[edk2-devel] [PATCH v3] PcAtChipsetPkg: Change the flow of PcRtcInit()
Ni, Ray
ray.ni at intel.com
Sat May 7 15:16:04 UTC 2022
Reviewed-by: Ray Ni <ray.ni at intel.com>
> -----Original Message-----
> From: Chao, Zhuoran <zhuoran.chao at intel.com>
> Sent: Saturday, May 7, 2022 5:40 PM
> To: devel at edk2.groups.io
> Cc: Chao, Zhuoran <zhuoran.chao at intel.com>; Ni, Ray <ray.ni at 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.ni at intel.com>
>
> Signed-off-by: Zhuoran Chao <zhuoran.chao at 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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