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Diffstat (limited to 'target/linux/brcm2708/patches-4.9/0187-dmaengine-bcm2835-Fix-cyclic-DMA-period-splitting.patch')
-rw-r--r--target/linux/brcm2708/patches-4.9/0187-dmaengine-bcm2835-Fix-cyclic-DMA-period-splitting.patch39
1 files changed, 39 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.9/0187-dmaengine-bcm2835-Fix-cyclic-DMA-period-splitting.patch b/target/linux/brcm2708/patches-4.9/0187-dmaengine-bcm2835-Fix-cyclic-DMA-period-splitting.patch
new file mode 100644
index 0000000000..fa0d998a2d
--- /dev/null
+++ b/target/linux/brcm2708/patches-4.9/0187-dmaengine-bcm2835-Fix-cyclic-DMA-period-splitting.patch
@@ -0,0 +1,39 @@
+From 9fd7a158ec098ab05b8d3ec2c2973b3dc7e498f3 Mon Sep 17 00:00:00 2001
+From: Matthias Reichl <hias@horus.com>
+Date: Mon, 20 Feb 2017 20:01:16 +0100
+Subject: [PATCH] dmaengine: bcm2835: Fix cyclic DMA period splitting
+
+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.
+
+Signed-off-by: Matthias Reichl <hias@horus.com>
+Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
+Tested-by: Clive Messer <clive.messer@digitaldreamtime.co.uk>
+Reviewed-by: Eric Anholt <eric@anholt.net>
+---
+ drivers/dma/bcm2835-dma.c | 5 ++++-
+ 1 file changed, 4 insertions(+), 1 deletion(-)
+
+--- a/drivers/dma/bcm2835-dma.c
++++ b/drivers/dma/bcm2835-dma.c
+@@ -253,8 +253,11 @@ 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;