From: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
In descriptor mode, the descriptor running pointer is not maintained
by the interrupt handler, thus, driver finds the running descriptor
from the descriptor pointer field in the CHCRB register.
But, CHCRB::DPTR indicates *next* descriptor pointer, not current.
Thus, The residue calculation will be missed. This patch fixup it.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@xxxxxxxxxxx>
---
drivers/dma/sh/rcar-dmac.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index d2cb4a0..ffcadca 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -1293,6 +1293,9 @@ static unsigned int rcar_dmac_chan_get_residue(struct rcar_dmac_chan *chan,
if (desc->hwdescs.use) {
dptr = (rcar_dmac_chan_read(chan, RCAR_DMACHCRB) &
RCAR_DMACHCRB_DPTR_MASK) >> RCAR_DMACHCRB_DPTR_SHIFT;
+ if (dptr == 0)
+ dptr = desc->nchunks;
+ dptr--;
WARN_ON(dptr >= desc->nchunks);
} else {
running = desc->running;
--
1.9.1
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