[POWERPC] Fix off-by-one error in setting decrementer on Book E

[Kumar Gala]

On Oct 28, 2007, at 9:57 PM, Paul Mackerras wrote:

> The decrementer in Book E and 4xx processors interrupts on the
> transition from 1 to 0, rather than on the 0 to -1 transition as on
> 64-bit server and 32-bit "classic" (6xx/7xx/7xxx) processors.
>
> This fixes the problem by making set_dec subtract 1 from the count for
> server and classic processors.  Since set_dec already had a bunch of
> ifdefs to handle different processor types, there is no net increase
> in ugliness. :)
>
> This also removes a redundant call to set the decrementer to
> 0x7fffffff - it was already set to that earlier in timer_interrupt.
>
> Signed-off-by: Paul Mackerras <paulus at samba.org>
> ---

...

> diff --git a/include/asm-powerpc/time.h b/include/asm-powerpc/time.h
> index f058955..eed64bd 100644
> --- a/include/asm-powerpc/time.h
> +++ b/include/asm-powerpc/time.h
> @@ -183,6 +183,7 @@ static inline void set_dec(int val)
>  #elif defined(CONFIG_8xx_CPU6)
>  	set_dec_cpu6(val);
>  #else
> +	--val;	/* classic decrementer interrupts when dec goes negative */
>  #ifdef CONFIG_PPC_ISERIES
>  	int cur_dec;
>

Unless I'm reading set_dec() you are getting --val on booke.

- k