[PATCH 3/3] dma: mxs-dma: Pause channel while prep_dma_cyclic
From: Markus Pargmann <hidden>
Date: 2013-09-26 15:06:36
Subsystem:
dma generic offload engine subsystem, the rest · Maintainers:
Vinod Koul, Linus Torvalds
Using mxs-dma with pcm-dmaengine with small period-length can in some cases lead to strange audio effects. This patch pauses the DMA channel while preparing cyclic DMA commands. I tested with mx28 and period-length of 160. Signed-off-by: Markus Pargmann <redacted> --- drivers/dma/mxs-dma.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/dma/mxs-dma.c b/drivers/dma/mxs-dma.c
index 13c7d83..bdde315 100644
--- a/drivers/dma/mxs-dma.c
+++ b/drivers/dma/mxs-dma.c@@ -568,8 +568,8 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_dma_cyclic( if (mxs_chan->status == DMA_IN_PROGRESS) return NULL; - mxs_chan->status = DMA_IN_PROGRESS; - mxs_chan->flags |= MXS_DMA_SG_LOOP; + mxs_dma_pause_chan(mxs_chan); + mxs_dma_reset_chan(mxs_chan); if (num_periods > NUM_CCW) { dev_err(mxs_dma->dma_device.dev,
@@ -609,6 +609,11 @@ static struct dma_async_tx_descriptor *mxs_dma_prep_dma_cyclic( i++; } + mxs_dma_resume_chan(mxs_chan); + + mxs_chan->status = DMA_IN_PROGRESS; + mxs_chan->flags |= MXS_DMA_SG_LOOP; + mxs_chan->desc_count = i; return &mxs_chan->desc;
--
1.8.4.rc3