Patch "dmaengine: bcm2835: Fix cyclic DMA period splitting" has been added to the 4.9-stable tree

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

dmaengine: bcm2835: Fix cyclic DMA period splitting

to the 4.9-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-bcm2835-fix-cyclic-dma-period-splitting.patch
and it can be found in the queue-4.9 subdirectory.

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

From: Matthias Reichl <[email protected]>
Date: Mon, 20 Feb 2017 20:01:16 +0100
Subject: dmaengine: bcm2835: Fix cyclic DMA period splitting

From: Matthias Reichl <[email protected]>

commit 2201ac6129fa162ac24da089a034bb0971648ebb upstream.

The code responsible for splitting periods into chunks that can be handled by the DMA controller missed to update total_len, the number of bytes processed in the current period, when there are more chunks to follow.

Therefore total_len was stuck at 0 and the code didn't work at all. This resulted in a wrong control block layout and audio issues because the cyclic DMA callback wasn't executing on period boundaries.

Fix this by adding the missing total_len update.

---
 drivers/dma/bcm2835-dma.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

@@ -251,8 +251,11 @@ static void bcm2835_dma_create_cb_set_le
 	 */
 
 	/* have we filled in period_length yet? */
-	if (*total_len + control_block->length < period_len)
+	if (*total_len + control_block->length < period_len) {
+		/* update number of bytes in this period so far */
+		*total_len += control_block->length;
 		return;
+	}
 
 	/* calculate the length that remains to reach period_length */
 	control_block->length = period_len - *total_len;

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

queue-4.9/dmaengine-bcm2835-fix-cyclic-dma-period-splitting.patch