linux-kernel - Re: [PATCH 1/2] i2c-s3c2410: Rework device type handling

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Message-ID: <20120424144407.GA9007@pengutronix.de>
Date:	Tue, 24 Apr 2012 16:44:07 +0200
From:	Wolfram Sang <w.sang@...gutronix.de>
To:	Karol Lewandowski <k.lewandowsk@...sung.com>
Cc:	m.szyprowski@...sung.com, ben-linux@...ff.org,
	thomas.abraham@...aro.org, linux-kernel@...r.kernel.org,
	linux-i2c@...r.kernel.org, devicetree-discuss@...ts.ozlabs.org,
	linux-samsung-soc@...r.kernel.org, t.stanislaws@...sung.com,
	kyungmin.park@...sung.com, broonie@...nsource.wolfsonmicro.com,
	"grant.likely@...retlab.ca" <grant.likely@...retlab.ca>
Subject: Re: [PATCH 1/2] i2c-s3c2410: Rework device type handling

On Tue, Apr 24, 2012 at 10:40:49AM +0200, Karol Lewandowski wrote:
> On 23.04.2012 20:20, Wolfram Sang wrote:
> 
> Hi!
> 
> >> -static inline int s3c24xx_i2c_is2440(struct s3c24xx_i2c *i2c)
> >> +static inline unsigned int s3c24xx_get_device_quirks(struct platform_device *pdev)
> >>  {
> >> -	struct platform_device *pdev = to_platform_device(i2c->dev);
> >> -	enum s3c24xx_i2c_type type;
> >> -
> >> -#ifdef CONFIG_OF
> >> -	if (i2c->dev->of_node)
> >> -		return of_device_is_compatible(i2c->dev->of_node,
> >> -				"samsung,s3c2440-i2c");
> >> -#endif
> >> +	if (pdev->dev.of_node) {
> >> +		const struct of_device_id *match;
> >> +		match = of_match_node(&s3c24xx_i2c_match, pdev->dev.of_node);
> > 
> > I'd appreciate a comment explaining why match can't be NULL here (as to
> > my understanding, it can't). Or just check for it, but this way it looks
> > a bit fishy and people (hopefully ;)) will ask about it.
> 
> 
> My understanding is that it can't be null for exactly same reason why
> platform_get_device_id(pdev) can't be null either (see below).
> 
> I.e. prerequisite for this code to be run at all (as it's called from
> driver's .probe()) is to be already matched against very same match
> table.

Yes, I agree. Yet, this is not obvious and people might try to fix it
(especially since programs like smatch report it as potentially
dangerous). Ah, whatever, I could simply apply the fix then :) OK.

Regards,

   Wolfram

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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