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

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Message-ID: <5163BAA8.7040502@ti.com>
Date:	Tue, 9 Apr 2013 12:22:24 +0530
From:	Santosh Shilimkar <santosh.shilimkar@...com>
To:	Tony Lindgren <tony@...mide.com>
CC:	Russell King - ARM Linux <linux@....linux.org.uk>,
	Peter Ujfalusi <peter.ujfalusi@...com>,
	Vinod Koul <vinod.koul@...el.com>, Dan Williams <djbw@...com>,
	Jarkko Nikula <jarkko.nikula@...mer.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

On Monday 08 April 2013 10:45 PM, Tony Lindgren wrote:
> * 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.
> 
Am curious on your suggestion. DMA engine patches are going via Vinod
Koul's tree so I think the $subject patch should follow the same
tree, No ?

Peter, if you plan to re-send, feel free to add my ack.


Regards,
Santosh

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