1 files changed, 19 insertions, 9 deletions

diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 9c41a4e42575..1072c450c37a 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -192,6 +192,7 @@ struct rcar_dmac_chan {
  * @iomem: remapped I/O memory base
  * @n_channels: number of available channels
  * @channels: array of DMAC channels
+ * @channels_mask: bitfield of which DMA channels are managed by this driver
  * @modules: bitmask of client modules in use
  */
 struct rcar_dmac {
@@ -202,6 +203,7 @@ struct rcar_dmac {
 
         unsigned int n_channels;
         struct rcar_dmac_chan *channels;
+        unsigned int channels_mask;
 
         DECLARE_BITMAP(modules, 256);
 };
@@ -438,7 +440,7 @@ static int rcar_dmac_init(struct rcar_dmac *dmac)
         u16 dmaor;
 
         /* Clear all channels and enable the DMAC globally. */
-        rcar_dmac_write(dmac, RCAR_DMACHCLR, GENMASK(dmac->n_channels - 1, 0));
+        rcar_dmac_write(dmac, RCAR_DMACHCLR, dmac->channels_mask);
         rcar_dmac_write(dmac, RCAR_DMAOR,
                         RCAR_DMAOR_PRI_FIXED | RCAR_DMAOR_DME);
 
@@ -814,6 +816,9 @@ static void rcar_dmac_stop_all_chan(struct rcar_dmac *dmac)
         for (i = 0; i < dmac->n_channels; ++i) {
                 struct rcar_dmac_chan *chan = &dmac->channels[i];
 
+                if (!(dmac->channels_mask & BIT(i)))
+                        continue;
+
                 /* Stop and reinitialize the channel. */
                 spin_lock_irq(&chan->lock);
                 rcar_dmac_chan_halt(chan);
@@ -1776,6 +1781,8 @@ static int rcar_dmac_chan_probe(struct rcar_dmac *dmac,
         return 0;
 }
 
+#define RCAR_DMAC_MAX_CHANNELS  32
+
 static int rcar_dmac_parse_of(struct device *dev, struct rcar_dmac *dmac)
 {
         struct device_node *np = dev->of_node;
@@ -1787,12 +1794,16 @@ static int rcar_dmac_parse_of(struct device *dev, struct rcar_dmac *dmac)
                 return ret;
         }
 
-        if (dmac->n_channels <= 0 || dmac->n_channels >= 100) {
+        /* The hardware and driver don't support more than 32 bits in CHCLR */
+        if (dmac->n_channels <= 0 ||
+            dmac->n_channels >= RCAR_DMAC_MAX_CHANNELS) {
                 dev_err(dev, "invalid number of channels %u\n",
                         dmac->n_channels);
                 return -EINVAL;
         }
 
+        dmac->channels_mask = GENMASK(dmac->n_channels - 1, 0);
+
         return 0;
 }
 
@@ -1802,7 +1813,6 @@ static int rcar_dmac_probe(struct platform_device *pdev)
                 DMA_SLAVE_BUSWIDTH_2_BYTES | DMA_SLAVE_BUSWIDTH_4_BYTES |
                 DMA_SLAVE_BUSWIDTH_8_BYTES | DMA_SLAVE_BUSWIDTH_16_BYTES |
                 DMA_SLAVE_BUSWIDTH_32_BYTES | DMA_SLAVE_BUSWIDTH_64_BYTES;
-        unsigned int channels_offset = 0;
         struct dma_device *engine;
         struct rcar_dmac *dmac;
         struct resource *mem;
@@ -1831,10 +1841,8 @@ static int rcar_dmac_probe(struct platform_device *pdev)
          * level we can't disable it selectively, so ignore channel 0 for now if
          * the device is part of an IOMMU group.
          */
-        if (device_iommu_mapped(&pdev->dev)) {
-                dmac->n_channels--;
-                channels_offset = 1;
-        }
+        if (device_iommu_mapped(&pdev->dev))
+                dmac->channels_mask &= ~BIT(0);
 
         dmac->channels = devm_kcalloc(&pdev->dev, dmac->n_channels,
                                       sizeof(*dmac->channels), GFP_KERNEL);
@@ -1892,8 +1900,10 @@ static int rcar_dmac_probe(struct platform_device *pdev)
         INIT_LIST_HEAD(&engine->channels);
 
         for (i = 0; i < dmac->n_channels; ++i) {
-                ret = rcar_dmac_chan_probe(dmac, &dmac->channels[i],
-                                           i + channels_offset);
+                if (!(dmac->channels_mask & BIT(i)))
+                        continue;
+
+                ret = rcar_dmac_chan_probe(dmac, &dmac->channels[i], i);
                 if (ret < 0)
                         goto error;
         }