Subject: Re: clock skew on B/W G3

From: Marc <[email-masked]>
Date: Wed, 5 Oct 2005 08:34:35 +0200

Hi Ben, 

Le Mittwoch 05 Oktober 2005 00:14, Benjamin Herrenschmidt a écrit :
> The problem is indeed in via_calibrate_decr(). This routine works on
> HZ/100 so it will not do any good with HZ not beeing a multiple of 100.
>
> Can you test this patch ?

I can confirm that this patch solves the timer skew on my mac.

Thanks!

>
> Index: linux-work/arch/ppc/platforms/pmac_time.c
> ===================================================================
> --- linux-work.orig/arch/ppc/platforms/pmac_time.c	2005-09-22
> 14:06:18.000000000 +1000 +++
> linux-work/arch/ppc/platforms/pmac_time.c	2005-10-05 08:14:17.000000000
> +1000 @@ -195,7 +195,7 @@
>  		;
>  	dend = get_dec();
>
> -	tb_ticks_per_jiffy = (dstart - dend) / (6 * (HZ/100));
> +	tb_ticks_per_jiffy = (dstart - dend) / ((6 * HZ)/100);
>  	tb_to_us = mulhwu_scale_factor(dstart - dend, 60000);
>
>  	printk(KERN_INFO "via_calibrate_decr: ticks per jiffy = %u (%u ticks)\n",
>
>
> -
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