[PATCH] iio: adc: stm32-adc: Use dma_request_chan() instead dma_request_slave_channel()

[Peter Ujfalusi]

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

By using dma_request_chan() directly the driver can support deferred
probing against DMA.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
---
 drivers/iio/adc/stm32-adc.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 3b291d72701c..5dab23f1fdee 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -1746,9 +1746,15 @@ static int stm32_adc_dma_request(struct iio_dev *indio_dev)
 	struct dma_slave_config config;
 	int ret;
 
-	adc->dma_chan = dma_request_slave_channel(&indio_dev->dev, "rx");
-	if (!adc->dma_chan)
+	adc->dma_chan = dma_request_chan(&indio_dev->dev, "rx");
+	if (IS_ERR(adc->dma_chan)) {
+		if (PTR_ERR(adc->dma_chan) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+
+		/* Ignore errors to fall back to IRQ mode */
+		adc->dma_chan = NULL;
 		return 0;
+	}
 
 	adc->rx_buf = dma_alloc_coherent(adc->dma_chan->device->dev,
 					 STM32_DMA_BUFFER_SIZE,
-- 
Peter

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