On 03/18/2014 10:28 AM, Vinod Koul wrote: > On Mon, Mar 17, 2014 at 09:14:14AM -0400, Jon Ringle wrote: >> On Mon, 17 Mar 2014, Sekhar Nori wrote: >> >>> Hi Jon, >>> >>> On Monday 17 March 2014 06:28 PM, Jon Ringle wrote: >>>> >>>> On Mon, 17 Mar 2014, 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@xxxxxxxxxxxxxxx> # v3.12.x+ >>>>> Cc: Joel Fernandes <joelf@xxxxxx> >>>>> Reported-by: Jon Ringle <jringle@xxxxxxxxxxxxx> >>>>> Signed-off-by: Sekhar Nori <nsekhar@xxxxxx> >>>>> --- >>>>> Jon, can you please confirm this fixes the issue you >>>>> reported? >>>> >>>> The patch does not apply on linux-3.12 due to changes to the 3 context >>>> lines at the start of the hunk. >>>> >>>> But, I manually fixed up the code and it does fix the issue on our AM1808 >>>> board. >>> >>> Thanks for the testing. The patch is meant for latest mainline but based >>> on what you said, a manual backport to v3.12-stable will be required. >>> >>> Can you please reply with a formal Tested-by: ? >> >> Tested-by: Jon Ringle <jringle@xxxxxxxxxxxxx> > where is this patch, somehow am not able to find in my inbox or archives... > I found it archived here: http://comments.gmane.org/gmane.linux.davinci/28569 Patch doesn't breaking anything for > MAX_NR_SG list size on AM335x, so it looks good. Acked-by: Joel Fernandes <joelf@xxxxxx> Regards, -Joel -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
