mtd: nand: sh_flctl: handle dma_submit() errors

Some build tools noticed that 'cookie' is being set but not used. Might
as well catch the errors here and handle them the same way we handle
other DMA prep steps.
Signed-off-by: NBrian Norris <computersforpeace@gmail.com>
Signed-off-by: NBoris Brezillon <boris.brezillon@free-electrons.com>

drivers/mtd/nand/sh_flctl.c

@@ -397,7 +397,7 @@ static int flctl_dma_fifo0_transfer(struct sh_flctl *flctl, unsigned long *buf,
 	struct dma_chan *chan;
 	enum dma_transfer_direction tr_dir;
 	dma_addr_t dma_addr;
-	dma_cookie_t cookie = -EINVAL;
+	dma_cookie_t cookie;
 	uint32_t reg;
 	int ret;
 
@@ -423,6 +423,12 @@ static int flctl_dma_fifo0_transfer(struct sh_flctl *flctl, unsigned long *buf,
 		desc->callback = flctl_dma_complete;
 		desc->callback_param = flctl;
 		cookie = dmaengine_submit(desc);
+		if (dma_submit_error(cookie)) {
+			ret = dma_submit_error(cookie);
+			dev_warn(&flctl->pdev->dev,
+				 "DMA submit failed, falling back to PIO\n");
+			goto out;
+		}
 
 		dma_async_issue_pending(chan);
 	} else {