iio: adc: stm32-dfsdm: Use dma_request_chan() instead dma_request_slave_channel()

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: Olivier Moysan <olivier.moysan@st.com>
Acked-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/stm32-dfsdm-adc.c b/drivers/iio/adc/stm32-dfsdm-adc.c
index e493242..74a2211 100644 (file)
--- a/drivers/iio/adc/stm32-dfsdm-adc.c
+++ b/drivers/iio/adc/stm32-dfsdm-adc.c
@@ -1383,9 +1383,13 @@ static int stm32_dfsdm_dma_request(struct iio_dev *indio_dev)
 {
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
 
-       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,
@@ -1509,7 +1513,16 @@ static int stm32_dfsdm_adc_init(struct iio_dev *indio_dev)
        init_completion(&adc->completion);
 
        /* Optionally request DMA */
-       if (stm32_dfsdm_dma_request(indio_dev)) {
+       ret = stm32_dfsdm_dma_request(indio_dev);
+       if (ret) {
+               if (ret != -ENODEV) {
+                       if (ret != -EPROBE_DEFER)
+                               dev_err(&indio_dev->dev,
+                                       "DMA channel request failed with %d\n",
+                                       ret);
+                       return ret;
+               }
+
                dev_dbg(&indio_dev->dev, "No DMA support\n");
                return 0;
        }