Messages in this thread Patch in this message | | | From | Matthias Reichl <> | Subject | [PATCH 1/2] dmaengine: bcm2835: Fix cyclic DMA period splitting | Date | Thu, 9 Jun 2016 13:41:43 +0200 |
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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(-)
diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c index 6149b27..344bcf92 100644 --- a/drivers/dma/bcm2835-dma.c +++ b/drivers/dma/bcm2835-dma.c @@ -251,8 +251,11 @@ static void bcm2835_dma_create_cb_set_length( */ /* 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; -- 2.1.4
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