diff options
Diffstat (limited to 'drivers/dma/sh/rcar-dmac.c')
| -rw-r--r-- | drivers/dma/sh/rcar-dmac.c | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c index 2b4f25698169..e2a5398f89b5 100644 --- a/drivers/dma/sh/rcar-dmac.c +++ b/drivers/dma/sh/rcar-dmac.c @@ -1282,6 +1282,9 @@ static unsigned int rcar_dmac_chan_get_residue(struct rcar_dmac_chan *chan, enum dma_status status; unsigned int residue = 0; unsigned int dptr = 0; + unsigned int chcrb; + unsigned int tcrb; + unsigned int i; if (!desc) return 0; @@ -1330,14 +1333,31 @@ static unsigned int rcar_dmac_chan_get_residue(struct rcar_dmac_chan *chan, } /* + * We need to read two registers. + * Make sure the control register does not skip to next chunk + * while reading the counter. + * Trying it 3 times should be enough: Initial read, retry, retry + * for the paranoid. + */ + for (i = 0; i < 3; i++) { + chcrb = rcar_dmac_chan_read(chan, RCAR_DMACHCRB) & + RCAR_DMACHCRB_DPTR_MASK; + tcrb = rcar_dmac_chan_read(chan, RCAR_DMATCRB); + /* Still the same? */ + if (chcrb == (rcar_dmac_chan_read(chan, RCAR_DMACHCRB) & + RCAR_DMACHCRB_DPTR_MASK)) + break; + } + WARN_ONCE(i >= 3, "residue might be not continuous!"); + + /* * In descriptor mode the descriptor running pointer is not maintained * by the interrupt handler, find the running descriptor from the * descriptor pointer field in the CHCRB register. In non-descriptor * mode just use the running descriptor pointer. */ if (desc->hwdescs.use) { - dptr = (rcar_dmac_chan_read(chan, RCAR_DMACHCRB) & - RCAR_DMACHCRB_DPTR_MASK) >> RCAR_DMACHCRB_DPTR_SHIFT; + dptr = chcrb >> RCAR_DMACHCRB_DPTR_SHIFT; if (dptr == 0) dptr = desc->nchunks; dptr--; @@ -1355,7 +1375,7 @@ static unsigned int rcar_dmac_chan_get_residue(struct rcar_dmac_chan *chan, } /* Add the residue for the current chunk. */ - residue += rcar_dmac_chan_read(chan, RCAR_DMATCRB) << desc->xfer_shift; + residue += tcrb << desc->xfer_shift; return residue; } @@ -1368,6 +1388,7 @@ static enum dma_status rcar_dmac_tx_status(struct dma_chan *chan, enum dma_status status; unsigned long flags; unsigned int residue; + bool cyclic; status = dma_cookie_status(chan, cookie, txstate); if (status == DMA_COMPLETE || !txstate) @@ -1375,10 +1396,11 @@ static enum dma_status rcar_dmac_tx_status(struct dma_chan *chan, spin_lock_irqsave(&rchan->lock, flags); residue = rcar_dmac_chan_get_residue(rchan, cookie); + cyclic = rchan->desc.running ? rchan->desc.running->cyclic : false; spin_unlock_irqrestore(&rchan->lock, flags); /* if there's no residue, the cookie is complete */ - if (!residue) + if (!residue && !cyclic) return DMA_COMPLETE; dma_set_residue(txstate, residue); |