diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.9/950-0187-dmaengine-bcm2835-Fix-cyclic-DMA-period-splitting.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.9/950-0187-dmaengine-bcm2835-Fix-cyclic-DMA-period-splitting.patch | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.9/950-0187-dmaengine-bcm2835-Fix-cyclic-DMA-period-splitting.patch b/target/linux/brcm2708/patches-4.9/950-0187-dmaengine-bcm2835-Fix-cyclic-DMA-period-splitting.patch new file mode 100644 index 0000000..fa0d998 --- /dev/null +++ b/target/linux/brcm2708/patches-4.9/950-0187-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; |