a3b262c90789b42aedee8fc2ee04d53
> "USB-audio driver behaves a bit strangely for the playback stream --
> namely, it starts sending silent packets at PCM prepare state while
> the actual data is submitted at first when the trigger START is kicked
> off. [...]
> This patch tries to revert the workaround and lets the URB submission
> starting at PCM trigger for the playback again.

Please note that this reduces only the time between the stream being
started and the first sample actually being played.  It does _not_
reduce the latency in the steady state, because the USB queue length
does not change.


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