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rcar-dmac: fixup descriptor pointer for descriptor mode

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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>
This commit is contained in:
Kuninori Morimoto 2017-05-23 07:08:43 +00:00 committed by Vinod Koul
parent 98f9de366f
commit 56b177055a
1 changed files with 3 additions and 0 deletions
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3
drivers/dma/sh/rcar-dmac.c
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@ -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;