[PATCH v2 1/1] spi: spi-imx: Use dev_err_probe for failed DMA channel requests

[Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>]

If dma_request_chan() fails, no error is shown nor any information is
shown in /sys/kernel/debug/devices_deferred if -EPROBE_DEFER is returned.
Use dev_err_probe to fix both problems.

Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
---
Sorry, I lost sight of the replies from v1 series. I'll address Fabio's
concern here instead.

It's true that running spi-imx with SDMA is valid. But if provided DMA
channels are not available, aka -EPROBE_DEFER, there is no information
why so. This can simply be seen by disabling the sdma1 node on imx8mp:
$ cat /sys/kernel/debug/devices_deferred 
30820000.spi
30830000.spi
30840000.spi

There is no indication what is wrong/missing here. There is also no fallback
to pio mode.
This patch addresses this by setting the defer probe reason.

Changes in v2:
* Rebase to next-20240110

[1] https://lore.kernel.org/all/CAOMZO5CcD5iDkaempdxnQHx1fAgnXAmMq_0MdEq5wNgOLHcMuw@xxxxxxxxxxxxxx/

 drivers/spi/spi-imx.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-imx.c b/drivers/spi/spi-imx.c
index 272bc871a848b..546cdce525fc5 100644
--- a/drivers/spi/spi-imx.c
+++ b/drivers/spi/spi-imx.c
@@ -1344,7 +1344,7 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx,
 	controller->dma_tx = dma_request_chan(dev, "tx");
 	if (IS_ERR(controller->dma_tx)) {
 		ret = PTR_ERR(controller->dma_tx);
-		dev_dbg(dev, "can't get the TX DMA channel, error %d!\n", ret);
+		dev_err_probe(dev, ret, "can't get the TX DMA channel!\n");
 		controller->dma_tx = NULL;
 		goto err;
 	}
@@ -1353,7 +1353,7 @@ static int spi_imx_sdma_init(struct device *dev, struct spi_imx_data *spi_imx,
 	controller->dma_rx = dma_request_chan(dev, "rx");
 	if (IS_ERR(controller->dma_rx)) {
 		ret = PTR_ERR(controller->dma_rx);
-		dev_dbg(dev, "can't get the RX DMA channel, error %d\n", ret);
+		dev_err_probe(dev, ret, "can't get the RX DMA channel!\n");
 		controller->dma_rx = NULL;
 		goto err;
 	}
-- 
2.34.1