[alsa-devel] [PATCH] ASoC: prevent compilers from optimising pll calculation into __aeabi__uldivmod

[Takashi Iwai]

At Wed, 27 Apr 2011 00:27:32 -0700,
Barry Song wrote:
> 
> From: Barry Song <21cnbao at gmail.com>
> 
> The newest compiliers can optimize pll calculation in several codecs into __aeabi__uldivmod which doesn't exist in kernel.
> Then the link will fail:
> ERROR: "__aeabi_uldivmod" [sound/soc/codecs/snd-soc-wm8974.ko] undefined!
> ERROR: "__aeabi_uldivmod" [sound/soc/codecs/snd-soc-wm8940.ko] undefined!
> ERROR: "__aeabi_uldivmod" [sound/soc/codecs/snd-soc-wm8510.ko] undefined!
> This patch prevent the optimizaton by insert ASM.

Don't do this in the low driver level.  If any, we should fix do_div()
instead.


thanks,

Takashi

> 
> Signed-off-by: Barry Song <21cnbao at gmail.com>
> Cc: Zhiwu Song <zhiwu.song at csr.com>
> Cc: Binghua Duan <binghua.duan at csr.com>
> ---
>  sound/soc/codecs/wm8510.c |    6 ++++++
>  sound/soc/codecs/wm8940.c |    6 ++++++
>  sound/soc/codecs/wm8974.c |    6 ++++++
>  3 files changed, 18 insertions(+), 0 deletions(-)
> 
> diff --git a/sound/soc/codecs/wm8510.c b/sound/soc/codecs/wm8510.c
> index db0dced..a636b15 100644
> --- a/sound/soc/codecs/wm8510.c
> +++ b/sound/soc/codecs/wm8510.c
> @@ -258,6 +258,12 @@ static void pll_factors(unsigned int target, unsigned int source)
>  	Nmod = target % source;
>  	Kpart = FIXED_PLL_SIZE * (long long)Nmod;
>  
> +	/*
> +	 * The following asm() prevents the compiler from optimising
> +	 * into a standard EABI function __aeabi__uldivmod()
> +	 */
> +	asm("" : "+r"(source));
> +
>  	do_div(Kpart, source);
>  
>  	K = Kpart & 0xFFFFFFFF;
> diff --git a/sound/soc/codecs/wm8940.c b/sound/soc/codecs/wm8940.c
> index 25580e3..f6148af 100644
> --- a/sound/soc/codecs/wm8940.c
> +++ b/sound/soc/codecs/wm8940.c
> @@ -520,6 +520,12 @@ static void pll_factors(unsigned int target, unsigned int source)
>  	Nmod = target % source;
>  	Kpart = FIXED_PLL_SIZE * (long long)Nmod;
>  
> +	/*
> +	 * The following asm() prevents the compiler from optimising
> +	 * into a standard EABI function __aeabi__uldivmod()
> +	 */
> +	asm("" : "+r"(source));
> +
>  	do_div(Kpart, source);
>  
>  	K = Kpart & 0xFFFFFFFF;
> diff --git a/sound/soc/codecs/wm8974.c b/sound/soc/codecs/wm8974.c
> index ca646a8..c9036d9 100644
> --- a/sound/soc/codecs/wm8974.c
> +++ b/sound/soc/codecs/wm8974.c
> @@ -317,6 +317,12 @@ static void pll_factors(struct pll_ *pll_div,
>  	Nmod = target % source;
>  	Kpart = FIXED_PLL_SIZE * (long long)Nmod;
>  
> +	/*
> +	 * The following asm() prevents the compiler from optimising
> +	 * into a standard EABI function __aeabi__uldivmod()
> +	 */
> +	asm("" : "+r"(source));
> +
>  	do_div(Kpart, source);
>  
>  	K = Kpart & 0xFFFFFFFF;
> -- 
> 1.7.1
> 
> 
> 
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