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>

diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index db41795fe42ae6ed355de41f12b5c90ea661bde4..bd261c9e9664b6ac951939641091bc0bb7466380 100644 (file)
--- 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;