[alsa-devel] [PATCH 1/2] powerpc: add platform registration for ALSA SoC drivers
broonie at opensource.wolfsonmicro.com
Tue Apr 27 23:11:18 CEST 2010
On Tue, Apr 27, 2010 at 04:03:27PM -0500, Timur Tabi wrote:
[Reflowing the text into 80 columns again]
> Mark Brown wrote:
> > It's entirely possible that if the board designer intended the verious
> > SSIs to be used in concert they've done something like cross wire the
> > clocks which creates a board-specific interrelationship that needs to be
> > dealt with.
> Fine, but I don't see how that can be handled with the current code.
> Each SSI is independent, and audio is streamed to it via DMA. The
> current SSI driver would need to be completely rewritten in order to
> initiate both DMA operations simultaneously. The clocking is the least
> of my problems.
I believe the usual technique is to start the DMA then clock the bus -
data doesn't flow over the bus until the clock appears and that appears
everywhere simultaneously. Obviously some hardware really doesn't like
having the DMA blocked like that, but not all.
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