netdev - Re: [PATCH V2 01/14] clk: add helper functions clk_prepare_enable and clk_disable

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Date:	Fri, 11 Nov 2011 10:15:56 +0100
From:	Sascha Hauer <s.hauer@...gutronix.de>
To:	Richard Zhao <richard.zhao@...aro.org>
Cc:	amit.kucheria@...onical.com, linux@....linux.org.uk,
	kernel@...gutronix.de, netdev@...r.kernel.org,
	linux-mmc@...r.kernel.org, ben-linux@...ff.org,
	eric.miao@...aro.org, linux-i2c@...r.kernel.org,
	linux-serial@...r.kernel.org, cjb@...top.org,
	linux-arm-kernel@...ts.infradead.org, alan@...ux.intel.com
Subject: Re: [PATCH V2 01/14] clk: add helper functions clk_prepare_enable
 and clk_disable_unprepare

On Fri, Nov 11, 2011 at 05:05:47PM +0800, Richard Zhao wrote:
> On Fri, Nov 11, 2011 at 09:49:50AM +0100, Sascha Hauer wrote:
> > On Fri, Nov 11, 2011 at 09:10:16AM +0800, Richard Zhao wrote:
> > > Signed-off-by: Richard Zhao <richard.zhao@...aro.org>
> > > ---
> > >  include/linux/clk.h |   19 +++++++++++++++++++
> > >  1 files changed, 19 insertions(+), 0 deletions(-)
> > > 
> > > diff --git a/include/linux/clk.h b/include/linux/clk.h
> > > index 7213b52..63985f7 100644
> > > --- a/include/linux/clk.h
> > > +++ b/include/linux/clk.h
> > > @@ -107,6 +107,25 @@ static inline void clk_unprepare(struct clk *clk)
> > >  }
> > >  #endif
> > >  
> > > +static inline int clk_prepare_enable(struct clk *clk)
> > > +{
> > > +	int ret;
> > > +
> > > +	ret = clk_prepare(clk);
> > > +	if (!ret)
> > > +		ret = clk_enable(clk);
> > > +	if (ret)
> > > +		clk_unprepare(clk);
> > 
> > As Baruch already pointed out this is hard to read. Also it contains a
> > bug. When clk_prepare fails clk_unprepare is called afterwards.
> > 
> > Hint: Kernel guys are not afraid of having multiple return statements
> > in a function, instead they like it when something is handled early
> > without having to read the rest of the function.
> {
> 	int ret;
> 
> 	ret = clk_prepare(clk);
> 	if (ret)
> 		return ret;
> 	ret = clk_enable(clk);
> 	if (ret)
> 		clk_unprepare(clk);
> 	return ret;

Yes, looks good.

Sascha

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