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")
Cc: <stable@xxxxxxxxxxxxxxx>
Cc: Dinh Nguyen <dinguyen@xxxxxxxxxxxxxxxxxxxxx>
---
drivers/dma/pl330.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index a7d9d3029b14..340f9e607cd8 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -2127,6 +2127,7 @@ static int pl330_terminate_all(struct dma_chan *chan)
struct pl330_dmac *pl330 = pch->dmac;
LIST_HEAD(list);
+ pm_runtime_get_sync(pl330->ddma.dev);
spin_lock_irqsave(&pch->lock, flags);
spin_lock(&pl330->lock);
_stop(pch->thread);
@@ -2151,6 +2152,8 @@ static int pl330_terminate_all(struct dma_chan *chan)
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;
}
--
1.9.1
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