[alsa-devel] [PATCH 2/2] ASoC: omap: Stop DMA re enabling in self linkage mode

Peter Ujfalusi peter.ujfalusi at nokia.com
Tue Dec 7 15:38:35 CET 2010

On Tuesday 07 December 2010 16:05:12 ext Mark Brown wrote:
> On Tue, Dec 07, 2010 at 11:17:26AM +0200, Peter Ujfalusi wrote:
> > I have not seen this happening on OMAP2/3, or at least I'm not aware of
> > it. Is this problem OMAP4 only?
> > Do you know if this happens on playback, capture or in both direction?
> > Is it worth to do this workaround only on OMAP4?
> Given that the patch should cause at most a single read from a register
> when tearing down DMA if it's not required I'd guess it's safer to just
> unconditionally enable the workaround on the off chance that it's just
> reallly rare rather than not needed?

Sure, it is a single read to a register, but generally I'm a bit nervous, when 
we have a while loop without timeout counter.
In theory we could have infinite loop, if the HW has a bad day...
This could be safe on all OMAP platforms, but I think it has been only tested on 
If this could happen, than IMHO it has to be handled by the omap_stop_dma, since 
other drivers could be hit by the same problem (there might be ERRATA for it 
already for OMAP4).


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