sravan/system76-edk2
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

UefiCpuPkg/CpuDxe: Fix hard code actual TimerPeriod value

Browse Source 
Current CpuGetTimerValue() implementation return hard code TimerPeriod value. We
could calculate the actual TimerPeriod value over period of time (100us) at the
first time invoking CpuGetTimerValue() and save the TimerPeriod value into one
global variable to avoid delay at the next CpuGetTimerValue() invoking.

https://bugzilla.tianocore.org/show_bug.cgi?id=382

Cc: Feng Tian <feng.tian@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Fan <jeff.fan@intel.com>
Reviewed-by: Feng Tian <feng.tian@Intel.com>
This commit is contained in:
Jeff Fan
2017-02-20 16:17:05 +08:00
parent 14f92ded90
commit 7537f8c09a
3 changed files with 25 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

24
UefiCpuPkg/CpuDxe/CpuDxe.c
View File

@@ -27,6 +27,7 @@ EFI_HANDLE mCpuHandle = NULL;
BOOLEAN mIsFlushingGCD;
UINT64 mValidMtrrAddressMask = MTRR_LIB_CACHE_VALID_ADDRESS;
UINT64 mValidMtrrBitsMask = MTRR_LIB_MSR_VALID_MASK;
UINT64 mTimerPeriod = 0;
FIXED_MTRR mFixedMtrrTable[] = {
{
@@ -297,6 +298,9 @@ CpuGetTimerValue (
OUT UINT64 *TimerPeriod OPTIONAL
)
{
UINT64 BeginValue;
UINT64 EndValue;
if (TimerValue == NULL) {
return EFI_INVALID_PARAMETER;
}
@@ -308,10 +312,26 @@ CpuGetTimerValue (
*TimerValue = AsmReadTsc ();
if (TimerPeriod != NULL) {
if (mTimerPeriod == 0) {
//
// BugBug: Hard coded. Don't know how to do this generically
// Read time stamp counter before and after delay of 100 microseconds
//
*TimerPeriod = 1000000000;
BeginValue = AsmReadTsc ();
MicroSecondDelay (100);
EndValue = AsmReadTsc ();
//
// Calculate the actual frequency
//
mTimerPeriod = DivU64x64Remainder (
MultU64x32 (
1000 * 1000 * 1000,
100
),
EndValue - BeginValue,
NULL
);
}
*TimerPeriod = mTimerPeriod;
}
return EFI_SUCCESS;