dmaengine: pl330: Fix hang on dmaengine_terminate_all on certain boards

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@opensource.altera.com>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Fixes: ae43b3289186 ("ARM: 8202/1: dmaengine: pl330: Add runtime Power Management support v12")
Cc: <stable@vger.kernel.org>
Tested-by: Dinh Nguyen <dinguyen@opensource.altera.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index a7d9d3029b145dfa29babeee33022bc1f7354d52..340f9e607cd8b90dfe75add027c18bd26d67f1e0 100644 (file)
--- 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;
 }