From: Sekhar Nori Date: Wed, 19 Mar 2014 05:55:50 +0000 (+0530) Subject: dma: edma: fix incorrect SG list handling X-Git-Tag: omap-for-v3.16/pm-signed~68^2~3 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=5fc68a6cad658e45dca3e0a6607df3a8e5df4ef9;p=pandora-kernel.git dma: edma: fix incorrect SG list handling 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 Acked-by: Joel Fernandes Tested-by: Jon Ringle Tested-by: Alexander Holler Reported-by: Jon Ringle Signed-off-by: Sekhar Nori Signed-off-by: Vinod Koul --- Reading git-diff-tree failed