dmaengine: rcar-dmac: unmap slave resource when channel is freed

The slave mapping should be removed together with other channel
resources when the channel is freed. If it's not unmapped it will hang
around forever after the channel is freed.

Fixes: 9f878603db ("dmaengine: rcar-dmac: add iommu support for slave transfers")
Reported-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

drivers/dma/sh/rcar-dmac.c

@@ -986,6 +986,7 @@ static void rcar_dmac_free_chan_resources(struct dma_chan *chan)
 {
 	struct rcar_dmac_chan *rchan = to_rcar_dmac_chan(chan);
 	struct rcar_dmac *dmac = to_rcar_dmac(chan->device);
+	struct rcar_dmac_chan_map *map = &rchan->map;
 	struct rcar_dmac_desc_page *page, *_page;
 	struct rcar_dmac_desc *desc;
 	LIST_HEAD(list);
@@ -1019,6 +1020,13 @@ static void rcar_dmac_free_chan_resources(struct dma_chan *chan)
 		free_page((unsigned long)page);
 	}
 
+	/* Remove slave mapping if present. */
+	if (map->slave.xfer_size) {
+		dma_unmap_resource(chan->device->dev, map->addr,
+				   map->slave.xfer_size, map->dir, 0);
+		map->slave.xfer_size = 0;
+	}
+
 	pm_runtime_put(chan->device->dev);
 }