[alsa-devel] [PATCH] ASoC: omap-mcbsp: Add PM QoS support for McBSP to prevent glitches

[Tony Lindgren]

* Peter Ujfalusi <peter.ujfalusi at ti.com> [160907 07:32]:
> On 09/06/2016 11:16 PM, Tony Lindgren wrote:
> > Makes sense. Do you have a formula or updated patch I can test here?
> > Then we can add comments about the possible unaccounted latencies that
> > can be worked out as needed.
> 
> Not yet, but I'll try to come up with something in the coming days.

OK

> btw: I have tried the idle off on beagbeboard-xm with audio, but even w/o the
> qos it is not triggering. w/o audio I hit off but if audio is running, not.

OK yeah figured it out you need to comment out the watch -n5 command
as that keeps the serial console busy :) I was doing it over ssh earlier
on the torpedo board.

> btw2: if you set the qos to 30ms and set the mcbsp2 threshold to 1024 (or
> leave it as default) do you have audio glitches? I think if we hit C6 we
> should not be able to wake up in time...

Not that I've noticed at least with the default fifo size. How can
I force the threshold to 1024? I tried changing pkt_size for
omap_mcbsp_set_threshold but not getting any audio.

Regards,

Tony