ASoC: omap-mcbsp: Add PM QoS support for McBSP to prevent glitches

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We can get audio errors if hitting deeper idle states on omaps:

[alsa.c:230] error: Fatal problem with alsa output, error -5.
[audio.c:614] error: Error in writing audio (Input/output error?)!

This seems to happen with off mode idle enabled as power for the
whole SoC may get cut off between filling the McBSP fifo using DMA.
While active DMA blocks deeper idle states in hardware, McBSP
activity does not seem to do so.

Basing the QoS latency calculation on the FIFO size, threshold,
sample rate, and channels.

Based on the original patch by Tony Lindgren
Link: https://patchwork.kernel.org/patch/9305867/

Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
Signed-off-by: Liam Breck <kernel@networkimprov.net>
Tested-by: Tony Lindgren <tony@atomide.com>
Acked-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

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Matt Ranostay 2017-01-31 13:21:43 -08:00 • committed by Mark Brown

parent a5de5b74a5

commit 9834ffd1ec

2 changed files with 50 additions and 1 deletions

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3

sound/soc/omap/mcbsp.h

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48

sound/soc/omap/omap-mcbsp.c

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