The code to calibrate TSC frequency from the PM timer does not work on my
laptop with the 2.6.21-rt5.
[ 0.247815] time.c: Detected 62117.606 MHz processor.
The code looks to be copied from the calibration from HPET but unfortunately
it reports frequency instead of period in femtoseconds as the HPET does. I
also rearranged the math to make the femtoseconds and kHz clearer but it does
loose a negligible amount of precision.
Signed-off-by: Joachim Deguara <[EMAIL PROTECTED]>
Index: 2.6-rt/arch/x86_64/kernel/tsc.c
===================================================================
--- 2.6-rt.orig/arch/x86_64/kernel/tsc.c
+++ 2.6-rt/arch/x86_64/kernel/tsc.c
@@ -187,14 +187,14 @@ void __init tsc_calibrate(void)
return;
}
- tsc2 = (tsc2 - tsc1) * 1000000000L;
+ tsc2 = tsc2 - tsc1;
if (hpet) {
hpet2 = (hpet2 - hpet1) & 0xFFFFFFFF;
- tsc1 = (hpet2 * hpet_readl(HPET_PERIOD)) / 1000;
+ tsc1 = hpet2 * hpet_readl(HPET_PERIOD) / 1e12;
} else {
pm2 = (pm2 -pm1) & ACPI_PM_MASK;
- tsc1 = (pm2 * PMTMR_TICKS_PER_SEC) / 1000;
+ tsc1 = (pm2 * 1e3) / PMTMR_TICKS_PER_SEC;
}
tsc_khz = tsc2 / tsc1;
-
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