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From: Sekhar Nori <nsekhar@ti.com>
To: Dan Williams <dan.j.williams@intel.com>,
	Vinod Koul <vinod.koul@intel.com>
Cc: DMA Engine Mailing List <dmaengine@vger.kernel.org>,
	Linux DaVinci Mailing List
	<davinci-linux-open-source@linux.davincidsp.com>,
	Jon Ringle <jringle@gridpoint.com>,
	Alexander Holler <holler@ahsoftware.de>,
	Linux OMAP Mailing List <linux-omap@vger.kernel.org>,
	Joel Fernandes <joelf@ti.com>
Subject: Re: [PATCH 1/1] dma: edma: fix incorrect SG list handling
Date: Mon, 14 Apr 2014 14:01:11 +0530	[thread overview]
Message-ID: <534B9CCF.1070904@ti.com> (raw)
In-Reply-To: <1395208550-1603-1-git-send-email-nsekhar@ti.com>

Vinod,

On Wednesday 19 March 2014 11:25 AM, Sekhar Nori wrote:
> The code to handle any length SG lists calls edma_resume()
> even before edma_start() is called. This is incorrect
> because edma_resume() enables edma events on the channel
> after which CPU (in edma_start) cannot clear posted
> events by writing to ECR (per the EDMA user's guide).
> 
> Because of this EDMA transfers fail to start if due
> to some reason there is a pending EDMA event registered
> even before EDMA transfers are started. This can happen if
> an EDMA event is a byproduct of device initialization.
> 
> Fix this by calling edma_resume() only if it is not the
> first batch of MAX_NR_SG elements.
> 
> Without this patch, MMC/SD fails to function on DA850 EVM
> with DMA. The behaviour is triggered by specific IP and
> this can explain why the issue was not reported before
> (example with MMC/SD on AM335x).
> 
> Tested on DA850 EVM and AM335x EVM-SK using MMC/SD card.
> 
> Cc: stable@vger.kernel.org # v3.12.x+
> Cc: Joel Fernandes <joelf@ti.com>
> Acked-by: Joel Fernandes <joelf@ti.com>
> Tested-by: Jon Ringle <jringle@gridpoint.com>
> Tested-by: Alexander Holler <holler@ahsoftware.de>
> Reported-by: Jon Ringle <jringle@gridpoint.com>
> Signed-off-by: Sekhar Nori <nsekhar@ti.com>

Looks like this patch is not in mainline still?

Thanks,
Sekhar

  reply	other threads:[~2014-04-14  8:31 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-19  5:55 [PATCH 1/1] dma: edma: fix incorrect SG list handling Sekhar Nori
2014-04-14  8:31 ` Sekhar Nori [this message]
2014-04-14  8:57   ` Vinod Koul
2014-04-14  9:09     ` Sekhar Nori

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