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Subject[PATCH 5.4 102/111] iio: adc: stm32-adc: Use dma_request_chan() instead dma_request_slave_channel()
Date
From: Peter Ujfalusi <peter.ujfalusi@ti.com>

[ Upstream commit 735404b846dffcb320264f62b76e6f70012214dd ]

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@ti.com>
Acked-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/iio/adc/stm32-adc.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 9f63ceb15865..a2279cccb584 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -1763,9 +1763,21 @@ 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)) {
+ ret = PTR_ERR(adc->dma_chan);
+ if (ret != -ENODEV) {
+ if (ret != -EPROBE_DEFER)
+ dev_err(&indio_dev->dev,
+ "DMA channel request failed with %d\n",
+ ret);
+ return ret;
+ }
+
+ /* DMA is optional: 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,
--
2.25.1


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