Branch: refs/heads/master
Home: https://github.com/tianocore/edk2
Commit: df6b43f61b074a9c8c09471b586561ca35370408
https://github.com/tianocore/edk2/commit/df6b43f61b074a9c8c09471b586561ca35370408
Author: Chen Lin Z <lin.z.c...@intel.com>
Date: 2024-11-13 (Wed, 13 Nov 2024)
Changed paths:
M PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
M PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.h
Log Message:
-----------
PcAtChipsetPkg: Use DV bit to stop the RTC first when changing the time
Legacy BIOS design sets only the Update Cycle Inhibit (SET) bit when
changing the RTC time. Update Cycle Inhibit Bit may not be supported
by the backend device (Common I2C RTC device). It could add Division
Chain Select (DV) bit to stop the RTC first (Write to 0x07), Changing
the RTC time and then Set the DV bit back.
Signed-off-by: Di Zhang <di.zh...@intel.com>
Commit: 2839fed575f0eccae7f5a89f7252487dd058b462
https://github.com/tianocore/edk2/commit/2839fed575f0eccae7f5a89f7252487dd058b462
Author: Chen Lin Z <lin.z.c...@intel.com>
Date: 2024-11-13 (Wed, 13 Nov 2024)
Changed paths:
M PcAtChipsetPkg/PcatRealTimeClockRuntimeDxe/PcRtc.c
Log Message:
-----------
PcAtChipsetPkg: Write RTC time in PcRtcInit() only when it is needed
In PcRtcInit(), it always read RTC time and then write it back. It could
potentially cause two issues:
1) There is time gap between read RTC and write RTC, writing RTC time on
every boot could cause RTC time drift after many reboot cycles
2) Writing RTC registers on every boot could cause some unnecessary delay,
slightly impact the boot performance.
The change is only writing RTC time when 1) the current RTC time is not
valid or 2) the RegisterB value is changed.
Signed-off-by: Chen Lin Z <lin.z.c...@intel.com>
Compare: https://github.com/tianocore/edk2/compare/f1674e665c3d...2839fed575f0
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