[alsa-devel] [PATCH 3/3] ASoC: omap-mcbsp: Add period size protection mode

Peter Ujfalusi peter.ujfalusi at ti.com
Wed Mar 21 09:23:31 CET 2012

On 03/20/2012 06:15 PM, Grazvydas Ignotas wrote:
> I wouldn't really call them broken, it's enough to set period size to
> 512 with smaller start_threshold (something like 50ms) to have
> problems, those parameters are perfectly valid for a program trying to
> achieve low latency.

Where this 50ms comes from?
The McBSP2 FIFO length is:
48KHz/mono:     26.66ms
48KHz/stereo:   13.33ms
44.1KHz/mono:   29.02ms
44.1KHz/stereo: 14.51ms
8Khz/mono:      160ms
8Khz/stereo:    80ms

Does Pandora uses 8Khz?

The same thing applies to the start_threshold as to the period size. It
has to be bigger than the FIFO size.

> It's a shame this still won't work out-of-the box, but at least there
> will be some solution.

Defaulting this behavior would break other distributions for OMAP
platforms. I know, Pandora is bitten by this, but MeeGo, ubuntu, Linaro
is fine (as far as I know).


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