ASoC: davinci-mcasp: Add overrun/underrun event handling

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An underrun (playback) event occurs when the serializer transfer
data from the XRBUF buffer to the XRSR shift register, but the
XRBUF hasn't been filled. Similarly, the overrun (capture) event
occurs when data from the XRSR shift register is transferred to
the XRBUF but it hasn't been read yet.

These events are handled as XRUN events that cause the pcm to stop.
The stream has to be explicitly restarted by the userspace which
ensures that after stopping/starting McASP the data transfer is
aligned with DMA. The other possibility was to internally stop and
start McASP without DMA even knowing about it.

Signed-off-by: Misael Lopez Cruz <misael.lopez@ti.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

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Misael Lopez Cruz 2014-11-12 16:38:05 +02:00 • committed by Mark Brown

parent 18a4f55756

commit a7a3324a60

3 changed files with 136 additions and 1 deletions

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2

Documentation/devicetree/bindings/sound/davinci-mcasp-audio.txt

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124

sound/soc/davinci/davinci-mcasp.c

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11

sound/soc/davinci/davinci-mcasp.h

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