linux-kernel - Re: [PATCH 27/27] thermal: ti-bandgap: cleanup resource allocation

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Date:	Fri, 26 Jul 2013 11:43:23 -0400
From:	Eduardo Valentin <eduardo.valentin@...com>
To:	Wolfram Sang <wsa@...-dreams.de>
CC:	<linux-kernel@...r.kernel.org>,
	Eduardo Valentin <eduardo.valentin@...com>,
	Zhang Rui <rui.zhang@...el.com>, <linux-pm@...r.kernel.org>
Subject: Re: [PATCH 27/27] thermal: ti-bandgap: cleanup resource allocation

On 23-07-2013 14:02, Wolfram Sang wrote:
> When cleaning up usage of devm_ioremap_resource, I found that resource
> allocation in this driver is ugly and buggy. If resource[0] is not
> found, bgp->base will end up NULL, so OOPS. All other resources get
> ioremapped, but their pointers are discarded, so why bother. So, let's
> keep things simple. Just remap resource[0] and pass the error, if any.
> Compile tested only, due to no hardware.


Nack, this will actually break the driver. This device has several
sections of registers, and not a single io region. Check
Documentation/devicetree/bindings/thermal/ti_soc_thermal.txt for examples.

> 
> Signed-off-by: Wolfram Sang <wsa@...-dreams.de>
> ---
> Please apply via the subsystem-tree.
> 
>  drivers/thermal/ti-soc-thermal/ti-bandgap.c |   20 ++++----------------
>  1 file changed, 4 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/thermal/ti-soc-thermal/ti-bandgap.c b/drivers/thermal/ti-soc-thermal/ti-bandgap.c
> index 9dfd471..416be5d 100644
> --- a/drivers/thermal/ti-soc-thermal/ti-bandgap.c
> +++ b/drivers/thermal/ti-soc-thermal/ti-bandgap.c
> @@ -1130,7 +1130,6 @@ static struct ti_bandgap *ti_bandgap_build(struct platform_device *pdev)
>  	const struct of_device_id *of_id;
>  	struct ti_bandgap *bgp;
>  	struct resource *res;
> -	int i;
>  
>  	/* just for the sake */
>  	if (!node) {
> @@ -1156,21 +1155,10 @@ static struct ti_bandgap *ti_bandgap_build(struct platform_device *pdev)
>  		return ERR_PTR(-ENOMEM);
>  	}
>  
> -	i = 0;
> -	do {
> -		void __iomem *chunk;
> -
> -		res = platform_get_resource(pdev, IORESOURCE_MEM, i);
> -		if (!res)
> -			break;
> -		chunk = devm_ioremap_resource(&pdev->dev, res);
> -		if (i == 0)
> -			bgp->base = chunk;
> -		if (IS_ERR(chunk))
> -			return ERR_CAST(chunk);

In case resource 0 is not found, the error will be repassed.

> -
> -		i++;
> -	} while (res);

And yes, other IORESOURCE_MEM resources are required, depending on chip
version.

> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	bgp->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(bgp->base))
> +		return bgp->base;
>  
>  	if (TI_BANDGAP_HAS(bgp, TSHUT)) {
>  		bgp->tshut_gpio = of_get_gpio(node, 0);
> 


-- 
You have got to be excited about what you are doing. (L. Lamport)

Eduardo Valentin


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