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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>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Matthias Reichl 2017-02-20 20:01:16 +01:00 committed by Vinod Koul
parent c1ae3cfa0e
commit 2201ac6129
1 changed files with 4 additions and 1 deletions
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5
drivers/dma/bcm2835-dma.c
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@ -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;