[v3] dmaengine: rcar-dmac: clear channel register when error

[Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>]

From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>

We need to clear channel register in error case as recovery.
The channel is already stopped in such case, thus we don't need to call
rcar_dmac_chan_halt() before clearing.

rcar_dmac_chan_halt() will clear and confirm DE bit.
But it will be failed because channel is already stopped in error case.
In other words, we shouldn't call it then.

Reported-by: Hiroki Negishi <hiroki.negishi.bx@renesas.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Hiroki Negishi <hiroki.negishi.bx@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
---
v2 -> v3

 - use to_rcar_dmac()
 - add Simon's Reviewed-by

 drivers/dma/sh/rcar-dmac.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 279c930..79d14af 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -1525,7 +1525,15 @@ static irqreturn_t rcar_dmac_isr_channel(int irq, void *dev)
 
 	chcr = rcar_dmac_chan_read(chan, RCAR_DMACHCR);
 	if (chcr & RCAR_DMACHCR_CAE) {
-		rcar_dmac_chan_halt(chan);
+		struct rcar_dmac *dmac = to_rcar_dmac(chan->chan.device);
+
+		/*
+		 * We don't need to call rcar_dmac_chan_halt()
+		 * because channel is already stopped in error case.
+		 * We need to clear register and check DE bit as recovery.
+		 */
+		rcar_dmac_write(dmac, RCAR_DMACHCLR, 1 << chan->index);
+		rcar_dmac_chcr_de_barrier(chan);
 		reinit = true;
 		goto spin_lock_end;
 	}