Reviewed-by: Ray Ni <ray...@intel.com> > -----Original Message----- > From: Chao, Zhuoran <zhuoran.c...@intel.com> > Sent: Saturday, May 7, 2022 5:40 PM > To: devel@edk2.groups.io > Cc: Chao, Zhuoran <zhuoran.c...@intel.com>; Ni, Ray <ray...@intel.com> > Subject: [PATCH v3] PcAtChipsetPkg: Change the flow of PcRtcInit() > > REF:https://bugzilla.tianocore.org/show_bug.cgi?id=3913 > > The original flow of PcRtcInit() is like: > 1. Guarantee atomic accesses to the RTC time registers and > read out the value. > 2. Program RTC register B. (adopt 12h mode or 24h mode. Current > bios code sets RTC to 24h mode by default). > 3. Then function ConvertRtcTimeToEfiTime converts the RTC time > value to their 24h mode by checking the hour format bit > (1:24h mode,0:12h mode). > And here lies the problem: Step3 will fail to adjust the value > if Step2 already sets RTC to 24h mode. The hour value in 12h mode > will not be converted to its 24h mode. > The solution is to program RTC register B a little later when all > the original RTC registers' value is retrieved, adjusted > and validated. > > ConvertRtcTimeToEfiTime is modified to be more robust. > > Cc: Ray Ni <ray...@intel.com> > > Signed-off-by: Zhuoran Chao <zhuoran.c...@intel.com> > --- > .../PcatRealTimeClockRuntimeDxe/PcRtc.c | 29 ++++++++++--------- > 1 file changed, 16 insertions(+), 13 deletions(-) > > diff --git a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c > b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c > index 0fbfa4bcee..9242a2e826 100644 > --- a/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c > +++ b/PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c > @@ -269,13 +269,6 @@ PcRtcInit ( > Time.Month = RtcRead (RTC_ADDRESS_MONTH); > Time.Year = RtcRead (RTC_ADDRESS_YEAR); > > - // > - // Set RTC configuration after get original time > - // The value of bit AIE should be reserved. > - // > - RegisterB.Data = FixedPcdGet8 (PcdInitialValueRtcRegisterB) | > (RegisterB.Data & BIT5); > - RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data); > - > // > // Release RTC Lock. > // > @@ -330,6 +323,13 @@ PcRtcInit ( > Time.Daylight = 0; > } > > + // > + // Set RTC configuration after get original time > + // The value of bit AIE should be reserved. > + // > + RegisterB.Data = FixedPcdGet8 (PcdInitialValueRtcRegisterB) | > (RegisterB.Data & BIT5); > + RtcWrite (RTC_ADDRESS_REGISTER_B, RegisterB.Data); > + > // > // Reset time value according to new RTC configuration > // > @@ -995,13 +995,16 @@ ConvertRtcTimeToEfiTime ( > BOOLEAN IsPM; > UINT8 Century; > > - if ((Time->Hour & 0x80) != 0) { > - IsPM = TRUE; > - } else { > - IsPM = FALSE; > - } > + // IsPM only makes sense for 12-hour format. > + if (RegisterB.Bits.Mil == 0) { > + if ((Time->Hour & 0x80) != 0) { > + IsPM = TRUE; > + } else { > + IsPM = FALSE; > + } > > - Time->Hour = (UINT8)(Time->Hour & 0x7f); > + Time->Hour = (UINT8)(Time->Hour & 0x7f); > + } > > if (RegisterB.Bits.Dm == 0) { > Time->Year = CheckAndConvertBcd8ToDecimal8 ((UINT8)Time->Year); > -- > 2.31.1.windows.1
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