[v3,1/2] dmaengine: sh: rcar-dmac: With cyclic DMA residue 0 is valid

[Dirk Behme <dirk.behme@de.bosch.com>]

Having a cyclic DMA, a residue 0 is not an indication of a completed
DMA. In case of cyclic DMA make sure that dma_set_residue() is called
and with this a residue of 0 is forwarded correctly to the caller.

Fixes: 3544d2878817 ("dmaengine: rcar-dmac: use result of updated get_residue in tx_status")
Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Signed-off-by: Achim Dahlhoff <Achim.Dahlhoff@de.bosch.com>
Signed-off-by: Hiroyuki Yokoyama <hiroyuki.yokoyama.vx@renesas.com>
Signed-off-by: Yao Lihua <ylhuajnu@outlook.com>
Cc: <stable@vger.kernel.org> # v4.8+
---
Note: Patch done against mainline v5.0

Changes in v2: None

Changes in v3: Move reading rchan into the spin lock protection.

 drivers/dma/sh/rcar-dmac.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 2b4f25698169..54810ffd95e2 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -1368,6 +1368,7 @@ static enum dma_status rcar_dmac_tx_status(struct dma_chan *chan,
 	enum dma_status status;
 	unsigned long flags;
 	unsigned int residue;
+	bool cyclic;
 
 	status = dma_cookie_status(chan, cookie, txstate);
 	if (status == DMA_COMPLETE || !txstate)
@@ -1375,10 +1376,11 @@ static enum dma_status rcar_dmac_tx_status(struct dma_chan *chan,
 
 	spin_lock_irqsave(&rchan->lock, flags);
 	residue = rcar_dmac_chan_get_residue(rchan, cookie);
+	cyclic = rchan->desc.running ? rchan->desc.running->cyclic : false;
 	spin_unlock_irqrestore(&rchan->lock, flags);
 
 	/* if there's no residue, the cookie is complete */
-	if (!residue)
+	if (!residue && !cyclic)
 		return DMA_COMPLETE;
 
 	dma_set_residue(txstate, residue);