mtd: fsmc_nand: add missing DMA unmap to dma_xfer()

Make dma_xfer() do DMA unmapping itself and fix handling
of failure cases.

Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Vipin Kumar <vipin.kumar@st.com>
Cc: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Dan Williams <djbw@fb.com>

drivers/mtd/nand/fsmc_nand.c

@@ -573,23 +573,22 @@ static int dma_xfer(struct fsmc_nand_data *host, void *buffer, int len,
 	dma_dev = chan->device;
 	dma_addr = dma_map_single(dma_dev->dev, buffer, len, direction);
 
+	flags |= DMA_COMPL_SKIP_SRC_UNMAP | DMA_COMPL_SKIP_DEST_UNMAP;
+
 	if (direction == DMA_TO_DEVICE) {
 		dma_src = dma_addr;
 		dma_dst = host->data_pa;
-		flags |= DMA_COMPL_SRC_UNMAP_SINGLE | DMA_COMPL_SKIP_DEST_UNMAP;
 	} else {
 		dma_src = host->data_pa;
 		dma_dst = dma_addr;
-		flags |= DMA_COMPL_DEST_UNMAP_SINGLE | DMA_COMPL_SKIP_SRC_UNMAP;
 	}
 
 	tx = dma_dev->device_prep_dma_memcpy(chan, dma_dst, dma_src,
 			len, flags);
-
 	if (!tx) {
 		dev_err(host->dev, "device_prep_dma_memcpy error\n");
-		dma_unmap_single(dma_dev->dev, dma_addr, len, direction);
-		return -EIO;
+		ret = -EIO;
+		goto unmap_dma;
 	}
 
 	tx->callback = dma_complete;
@@ -599,7 +598,7 @@ static int dma_xfer(struct fsmc_nand_data *host, void *buffer, int len,
 	ret = dma_submit_error(cookie);
 	if (ret) {
 		dev_err(host->dev, "dma_submit_error %d\n", cookie);
-		return ret;
+		goto unmap_dma;
 	}
 
 	dma_async_issue_pending(chan);
@@ -610,10 +609,17 @@ static int dma_xfer(struct fsmc_nand_data *host, void *buffer, int len,
 	if (ret <= 0) {
 		chan->device->device_control(chan, DMA_TERMINATE_ALL, 0);
 		dev_err(host->dev, "wait_for_completion_timeout\n");
-		return ret ? ret : -ETIMEDOUT;
+		if (!ret)
+			ret = -ETIMEDOUT;
+		goto unmap_dma;
 	}
 
-	return 0;
+	ret = 0;
+
+unmap_dma:
+	dma_unmap_single(dma_dev->dev, dma_addr, len, direction);
+
+	return ret;
 }
 
 /*