Re: [RFC 1/2] ASoC: dmaengine-pcm: Add support for querying DMAcapabilities

From: Vinod Koul
Date: Mon Jul 15 2013 - 13:36:31 EST


On Mon, Jul 15, 2013 at 06:26:43PM +0100, Mark Brown wrote:
> On Mon, Jul 15, 2013 at 06:42:10PM +0200, Lars-Peter Clausen wrote:
>
> > + hw.period_bytes_min = 16;
> > + hw.period_bytes_max = dma_caps.max_sg_len;
>
> We can't read the minimum period size from dmaengine? Seems like
> something might have a restriction other than 16 bytes here.
max would be how many list items the engine supports so queried therotical min
would be 1 byte, not sure how 16 bytes is assumed above but my guess is that if
engine is able to push min burst lengths which would be 1 and give you
interrupt. But seriously, that would not be practical. So this should be a
realistic limit which system can cope with.

~Vinod

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