linux-kernel - Re: [PATCHv2 2/3] ARM: Allow machines to override _

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Message-ID: <1289000592.15381.23.camel@m0nster>
Date:	Fri, 05 Nov 2010 16:43:12 -0700
From:	Daniel Walker <dwalker@...eaurora.org>
To:	Stephen Boyd <sboyd@...eaurora.org>
Cc:	Russell King <linux@....linux.org.uk>,
	Nicolas Pitre <nico@...xnic.net>,
	Kevin Hilman <khilman@...prootsystems.com>,
	linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Saravana Kannan <skannan@...eaurora.org>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Colin Cross <ccross@...roid.com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCHv2 2/3] ARM: Allow machines to override __delay()

On Fri, 2010-11-05 at 14:51 -0700, Stephen Boyd wrote:
> On 11/04/2010 02:16 PM, Daniel Walker wrote:
> > On Thu, 2010-11-04 at 13:58 -0700, Stephen Boyd wrote:
> >> Wouldn't that mean delay_fn needs to be exposed in the header file too?
> >> I like the fact that it's static and scoped to this file.
> >
> > Yeah you would need to make an extern for that. Why is it better to have
> > it static in this file?
> >
> > If you make it inline you should have smaller code size since all your
> > doing is "delay_fn = fn;" and that's not expected to be used much (if at
> > all).
> >
> 
> Ok. Doing that increases the size of my vmlinux.
> 
> $ size vmlinux.orig vmlinux.new
>    text    data     bss     dec     hex filename
> 7091426  594512 1244648 8930586  88451a vmlinux.orig
> 7091514  594512 1244648 8930674  884572 vmlinux.new

This is what I get,

   text    data     bss     dec     hex filename
2168427  104288  186176 2458891  25850b ../build-test/vmlinux.orig
2168379  104288  186176 2458843  2584db ../build-test/vmlinux.new

Your patch has something wrong with it, which I fixed. Details below,

> Here's the interdiff.
> 
> diff --git a/arch/arm/include/asm/delay.h b/arch/arm/include/asm/delay.h
> index 5c6b9a3..ef0ea48 100644
> --- a/arch/arm/include/asm/delay.h
> +++ b/arch/arm/include/asm/delay.h
> @@ -8,7 +8,20 @@
>  
>  #include <asm/param.h>	/* HZ */
>  
> -extern void __delay(unsigned long loops);
> +extern void (*delay_fn)(unsigned long);
> +
> +static inline void set_delay_fn(void (*fn)(unsigned long))
> +{
> +	delay_fn = fn;
> +}
> +
> +/*
> + * loops = usecs * HZ * loops_per_jiffy / 1000000
> + */
> +static inline void __delay(unsigned long loops)
> +{
> +	delay_fn(loops);
> +}
>  
>  /*
>   * This function intentionally does not exist; if you see references to
> @@ -40,7 +53,6 @@ extern void __const_udelay(unsigned long);
>  			__const_udelay((n) * ((2199023U*HZ)>>11))) :	\
>  	  __udelay(n))
>  
> -extern void set_delay_fn(void (*fn)(unsigned long));
>  extern void read_current_timer_delay_loop(unsigned long loops);
>  
>  #endif /* defined(_ARM_DELAY_H) */
> diff --git a/arch/arm/lib/delay.c b/arch/arm/lib/delay.c
> index 59fdf64..a4b1ecd 100644
> --- a/arch/arm/lib/delay.c
> +++ b/arch/arm/lib/delay.c
> @@ -44,20 +44,8 @@ void read_current_timer_delay_loop(unsigned long loops)
>  }
>  #endif
>  
> -static void (*delay_fn)(unsigned long) = delay_loop;
> +void (*delay_fn)(unsigned long) = delay_loop;
>  
> -void set_delay_fn(void (*fn)(unsigned long))
> -{
> -	delay_fn = fn;
> -}
> -
> -/*
> - * loops = usecs * HZ * loops_per_jiffy / 1000000
> - */
> -void __delay(unsigned long loops)
> -{
> -	delay_fn(loops);
> -}
>  EXPORT_SYMBOL(__delay);

You need to modify this EXPORT_SYMBOL to delay_fn since __delay doesn't
exist anymore.

Daniel

-- 
Sent by an consultant of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
Forum.


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