linux-kernel - Re: [PATCH] V4L/DVB: pxa-camera: Unsigned dma

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Date:	Thu, 11 Sep 2008 13:30:57 +0200 (CEST)
From:	Guennadi Liakhovetski <g.liakhovetski@....de>
To:	roel kluin <roel.kluin@...il.com>
cc:	mchehab@...radead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] V4L/DVB: pxa-camera: Unsigned dma_chans[] cannot be
 negative

On Wed, 10 Sep 2008, roel kluin wrote:

> Unsigned dma_chans[] cannot be negative
> 
> Note that also the third time dma_chans[0] < 0 was tested instead of dma_chans[2]
> 
> Signed-off-by: Roel Kluin <roel.kluin@...il.com>
> ---
> diff --git a/drivers/media/video/pxa_camera.c b/drivers/media/video/pxa_camera.c
> index ead87dd..950a2d4 100644
> --- a/drivers/media/video/pxa_camera.c
> +++ b/drivers/media/video/pxa_camera.c
> @@ -1078,7 +1078,7 @@ static int pxa_camera_probe(struct platform_device *pdev)
>  	struct pxa_camera_dev *pcdev;
>  	struct resource *res;
>  	void __iomem *base;
> -	int irq;
> +	int irq, retval;
>  	int err = 0;

You don't need an extra variable here, please just use err.

>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> @@ -1144,31 +1144,34 @@ static int pxa_camera_probe(struct platform_device *pdev)
>  	pcdev->dev = &pdev->dev;
>  
>  	/* request dma */
> -	pcdev->dma_chans[0] = pxa_request_dma("CI_Y", DMA_PRIO_HIGH,
> +	retval = pxa_request_dma("CI_Y", DMA_PRIO_HIGH,
>  					      pxa_camera_dma_irq_y, pcdev);

also, please align the second line to start behind the opening 
parenthesis:

-	pcdev->dma_chans[0] = pxa_request_dma("CI_Y", DMA_PRIO_HIGH,
- 					      pxa_camera_dma_irq_y, pcdev);
+	err = pxa_request_dma("CI_Y", DMA_PRIO_HIGH,
+			      pxa_camera_dma_irq_y, pcdev);

> -	if (pcdev->dma_chans[0] < 0) {
> +	if (retval < 0) {
>  		dev_err(pcdev->dev, "Can't request DMA for Y\n");
>  		err = -ENOMEM;

...and then remove this overwriting, anyway I don't think -ENOMEM is a 
very good return code here. Just return with what pxa_request_dma 
returned.

>  		goto exit_iounmap;
>  	}
> +	pcdev->dma_chans[0] = retval;
>  	dev_dbg(pcdev->dev, "got DMA channel %d\n", pcdev->dma_chans[0]);
>  
> -	pcdev->dma_chans[1] = pxa_request_dma("CI_U", DMA_PRIO_HIGH,
> +	retval = pxa_request_dma("CI_U", DMA_PRIO_HIGH,
>  					      pxa_camera_dma_irq_u, pcdev);
> -	if (pcdev->dma_chans[1] < 0) {
> +	if (retval < 0) {
>  		dev_err(pcdev->dev, "Can't request DMA for U\n");
>  		err = -ENOMEM;
>  		goto exit_free_dma_y;
>  	}
> +	pcdev->dma_chans[1] = retval;
>  	dev_dbg(pcdev->dev, "got DMA channel (U) %d\n", pcdev->dma_chans[1]);
>  
> -	pcdev->dma_chans[2] = pxa_request_dma("CI_V", DMA_PRIO_HIGH,
> +	retval = pxa_request_dma("CI_V", DMA_PRIO_HIGH,
>  					      pxa_camera_dma_irq_v, pcdev);
> -	if (pcdev->dma_chans[0] < 0) {
> +	if (retval < 0) {
>  		dev_err(pcdev->dev, "Can't request DMA for V\n");
>  		err = -ENOMEM;
>  		goto exit_free_dma_u;
>  	}
> +	pcdev->dma_chans[2] = retval;
>  	dev_dbg(pcdev->dev, "got DMA channel (V) %d\n", pcdev->dma_chans[2]);
>  
>  	DRCMR68 = pcdev->dma_chans[0] | DRCMR_MAPVLD;

Otherwise looks good! Please, resubmit and I'll pass it on to v4l 
maintainer.

Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
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