[alsa-devel] [PATCH 09/18] ASoC: Samsung: Do not queue cyclic buffers multiple times
tomasz.figa at gmail.com
Wed Aug 28 10:23:34 CEST 2013
On Wednesday 28 of August 2013 09:06:27 Linus Walleij wrote:
> On Sun, Aug 11, 2013 at 7:59 PM, Tomasz Figa <tomasz.figa at gmail.com>
> > The legacy S3C-DMA API required every period of a cyclic buffer to be
> > queued separately. After conversion of Samsung ASoC to Samsung DMA
> > wrappers somebody made an assumption that the same is needed for DMA
> > engine API, which is not true.
> > In effect, Samsung ASoC DMA code was queuing the whole cyclic buffer
> > multiple times with a shift of one period per iteration, leading to:
> > a) severe memory waste - up to 13x times more DMA transfer
> > descriptors
> > are allocated than needed,
> > b) possible memory corruption, because further cyclic buffers were
> > out
> > of the original buffers, due to the offset.
> > This patch fixes this problem by making the legacy S3C-DMA API use the
> > same semantics as DMA engine (the whole cyclic buffer is enqueued at
> > once) and modifying users of Samsung DMA wrappers in cyclic mode to
> > behave appropriately.
> > Signed-off-by: Tomasz Figa <tomasz.figa at gmail.com>
> > Acked-by: Linus Walleij <linus.walleij at linaro.org>
> If patch 1 thru 9 are uncontroversial now, maybe Vinod can apply
> these for v3.12 so we can get less noise and risk of collissions
> in the next merge window?
> Just an idea.
That would be nice, leaving only Samsung-specific patches for the next
(That would be patches 1 to 8, though, as 9 is a patch for ASoC that could
be picked up by Mark Brown independently.)
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