[alsa-devel] [PATCH 19/19] ASoC: fsi: Add DMAEngine support

Lars-Peter Clausen lars at metafoo.de
Mon Feb 6 09:47:31 CET 2012

On 02/04/2012 07:40 PM, Vinod Koul wrote:
> And while at it, I believe for this use, terminate_all is too strong an
> API to be used, perhaps we should introduce a STOP call, which just
> aborts the current descriptor but doesn't free it, or possibly move to
> submitted state/queue. And yes terminate_all should used in scenarios
> like free callback.
> That way it should map properly to ALSA PCM operations.

Yes, a call that would allow us to reset/restart a transfer would be nice.
While we are at it: Another nice addition, which would be good for sound
drivers is a callback, which reports the transfer's current position in the
datastream. This allows us to implement a pointer callback with sub-period
granularity and also allow us to implement the 'no period wakeup' feature. A
lot of DMA controllers support reporting this, but as far as I can see there
is currently no way to export this information using dmaengine.

- Lars

More information about the Alsa-devel mailing list