Patch "dmaengine: pl330: Fix hang on dmaengine_terminate_all on certain boards" has been added to the 4.0-stable tree

This is a note to let you know that I've just added the patch titled

dmaengine: pl330: Fix hang on dmaengine_terminate_all on certain boards

to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
dmaengine-pl330-fix-hang-on-dmaengine_terminate_all-on-certain-boards.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Krzysztof Kozlowski <[email protected]>
Date: Thu, 21 May 2015 09:34:09 +0900
Subject: dmaengine: pl330: Fix hang on dmaengine_terminate_all on certain boards

From: Krzysztof Kozlowski <[email protected]>

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

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

@@ -2127,6 +2127,7 @@ static int pl330_terminate_all(struct dm
 	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 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;
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.0/dmaengine-fix-choppy-sound-because-of-unimplemented-resume.patch queue-4.0/dmaengine-pl330-fix-hang-on-dmaengine_terminate_all-on-certain-boards.patch queue-4.0/i2c-s3c2410-fix-oops-in-suspend-callback-for-non-dt.patch
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