mtd: rawnand: Fix return value check of wait_for_completion_timeout

wait_for_completion_timeout() returns unsigned long not int.
It returns 0 if timed out, and positive if completed.
The check for <= 0 is ambiguous and should be == 0 here
indicating timeout which is the only error case.

Fixes: 83738d8 ("mtd: sh_flctl: Add DMA capabilty")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20220412083435.29254-1-linmq006@gmail.com

Author: Yuuoniy

drivers/mtd/nand/raw/sh_flctl.c

@@ -384,7 +384,8 @@ static int flctl_dma_fifo0_transfer(struct sh_flctl *flctl, unsigned long *buf,
 	dma_addr_t dma_addr;
 	dma_cookie_t cookie;
 	uint32_t reg;
-	int ret;
+	int ret = 0;
+	unsigned long time_left;
 
 	if (dir == DMA_FROM_DEVICE) {
 		chan = flctl->chan_fifo0_rx;
@@ -425,13 +426,14 @@ static int flctl_dma_fifo0_transfer(struct sh_flctl *flctl, unsigned long *buf,
 		goto out;
 	}
 
-	ret =
+	time_left =
 	wait_for_completion_timeout(&flctl->dma_complete,
 				msecs_to_jiffies(3000));
 
-	if (ret <= 0) {
+	if (time_left == 0) {
 		dmaengine_terminate_all(chan);
 		dev_err(&flctl->pdev->dev, "wait_for_completion_timeout\n");
+		ret = -ETIMEDOUT;
 	}
 
 out:
@@ -441,7 +443,7 @@ static int flctl_dma_fifo0_transfer(struct sh_flctl *flctl, unsigned long *buf,
 
 	dma_unmap_single(chan->device->dev, dma_addr, len, dir);
 
-	/* ret > 0 is success */
+	/* ret == 0 is success */
 	return ret;
 }
 
@@ -465,7 +467,7 @@ static void read_fiforeg(struct sh_flctl *flctl, int rlen, int offset)
 
 	/* initiate DMA transfer */
 	if (flctl->chan_fifo0_rx && rlen >= 32 &&
-		flctl_dma_fifo0_transfer(flctl, buf, rlen, DMA_FROM_DEVICE) > 0)
+		!flctl_dma_fifo0_transfer(flctl, buf, rlen, DMA_FROM_DEVICE))
 			goto convert;	/* DMA success */
 
 	/* do polling transfer */
@@ -524,7 +526,7 @@ static void write_ec_fiforeg(struct sh_flctl *flctl, int rlen,
 
 	/* initiate DMA transfer */
 	if (flctl->chan_fifo0_tx && rlen >= 32 &&
-		flctl_dma_fifo0_transfer(flctl, buf, rlen, DMA_TO_DEVICE) > 0)
+		!flctl_dma_fifo0_transfer(flctl, buf, rlen, DMA_TO_DEVICE))
 			return;	/* DMA success */
 
 	/* do polling transfer */