mtd: rawnand: stm32_fmc2: Use dma_request_chan() instead dma_request_slave_channel()

dma_request_slave_channel() is a wrapper on top of dma_request_chan()
eating up the error code.

Use using dma_request_chan() directly and inform user of error in case the
DMA request failed.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200227123749.24064-8-peter.ujfalusi@ti.com

drivers/mtd/nand/raw/stm32_fmc2_nand.c

@@ -1606,15 +1606,36 @@ static int stm32_fmc2_setup_interface(struct nand_chip *chip, int chipnr,
 /* DMA configuration */
 static int stm32_fmc2_dma_setup(struct stm32_fmc2_nfc *fmc2)
 {
-	int ret;
+	int ret = 0;
 
-	fmc2->dma_tx_ch = dma_request_slave_channel(fmc2->dev, "tx");
-	fmc2->dma_rx_ch = dma_request_slave_channel(fmc2->dev, "rx");
-	fmc2->dma_ecc_ch = dma_request_slave_channel(fmc2->dev, "ecc");
+	fmc2->dma_tx_ch = dma_request_chan(fmc2->dev, "tx");
+	if (IS_ERR(fmc2->dma_tx_ch)) {
+		ret = PTR_ERR(fmc2->dma_tx_ch);
+		if (ret != -ENODEV)
+			dev_err(fmc2->dev,
+				"failed to request tx DMA channel: %d\n", ret);
+		fmc2->dma_tx_ch = NULL;
+		goto err_dma;
+	}
 
-	if (!fmc2->dma_tx_ch || !fmc2->dma_rx_ch || !fmc2->dma_ecc_ch) {
-		dev_warn(fmc2->dev, "DMAs not defined in the device tree, polling mode is used\n");
-		return 0;
+	fmc2->dma_rx_ch = dma_request_chan(fmc2->dev, "rx");
+	if (IS_ERR(fmc2->dma_rx_ch)) {
+		ret = PTR_ERR(fmc2->dma_rx_ch);
+		if (ret != -ENODEV)
+			dev_err(fmc2->dev,
+				"failed to request rx DMA channel: %d\n", ret);
+		fmc2->dma_rx_ch = NULL;
+		goto err_dma;
+	}
+
+	fmc2->dma_ecc_ch = dma_request_chan(fmc2->dev, "ecc");
+	if (IS_ERR(fmc2->dma_ecc_ch)) {
+		ret = PTR_ERR(fmc2->dma_ecc_ch);
+		if (ret != -ENODEV)
+			dev_err(fmc2->dev,
+				"failed to request ecc DMA channel: %d\n", ret);
+		fmc2->dma_ecc_ch = NULL;
+		goto err_dma;
 	}
 
 	ret = sg_alloc_table(&fmc2->dma_ecc_sg, FMC2_MAX_SG, GFP_KERNEL);
@@ -1635,6 +1656,15 @@ static int stm32_fmc2_dma_setup(struct stm32_fmc2_nfc *fmc2)
 	init_completion(&fmc2->dma_ecc_complete);
 
 	return 0;
+
+err_dma:
+	if (ret == -ENODEV) {
+		dev_warn(fmc2->dev,
+			 "DMAs not defined in the DT, polling mode is used\n");
+		ret = 0;
+	}
+
+	return ret;
 }
 
 /* NAND callbacks setup */