linux-kernel - Re: [RFC v2] dmaengine: omap-dma: Start DMA without delay for cyclic channels

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Date:	Mon, 8 Apr 2013 10:15:19 -0700
From:	Tony Lindgren <tony@...mide.com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
Cc:	Peter Ujfalusi <peter.ujfalusi@...com>,
	Vinod Koul <vinod.koul@...el.com>, Dan Williams <djbw@...com>,
	Jarkko Nikula <jarkko.nikula@...mer.com>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Felipe Balbi <balbi@...com>, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	Peter Meerwald <pmeerw@...erw.net>
Subject: Re: [RFC v2] dmaengine: omap-dma: Start DMA without delay for
 cyclic channels

* Russell King - ARM Linux <linux@....linux.org.uk> [130408 10:15]:
> On Mon, Apr 08, 2013 at 09:11:04AM +0200, Peter Ujfalusi wrote:
> > Russell,
> > 
> > On 04/03/2013 01:17 PM, Peter Ujfalusi wrote:
> > > cyclic DMA is only used by audio which needs DMA to be started without a
> > > delay.
> > > If the DMA for audio is started using the tasklet we experience random
> > > channel switch (to be more precise: channel shift).
> > > 
> > > Reported-by: Peter Meerwald <pmeerw@...erw.net>
> > > Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
> > > ---
> > > Hi Russell,
> > > 
> > > Instead of removing the tasklet we can identify the DMA channel used by audio
> > > based on the cyclic flag of the channel.
> > > I think this can be used as a short term solution to fix the audio channel shift
> > > issue and later when we have the dynamic DMA channel allocation we can adjust
> > > the code.
> > 
> > Could you, please look at this patch?
> 
> Now that I'm back from a short 4 day break, then yes, and the answer is
> that it's fine.  Who's handling the patch?

I suggest Peter resend the patch with also Grant + Linus W cc:d so
they can queue it unless there are other related patches pending
somewhere else.

Regards,

Tony
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