[alsa-devel] Query on Audio DMA using DMAEngine

Clemens Ladisch clemens at ladisch.de
Thu Jul 4 13:00:30 CEST 2013

Joel Fernandes wrote:
> On 07/01/2013 01:10 AM, Mike Looijmans wrote:
>> The trouble with the current davinci driver is that the IRQ handler has a
>> real-time requirement, it must finish before the next DMA block completes. This
>> causes most of the buffer overruns on heavily loaded systems.
> But how do you get around not calling snd_pcm_period_elapsed in a time-sensitive
> fashion?

To ensure that other stuff is completed first, snd_pcm_period_elapsed()
could be called later from a tasklet.  (snd_pcm_period_elapsed() calls
the .pointer callback, which could be another source of delays depending
on how much hardware accesses it does.)


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