[PATCH 0/2] rtc: Prevent hctosys from using invalid RTC time

[Akashdeep Kaur]

The kernel's boot-time RTC synchronization blindly trusts the RTC 
value when setting system time, but RTCs may have invalid time 
depending on the boot path:

- On first cold boot: RTC may have lost power, time is invalid
- After low-power mode (RTC-only) cold boot: RTC retained power, time 
  is valid

On normal cold boot where bootloader or NTP has already established 
correct time, boot-time sync (triggered when RTC driver loads as 
module or probes at boot) can overwrite it with invalid RTC data, 
causing time rollback to 1970. However, on boot from RTC-only power 
mode, the RTC has valid time and boot-time sync should work to 
restore system time from RTC.

This series adds a flag that drivers set dynamically per-boot to 
indicate whether RTC has valid time. Drivers check at probe if RTC 
retained power through this specific boot. Boot-time sync checks this 
flag before setting system time. This enables correct behavior for 
both boot paths while keeping PM suspend/resume compensation 
unaffected.

---

Akashdeep Kaur (2):
  rtc: Add flag for dynamic hctosys control
  rtc: ti-k3: Mark RTC time as invalid without battery backup

 drivers/rtc/class.c     | 15 +++++++++++++++
 drivers/rtc/rtc-ti-k3.c |  7 +++++++
 include/linux/rtc.h     |  7 +++++++
 3 files changed, 29 insertions(+)


base-commit: 8f7df005a7564bd7ffa75da9c3085d5b996f1e16
-- 
2.34.1