spi: stm32: properly fail on dma_request_chan error

Correct handling of the dma_request_chan call in order to avoid
misleading warn message if no DMA is provided within the device-tree
and moreover fail if dma_request_chan has returned a valid error.

Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
Link: https://patch.msgid.link/20251218-stm32-spi-enhancements-v2-1-3b69901ca9fe@foss.st.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Alain Volmat

drivers/spi/spi-stm32.c

@@ -2406,23 +2406,27 @@ static int stm32_spi_probe(struct platform_device *pdev)
 	spi->dma_tx = dma_request_chan(spi->dev, "tx");
 	if (IS_ERR(spi->dma_tx)) {
 		ret = PTR_ERR(spi->dma_tx);
-		spi->dma_tx = NULL;
-		if (ret == -EPROBE_DEFER)
+		if (ret == -ENODEV) {
+			dev_info(&pdev->dev, "tx dma disabled\n");
+			spi->dma_tx = NULL;
+		} else {
+			dev_err_probe(&pdev->dev, ret, "failed to request tx dma channel\n");
 			goto err_clk_disable;
-
-		dev_warn(&pdev->dev, "failed to request tx dma channel\n");
+		}
 	} else {
 		ctrl->dma_tx = spi->dma_tx;
 	}
 
 	spi->dma_rx = dma_request_chan(spi->dev, "rx");
 	if (IS_ERR(spi->dma_rx)) {
 		ret = PTR_ERR(spi->dma_rx);
-		spi->dma_rx = NULL;
-		if (ret == -EPROBE_DEFER)
+		if (ret == -ENODEV) {
+			dev_info(&pdev->dev, "rx dma disabled\n");
+			spi->dma_rx = NULL;
+		} else {
+			dev_err_probe(&pdev->dev, ret, "failed to request rx dma channel\n");
 			goto err_dma_release;
-
-		dev_warn(&pdev->dev, "failed to request rx dma channel\n");
+		}
 	} else {
 		ctrl->dma_rx = spi->dma_rx;
 	}