diff options
| author | Sekhar Nori <nsekhar@ti.com> | 2014-03-19 11:25:50 +0530 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2014-05-15 09:56:15 +0200 |
| commit | 4d22eb083cf667129e9158b407dda5588c89c64a (patch) | |
| tree | e3c5111a03dda5c5d677ee6551ca7ddfe9716a75 | |
| parent | 170012684d66273720f9a8a2f815e65d376da3e1 (diff) | |
dma: edma: fix incorrect SG list handling
commit 5fc68a6cad658e45dca3e0a6607df3a8e5df4ef9 upstream.
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: 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>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
| -rw-r--r-- | drivers/dma/edma.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c index 10b577fcf48d..0ad40e4a7ae0 100644 --- a/drivers/dma/edma.c +++ b/drivers/dma/edma.c @@ -170,11 +170,13 @@ static void edma_execute(struct edma_chan *echan) if (edesc->processed == edesc->pset_nr) edma_link(echan->slot[nslots-1], echan->ecc->dummy_slot); - edma_resume(echan->ch_num); - if (edesc->processed <= MAX_NR_SG) { dev_dbg(dev, "first transfer starting %d\n", echan->ch_num); edma_start(echan->ch_num); + } else { + dev_dbg(dev, "chan: %d: completed %d elements, resuming\n", + echan->ch_num, edesc->processed); + edma_resume(echan->ch_num); } /* |