Merge tag 'dmaengine-5.2-rc1' of git://git.infradead.org/users/vkoul/slave-dma

[linux-2.6-block.git] / drivers / dma / sh / rcar-dmac.c

diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 580ca1454fe8cf2778f6391c7dfcd3837770165b..33ab1b607e2b0f5cc136bad35f17c006d3e6ac2b 100644 (file)
--- 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;
@@ -1329,6 +1332,24 @@ static unsigned int rcar_dmac_chan_get_residue(struct rcar_dmac_chan *chan,
                return 0;
        }
 
+       /*
+        * 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
@@ -1336,8 +1357,7 @@ static unsigned int rcar_dmac_chan_get_residue(struct rcar_dmac_chan *chan,
         * 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);