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- From 60026ebc9abd3e719f56db57c482679176ae8881 Mon Sep 17 00:00:00 2001
- From: Matthias Reichl <hias@horus.com>
- Date: Tue, 7 Jun 2016 19:37:10 +0200
- 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>
- ---
- 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
- @@ -252,8 +252,11 @@ 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;
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