spi: imx: defer spi initialization, if DMA engine is

If SPI device supports DMA mode, but DMA controller is not yet
available due to e.g. a delay in the corresponding kernel module
initialization, retry to initialize SPI driver later on instead of
falling back into PIO only mode.

Signed-off-by: Anton Bondarenko <anton.bondarenko.sama@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-imx.c

@@ -1222,6 +1222,9 @@ static int spi_imx_probe(struct platform_device *pdev)
 	 */
 	if (is_imx51_ecspi(spi_imx)) {
 		ret = spi_imx_sdma_init(&pdev->dev, spi_imx, master, res);
+		if (ret == -EPROBE_DEFER)
+			goto out_clk_put;
+
 		if (ret < 0)
 			dev_err(&pdev->dev, "dma setup error %d, use pio\n",
 				ret);