linux-kernel - Re: [PATCH] media: stm32-dcmi: simplify of_node

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Date:   Mon, 18 Jun 2018 09:36:28 +0000
From:   Hugues FRUCHET <hugues.fruchet@...com>
To:     Nicholas Mc Guire <hofrat@...dl.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
CC:     Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre TORGUE <alexandre.torgue@...com>,
        Hans Verkuil <hans.verkuil@...co.com>,
        "Philipp Zabel" <p.zabel@...gutronix.de>,
        Niklas Soderlund <niklas.soderlund+renesas@...natech.se>,
        Benjamin Gaignard <benjamin.gaignard@...aro.org>,
        "Gustavo A. R. Silva" <garsilva@...eddedor.com>,
        "linux-media@...r.kernel.org" <linux-media@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] media: stm32-dcmi: simplify of_node_put usage

Hi Nicholas,
Thanks for patch,

On 06/12/2018 07:23 PM, Nicholas Mc Guire wrote:
> This does not fix any bug - this is just a code simplification. As
> np is not used after passing it to v4l2_fwnode_endpoint_parse() its
> refcount can be decremented immediately and at one location.
> 
> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
Acked-by: Hugues Fruchet <hugues.fruchet@...com>

> ---
> 
> Issue found during code reading.
> 
> Patch was compile tested with: x86_64_defconfig, MEDIA_SUPPORT=y
> MEDIA_CAMERA_SUPPORT=y, V4L_PLATFORM_DRIVERS=y, OF=y, COMPILE_TEST=y
> CONFIG_VIDEO_STM32_DCMI=y
> (There are a few sparse warnings - but unrelated to the lines changed)
> 
> Patch is against 4.17.0 (localversion-next is next-20180608)
> 
>   drivers/media/platform/stm32/stm32-dcmi.c | 5 +----
>   1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/media/platform/stm32/stm32-dcmi.c b/drivers/media/platform/stm32/stm32-dcmi.c
> index 2e1933d..0b61042 100644
> --- a/drivers/media/platform/stm32/stm32-dcmi.c
> +++ b/drivers/media/platform/stm32/stm32-dcmi.c
> @@ -1696,23 +1696,20 @@ static int dcmi_probe(struct platform_device *pdev)
>   	}
>   
>   	ret = v4l2_fwnode_endpoint_parse(of_fwnode_handle(np), &ep);
> +	of_node_put(np);
>   	if (ret) {
>   		dev_err(&pdev->dev, "Could not parse the endpoint\n");
> -		of_node_put(np);
>   		return -ENODEV;
>   	}
>   
>   	if (ep.bus_type == V4L2_MBUS_CSI2) {
>   		dev_err(&pdev->dev, "CSI bus not supported\n");
> -		of_node_put(np);
>   		return -ENODEV;
>   	}
>   	dcmi->bus.flags = ep.bus.parallel.flags;
>   	dcmi->bus.bus_width = ep.bus.parallel.bus_width;
>   	dcmi->bus.data_shift = ep.bus.parallel.data_shift;
>   
> -	of_node_put(np);
> -
>   	irq = platform_get_irq(pdev, 0);
>   	if (irq <= 0) {
>   		dev_err(&pdev->dev, "Could not get irq\n");
>