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: ? Regards, Sekhar -- 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
