From: Peter Ujfalusi <peter.ujfalusi@ti.com>
Date: Wed, 8 Jan 2020 08:08:01 +0000 (+0200)
Subject: iio: adc: stm32-adc: Use dma_request_chan() instead dma_request_slave_channel()
X-Git-Tag: Ubuntu-5.4.0-43.47~1744
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=106c2e4b392e6448acb87e1a364f701f5b9edb2d;p=mirror_ubuntu-focal-kernel.git

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

BugLink: https://bugs.launchpad.net/bugs/1881178

[ 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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
---

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,