linux-kernel - Re: [PATCH v2] media: xilinx: Use dma_request_chan() instead dma_request_slave

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Date:   Wed, 15 Jan 2020 19:28:22 +0200
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Peter Ujfalusi <peter.ujfalusi@...com>
Cc:     mchehab@...nel.org, hyun.kwon@...inx.com, vkoul@...nel.org,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        michal.simek@...inx.com, linux-arm-kernel@...ts.infradead.org,
        Hans Verkuil <hverkuil@...all.nl>
Subject: Re: [PATCH v2] media: xilinx: Use dma_request_chan() instead
 dma_request_slave_channel()

Hi Peter,

(CC'ing Hans)

Thank you for the patch.

On Fri, Jan 10, 2020 at 09:16:48AM +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@...com>

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

and taken in my tree. Hans, you asked me on IRC to review this, did you
plan to get it merged upstream yourself ? If so I'll drop it.

> ---
> Hi,
> 
> Changes since v1:
> - Fix cleanup path when DMA request failed as suggested by Laurent
> - Print error only in case when the error is not EPROBE_DEFER
> 
>  drivers/media/platform/xilinx/xilinx-dma.c | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/media/platform/xilinx/xilinx-dma.c b/drivers/media/platform/xilinx/xilinx-dma.c
> index b211380a11f2..3bb54a4db6a4 100644
> --- a/drivers/media/platform/xilinx/xilinx-dma.c
> +++ b/drivers/media/platform/xilinx/xilinx-dma.c
> @@ -725,10 +725,11 @@ 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) {
> -		dev_err(dma->xdev->dev, "no VDMA channel found\n");
> -		ret = -ENODEV;
> +	dma->dma = dma_request_chan(dma->xdev->dev, name);
> +	if (IS_ERR(dma->dma)) {
> +		ret = PTR_ERR(dma->dma);
> +		if (ret != -EPROBE_DEFER)
> +			dev_err(dma->xdev->dev, "no VDMA channel found\n");
>  		goto error;
>  	}
>  
> @@ -752,7 +753,7 @@ void xvip_dma_cleanup(struct xvip_dma *dma)
>  	if (video_is_registered(&dma->video))
>  		video_unregister_device(&dma->video);
>  
> -	if (dma->dma)
> +	if (!IS_ERR_OR_NULL(dma->dma))
>  		dma_release_channel(dma->dma);
>  
>  	media_entity_cleanup(&dma->video.entity);

-- 
Regards,

Laurent Pinchart