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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>
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;