* [PATCH] rcar-dmac: fixup descriptor pointer for descriptor mode
@ 2017-05-23 7:08 Kuninori Morimoto
2017-05-30 6:20 ` Vinod Koul
0 siblings, 1 reply; 2+ messages in thread
From: Kuninori Morimoto @ 2017-05-23 7:08 UTC (permalink / raw)
To: Dan Williams, Vinod Koul, Laurent Pinchart, Geert Uytterhoeven
Cc: dmaengine, linux-kernel
From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
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@renesas.com>
---
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
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] rcar-dmac: fixup descriptor pointer for descriptor mode
2017-05-23 7:08 [PATCH] rcar-dmac: fixup descriptor pointer for descriptor mode Kuninori Morimoto
@ 2017-05-30 6:20 ` Vinod Koul
0 siblings, 0 replies; 2+ messages in thread
From: Vinod Koul @ 2017-05-30 6:20 UTC (permalink / raw)
To: Kuninori Morimoto
Cc: Dan Williams, Laurent Pinchart, Geert Uytterhoeven, dmaengine,
linux-kernel
On Tue, May 23, 2017 at 07:08:43AM +0000, Kuninori Morimoto wrote:
>
> From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
>
> 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.
Applied, thanks
--
~Vinod
^ permalink raw reply [flat|nested] 2+ messages in thread
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