[PATCH 4.19 77/81] iio: adc: stm32-dfsdm: Use dma_request_chan() instead dma_request_slave_channel()

[Greg Kroah-Hartman]

From: Peter Ujfalusi <peter.ujfalusi@xxxxxx>

[ Upstream commit a9ab624edd9186fbad734cfe5d606a6da3ca34db ]

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>
Acked-by: Olivier Moysan <olivier.moysan@xxxxxx>
Acked-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/iio/adc/stm32-dfsdm-adc.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c
index f5586dd6414d..516d7d22d9f4 100644
--- a/drivers/iio/adc/stm32-dfsdm-adc.c
+++ b/drivers/iio/adc/stm32-dfsdm-adc.c
@@ -933,9 +933,13 @@ static int stm32_dfsdm_dma_request(struct iio_dev *indio_dev)
 	};
 	int ret;
 
-	adc->dma_chan = dma_request_slave_channel(&indio_dev->dev, "rx");
-	if (!adc->dma_chan)
-		return -EINVAL;
+	adc->dma_chan = dma_request_chan(&indio_dev->dev, "rx");
+	if (IS_ERR(adc->dma_chan)) {
+		int ret = PTR_ERR(adc->dma_chan);
+
+		adc->dma_chan = NULL;
+		return ret;
+	}
 
 	adc->rx_buf = dma_alloc_coherent(adc->dma_chan->device->dev,
 					 DFSDM_DMA_BUFFER_SIZE,
-- 
2.25.1