diff options
Diffstat (limited to 'PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c')
| -rw-r--r-- | PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c | 14 |
1 files changed, 7 insertions, 7 deletions
diff --git a/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c b/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c index 8819ebcfcc..29521f8b22 100644 --- a/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c +++ b/PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c @@ -20,13 +20,13 @@ Calculate TSC frequency.
The TSC counting frequency is determined by comparing how far it counts
- during a 100us period as determined by the ACPI timer. The ACPI timer is
- used because it counts at a known frequency.
- The TSC is sampled, followed by waiting for ACPI_TIMER_FREQUENCY / 10000
- clocks of the ACPI timer, or 100us. The TSC is then sampled again. The
- difference multiplied by 10000 is the TSC frequency. There will be a small
- error because of the overhead of reading the ACPI timer. An attempt is
- made to determine and compensate for this error.
+ during a 101.4 us period as determined by the ACPI timer.
+ The ACPI timer is used because it counts at a known frequency.
+ The TSC is sampled, followed by waiting 363 counts of the ACPI timer,
+ or 101.4 us. The TSC is then sampled again. The difference multiplied by
+ 9861 is the TSC frequency. There will be a small error because of the
+ overhead of reading the ACPI timer. An attempt is made to determine and
+ compensate for this error.
@return The number of TSC counts per second.
|