[PATCH 4/4] dmaengine: omap-dma: Handle cases when the channel is polled for completion

From: Peter Ujfalusi
Date: Wed Nov 11 2015 - 05:38:35 EST

When a DMA client driver decides that it is not providing callback for
completion of a transfer (and/or does not set the DMA_PREP_INTERRUPT) but
it will poll the status of the transfer (in case of short memcpy for
example) we will not get interrupt for the completion of the transfer and
will not mark the transaction as done.
Check the channel enable bit in the CCR when the status is queried and if
the channel is no longer active, we call the omap_dma_callback() to handle
the transfer completion.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
drivers/dma/omap-dma.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/drivers/dma/omap-dma.c b/drivers/dma/omap-dma.c
index 4e4642f561f5..f86827ac0c8a 100644
--- a/drivers/dma/omap-dma.c
+++ b/drivers/dma/omap-dma.c
@@ -673,8 +673,14 @@ static enum dma_status omap_dma_tx_status(struct dma_chan *chan,
struct omap_chan *c = to_omap_dma_chan(chan);
struct virt_dma_desc *vd;
enum dma_status ret;
+ uint32_t ccr;
unsigned long flags;

+ ccr = omap_dma_chan_read(c, CCR);
+ /* The channel is no longer active, handle the completion right away */
+ if (!(ccr & CCR_ENABLE))
+ omap_dma_callback(c->dma_ch, 0, c);
ret = dma_cookie_status(chan, cookie, txstate);
if (ret == DMA_COMPLETE || !txstate)
return ret;

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