linux-kernel - Re: [PATCH] mmc: Test bus-width for old MMC devices (v2)

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Date:	Fri, 17 Dec 2010 09:11:47 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	Chris Ball <cjb@...top.org>
Cc:	Philip Rakity <prakity@...vell.com>,
	Aries Lee <arieslee@...cron.com>,
	zhangfei gao <zhangfei.gao@...il.com>,
	Qiming Wu <wuqm@...vell.com>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mmc: Test bus-width for old MMC devices (v2)

At Fri, 17 Dec 2010 03:43:42 +0000,
Chris Ball wrote:
> 
> Hi Philip,
> 
> On Thu, Dec 16, 2010 at 06:33:49PM -0800, Philip Rakity wrote:
> > It is not possible for bus_width to be not initialized.  This would imply ARRAY_SIZE(bus_widths) is 1.  Certainly not true.
> 
> Right, I agree.  We should fix the warning anyway.

Well, this is always a gray-zone question.  One prefers fixing it
either via uninitialized_var() or by setting a bogus value.  But, this
would cover any possible real bug in future.  Thus another prefers
ignoring it, because it's just a compiler bug (mostly of old gcc).

After all, it's up to maintainer, so take as you like :)


thanks,

Takashi


> > We could just initialize by changing
> > +		unsigned idx, bus_width;
> > to
> > +		unsigned idx, bus_width = 0;
> 
> Okay, I've pushed to mmc-next with that change.
> 
> > I wonder what compiler are you using so we can avoid this issue in future.
> 
> Ah, good point -- I was building with a gcc 4.1.2 ARM cross-compiler,
> and using a gcc 4.5.1 cross-build instead avoids the warning.
> 
> Thanks,
> 
> -- 
> Chris Ball   <cjb@...top.org>   <http://printf.net/>
> One Laptop Per Child
> 
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