Re: [PATCH 1/2] dmaengine: bcm2835: Fix cyclic DMA period splitting
Matthias Reichlwrites: > 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. It looks like this issue has been around for a long time, and this fix is pretty dependent on the recent refactors. Reviewed-by: Eric Anholt signature.asc Description: PGP signature
Re: [PATCH 1/2] dmaengine: bcm2835: Fix cyclic DMA period splitting
Matthias Reichl writes: > 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. It looks like this issue has been around for a long time, and this fix is pretty dependent on the recent refactors. Reviewed-by: Eric Anholt signature.asc Description: PGP signature
[PATCH 1/2] 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 ReichlSigned-off-by: Martin Sperl Tested-by: Clive Messer --- 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
[PATCH 1/2] 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 Signed-off-by: Martin Sperl Tested-by: Clive Messer --- 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