linux-kernel - Re: [PATCH] of: Turn of_match_node into a static inline when CONFIG

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Message-ID: <1596542.hkJp71u3OJ@avalon>
Date:	Tue, 11 Feb 2014 15:55:35 +0100
From:	Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:	Josh Cartwright <joshc@...eaurora.org>
Cc:	linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCH] of: Turn of_match_node into a static inline when CONFIG_OF isn't set

Hi Josh,

On Tuesday 11 February 2014 08:41:08 Josh Cartwright wrote:
> On Tue, Feb 11, 2014 at 01:36:51PM +0100, Laurent Pinchart wrote:
> > when CONFIG_OF is disabled of_match_node is defined as a macro that
> > evaluates to NULL. This breaks compilation of drivers that dereference
> > the function's return value directly. Fix it by turning the macro into a
> > static inline function that returns NULL.
> 
> Just this past week I did the same thing, but noticed that it breaks the
> following usecase:
> 
> 	#ifdef CONFIG_OF
> 	static const struct of_device_id foobar_matches[] = {
> 		{ .compatible = "foobar,whatsit", },
> 		{ },
> 	};
> 	#endif
> 
> 	static int probeme(struct platform_device *pdev)
> 	{
> 		struct of_device_id *id;
> 
> 		id = of_match_node(foobar_matches, pdev->dev.of_node);
> 		if (id) {
> 			/* ... */
> 		}
> 		return 0;
> 	}
> 
> When !CONFIG_OF and with your change, this will fail to build due to
> foobar_matches being undefined.

Good point. What would you think about

#define of_match_node(_matches, _node)  ((const struct of_device_id *)NULL)

?

-- 
Regards,

Laurent Pinchart

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