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SubjectRe: [PATCH] media: xilinx: Use dma_request_chan() instead dma_request_slave_channel()
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On 09/01/2020 18.53, Laurent Pinchart wrote:
> Hello again,
>
> On Thu, Jan 09, 2020 at 06:48:47PM +0200, Laurent Pinchart wrote:
>> On Tue, Dec 17, 2019 at 12:42:35PM +0200, Peter Ujfalusi wrote:
>>> 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>
>>
>> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
>>
>> Vinod, could you please pick this up ?
>
> I spoke too fast.
>
>>> ---
>>> 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

>>> - 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().
>
>>> }
>>>
>

- Péter

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