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

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Date:   Thu, 9 Jan 2020 18:53:48 +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
Subject: Re: [PATCH] media: xilinx: Use dma_request_chan() instead
 dma_request_slave_channel()

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

or add a

		dma->dma = NULL;

in the error case in xvip_dma_init().

> >  	}
> >  

-- 
Regards,

Laurent Pinchart