2016-09-10 12:54:26 +00:00
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From aaf4cb4fda9ed5c19f0db02023c5c11f51a23aaf Mon Sep 17 00:00:00 2001
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2016-07-07 07:22:07 +00:00
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From: Matthias Reichl <hias@horus.com>
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Date: Tue, 7 Jun 2016 19:37:10 +0200
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2016-09-10 12:54:26 +00:00
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Subject: [PATCH] dmaengine: bcm2835: Fix cyclic DMA period splitting
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2016-07-07 07:22:07 +00:00
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The code responsible for splitting periods into chunks that
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can be handled by the DMA controller missed to update total_len,
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the number of bytes processed in the current period, when there
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are more chunks to follow.
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Therefore total_len was stuck at 0 and the code didn't work at all.
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This resulted in a wrong control block layout and audio issues because
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the cyclic DMA callback wasn't executing on period boundaries.
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Fix this by adding the missing total_len update.
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Signed-off-by: Matthias Reichl <hias@horus.com>
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Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
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Tested-by: Clive Messer <clive.messer@digitaldreamtime.co.uk>
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---
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drivers/dma/bcm2835-dma.c | 5 ++++-
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1 file changed, 4 insertions(+), 1 deletion(-)
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--- a/drivers/dma/bcm2835-dma.c
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+++ b/drivers/dma/bcm2835-dma.c
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@@ -252,8 +252,11 @@ static void bcm2835_dma_create_cb_set_le
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*/
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/* have we filled in period_length yet? */
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- if (*total_len + control_block->length < period_len)
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+ if (*total_len + control_block->length < period_len) {
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+ /* update number of bytes in this period so far */
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+ *total_len += control_block->length;
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return;
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+ }
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/* calculate the length that remains to reach period_length */
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control_block->length = period_len - *total_len;
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