]> git.proxmox.com Git - mirror_edk2.git/commit - PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
PcAtChipsetPkg AcpiTimerLib: Wait 363 ACPI timer counts to get TSC Freq
authorStar Zeng <star.zeng@intel.com>
Wed, 17 Aug 2016 02:08:31 +0000 (10:08 +0800)
committerStar Zeng <star.zeng@intel.com>
Thu, 18 Aug 2016 03:01:54 +0000 (11:01 +0800)
commita012df5ec643a0c08c2b723a02919a5c9373ca74
tree0f4854b1fdf60840d62fc411a12e6a3403820469
parent7503cd70fb864a5663edb121c9b2488b4c69e7f5
PcAtChipsetPkg AcpiTimerLib: Wait 363 ACPI timer counts to get TSC Freq

Compute the number of ticks to wait to measure TSC frequency.
Instead of (ACPI_TIMER_FREQUENCY / 10000) = 357 and 357 * 10000 = 3570000,
use 363 * 9861 = 3579543 Hz which is within 2 Hz of ACPI_TIMER_FREQUENCY.
363 counts is a calibration time of 101.4 uS.

The idea comes from Michael and Paolo.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul A Lohr <paul.a.lohr@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
PcAtChipsetPkg/Library/AcpiTimerLib/AcpiTimerLib.c
PcAtChipsetPkg/Library/AcpiTimerLib/BaseAcpiTimerLib.c
PcAtChipsetPkg/Library/AcpiTimerLib/DxeAcpiTimerLib.c