Re: [PATCH] dmaengine: pl330: Really fix choppy sound because of wrong residue calculation

[Lars-Peter Clausen]

On 06/30/2015 06:51 AM, Krzysztof KozÅowski wrote:
> 2015-06-30 13:14 GMT+09:00 Vinod Koul <vinod.koul@xxxxxxxxx>:
> > On Mon, Jun 22, 2015 at 11:14:42AM +0900, Krzysztof KozÅowski wrote:
> > > 2015-06-15 23:00 GMT+09:00 Krzysztof Kozlowski <k.kozlowski.k@xxxxxxxxx>:
> > > > When pl330 driver was used during sound playback, after some time or
> > > > after a number of plays the sound became choppy or totally noisy. For
> > > > example on Odroid XU3 board the first four executions of aplay with
> > > > small WAVE worked fine, but fifth was unrecognizable with errors:
> > > >          $ aplay /usr/share/sounds/alsa/Front_Right.wava
> > > >          underrun!!! (at least 0.095 ms long)
> > > >
> > > > Issue was caused by wrong residue reported by pl330 driver to
> > > > pcm_dmaengine for its cyclic dma transfers.
> > > >
> > > > The pl330_tx_status(), residue reporting function, used a "last" flag in
> > > > a descriptor to indicate that there is no more data to send.
> > > >
> > > > The pl330_tx_submit() iterated over descriptors trying to remove this
> > > > flag from them and then mark last descriptor as "last".  However when
> > > > iterating it actually removed the flag not from descriptors but always
> > > > from last of it (and then reset it). Thus effectively once some
> > > > descriptor was marked as last, then it stayed like this forever causing
> > > > residue to be reported too low.
> > > >
> > > > Signed-off-by: Krzysztof Kozlowski <k.kozlowski.k@xxxxxxxxx>
> > > > Fixes: aee4d1fac887 ("dmaengine: pl330: improve pl330_tx_status() function")
> > > > Cc: <stable@xxxxxxxxxxxxxxx>
> > > > Reported-by: gabriel@xxxxxxxxx
> > > > Suggested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> > >
> > > Gabriel, could you give this patch a try? It helped for my Odroid XU3,
> > > which has the same audio codec. Nevertheless it would be great to hear
> > > that it solves the initial bug report.
> >
> > So is there a word on  what finally fixes this
>
> This fixes sound issue on my Odroid XU3 board, which is good. My board
> has the same audio codec and DMA driver as the board used by Gabriel
> so there is high chance that his issue is also fixed.
>
> However it is sad that I did not receive any reviews or tests from
> anyone, apparently no one cares enough about it :) .

I care, I've had it in applied to my local tree for a while now. Without it 
audio does not work.

Tested-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
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