Re: [PATCH] media: xilinx: Use dma_request_chan() instead dma_request_slave_channel()

On 09/01/2020 18.53, Laurent Pinchart wrote:

Hello again,

On Thu, Jan 09, 2020 at 06:48:47PM +0200, Laurent Pinchart wrote:

quoted

On Tue, Dec 17, 2019 at 12:42:35PM +0200, Peter Ujfalusi wrote:

quoted

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 <redacted>

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Vinod, could you please pick this up ?

I spoke too fast.

quoted

quoted

---
 drivers/media/platform/xilinx/xilinx-dma.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/media/platform/xilinx/xilinx-dma.c b/drivers/media/platform/xilinx/xilinx-dma.c
index b211380a11f2..9ce515ff9c0a 100644
--- a/drivers/media/platform/xilinx/xilinx-dma.c
+++ b/drivers/media/platform/xilinx/xilinx-dma.c

@@ -725,10 +725,10 @@ int xvip_dma_init(struct xvip_composite_device *xdev, struct xvip_dma *dma,
 
 	/* ... and the DMA channel. */
 	snprintf(name, sizeof(name), "port%u", port);
-	dma->dma = dma_request_slave_channel(dma->xdev->dev, name);
-	if (dma->dma == NULL) {
+	dma->dma = dma_request_chan(dma->xdev->dev, name);
+	if (IS_ERR(dma->dma)) {
 		dev_err(dma->xdev->dev, "no VDMA channel found\n");

and print this only in case of !EPROBE_DEFER

quoted

quoted

-		ret = -ENODEV;
+		ret = PTR_ERR(dma->dma);
 		goto error;

At the error label, we have

error:
	xvip_dma_cleanup(dma);
	return ret;

and xvip_dma_cleanup() contains

	if (dma->dma)
		dma_release_channel(dma->dma);

You need to turn this into

	if (!IS_ERR_OR_NULL(dma->dma))

I generally try to avoid IS_ERR_OR_NULL()

or add a

		dma->dma = NULL;

But in this case I think it looks better that way.

in the error case in xvip_dma_init().

quoted

quoted

 	}
 

- Péter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki

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