From 56b177055adb246cdeca174331dbf92fc49bfccd Mon Sep 17 00:00:00 2001
From: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Date: Tue, 23 May 2017 07:08:43 +0000
Subject: [PATCH] rcar-dmac: fixup descriptor pointer for descriptor mode
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>
Signed-off-by: Vinod Koul <vinod.koul@intel.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 db41795fe42a..bd261c9e9664 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -1287,6 +1287,9 @@ 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;
--
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