[CPUFREQ] Longhaul - Fix guess_fsb function
This is bug reported by John-Marc Chandonia:
> Detected 1002.292 MHz processor.
> longhaul: VIA C3 'Nehemiah B' [C5N] CPU detected. Powersaver supported.
> longhaul: Using throttling support.
> longhaul: Invalid (reserved) FSB!
FSB is correcly guessed for 999.554 MHz CPU.
To fix this error:
- ROUNDING should be range, not mask - at it's current value it is +7 -8,
- more precise calculations inside guess_fsb - 7.5x133MHz is 1000MHz now.
Signed-off-by: Rafal Bilski <rafalbilski@interia.pl>
Signed-off-by: Dave Jones <davej@redhat.com>
diff --git a/arch/i386/kernel/cpu/cpufreq/longhaul.c b/arch/i386/kernel/cpu/cpufreq/longhaul.c
index 8ea34e9..8b5ad30 100644
--- a/arch/i386/kernel/cpu/cpufreq/longhaul.c
+++ b/arch/i386/kernel/cpu/cpufreq/longhaul.c
@@ -318,31 +318,19 @@
#define ROUNDING 0xf
-static int _guess(int guess, int mult)
-{
- int target;
-
- target = ((mult/10)*guess);
- if (mult%10 != 0)
- target += (guess/2);
- target += ROUNDING/2;
- target &= ~ROUNDING;
- return target;
-}
-
-
static int guess_fsb(int mult)
{
- int speed = (cpu_khz/1000);
+ int speed = cpu_khz / 1000;
int i;
- int speeds[] = { 66, 100, 133, 200 };
+ int speeds[] = { 666, 1000, 1333, 2000 };
+ int f_max, f_min;
- speed += ROUNDING/2;
- speed &= ~ROUNDING;
-
- for (i=0; i<4; i++) {
- if (_guess(speeds[i], mult) == speed)
- return speeds[i];
+ for (i = 0; i < 4; i++) {
+ f_max = ((speeds[i] * mult) + 50) / 100;
+ f_max += (ROUNDING / 2);
+ f_min = f_max - ROUNDING;
+ if ((speed <= f_max) && (speed >= f_min))
+ return speeds[i] / 10;
}
return 0;
}