[acpi-jp 2888] Re: ACPI throttling changes

[Nate Lawson]

On Fri, 12 Dec 2003, Taku YAMAMOTO wrote:
> On Thu, 11 Dec 2003 23:07:42 -0600
> Ryan Sommers <ryans at gamersimpact.com> wrote:
> > Here are my results from testing this patch. It appears as though the
> > stepping "works" for the first step and not again. However, the first
> > step shows a approx. 20% increase, I was expecting something closer to
> > 12.5%.
>
> I think we need (CPU_MAX_SPEED-1) instead of CPU_MAX_SPEED when calculating
> mask value (in acpi_cpu_throttle_set()):
>
> --- src/sys/dev/acpica/acpi_cpu.c.orig	Fri Nov 28 01:32:46 2003
> +++ src/sys/dev/acpica/acpi_cpu.c	Sat Nov 29 20:41:28 2003
> @@ -780,7 +780,7 @@
>  	/* If we're at maximum speed, that's all */
>  	if (speed < CPU_MAX_SPEED) {
>  	    /* Mask the old CLK_VAL off and or-in the new value */
> -	    clk_val = CPU_MAX_SPEED << cpu_duty_offset;
> +	    clk_val = (CPU_MAX_SPEED - 1) << cpu_duty_offset;
>  	    p_cnt &= ~clk_val;
>  	    p_cnt |= (speed << cpu_duty_offset);

Thanks, this was the problem.  I've committed the fix.

-Nate