openwrtv4/target/linux/brcm2708/patches-4.9/950-0187-dmaengine-bcm2835-Fix-cyclic-DMA-period-splitting.patch
Rafał Miłecki fce21ae4cc brcm2708: rename all patches from raspberrypi git tree to use 950 prefix
Right now all brcm2708 patches are extracted from the non-mainline
raspberrypi/linux git tree. Many of them are hacks and/or are unneeded
in LEDE. Raspberry Pi is getting better and better mainline support so
it would be nice to finally start maintaining patches in a cleaner way:
1) Backport patches accepted in upstream tree
2) Start using upstream drivers
3) Pick only these patches that are needed for more complete support

Handling above tasks requires grouping patches - ideally using the same
prefixes as generic ones. It means we should rename existing patches to
use some high prefix. This will allow e.g. use 0xx for backported code.

Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Stijn Tintel <stijn@linux-ipv6.be>
2017-03-24 08:06:35 +01:00

39 lines
1.5 KiB
Diff

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;