[PATCH 4.0 046/105] dmaengine: pl330: Fix hang on dmaengine_terminate_all on certain boards

From: Greg Kroah-Hartman
Date: Fri Jun 19 2015 - 17:17:19 EST

4.0-stable review patch. If anyone has any objections, please let me know.


From: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>

commit 81cc6edc08705ac0146fe6ac14a0982a31ce6f3d upstream.

The pl330 device could hang infinitely on certain boards when DMA
channels are terminated.

It was caused by lack of runtime resume when executing
pl330_terminate_all() which calls the _stop() function. _stop() accesses
device register and can loop infinitely while checking for device state.

The hang was confirmed by Dinh Nguyen on Altera SOCFPGA Cyclone V
board during boot. It can be also triggered with:

$ echo 1 > /sys/module/dmatest/parameters/iterations
$ echo dma1chan0 > /sys/module/dmatest/parameters/channel
$ echo 1 > /sys/module/dmatest/parameters/run
$ sleep 1
$ cat /sys/module/dmatest/parameters/run

Reported-by: Dinh Nguyen <dinguyen@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx>
Fixes: ae43b3289186 ("ARM: 8202/1: dmaengine: pl330: Add runtime Power Management support v12")
Tested-by: Dinh Nguyen <dinguyen@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Vinod Koul <vinod.koul@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/dma/pl330.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -2127,6 +2127,7 @@ static int pl330_terminate_all(struct dm
struct pl330_dmac *pl330 = pch->dmac;

+ pm_runtime_get_sync(pl330->ddma.dev);
spin_lock_irqsave(&pch->lock, flags);
@@ -2151,6 +2152,8 @@ static int pl330_terminate_all(struct dm
list_splice_tail_init(&pch->work_list, &pl330->desc_pool);
list_splice_tail_init(&pch->completed_list, &pl330->desc_pool);
spin_unlock_irqrestore(&pch->lock, flags);
+ pm_runtime_mark_last_busy(pl330->ddma.dev);
+ pm_runtime_put_autosuspend(pl330->ddma.dev);

return 0;

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