Hi,

this patch did not carry a Cc: stable tag, but the platform device
binding changes it fixes have meanwhile been backported to 6.18.y
(6.18.51), including:

  ACPI: x86/rtc-cmos: Use platform device for driver binding

This fix was not backported with it, so 6.18.51 is now affected by
exactly the problem Nathan reported in

https://lore.kernel.org/linux-acpi/20260303060752.GA2749263@ax162/

On my HP ProBook 445 G8 (AMD) the boot log changed as follows:

6.18.49 (good):
  rtc_cmos 00:00: alarms up to one month, y3k, 114 bytes nvram

6.18.51 (bad):
  rtc_cmos PNP0B00:00: error -ENXIO: IRQ index 0 not found
  rtc_cmos PNP0B00:00: no alarms, y3k, 114 bytes nvram

On stable this is more than a confusing message. Without an IRQ the
RTC has no alarm support, so CLOCK_BOOTTIME_ALARM is not available
and systemd (261) refuses suspend-then-hibernate:

  systemd-logind: CLOCK_BOOTTIME_ALARM is not supported, can't
  perform suspend-then-hibernate.
  Call to SuspendThenHibernate failed: Sleep verb
  'suspend-then-hibernate' is not configured or configuration is
  not supported by kernel

Plain suspend and hibernate still work. RTC wake alarms are also
broken:

  # rtcwake -m no -s 120
  rtcwake: set rtc wake alarm failed: Invalid argument

The fix is in mainline since v7.0 as:

  e9f850ba66cd ("rtc: cmos: Use platform_get_irq_optional() in cmos_platform_probe()")

Stable team, could you please queue it for 6.18.y? Any other stable
series that received the rtc-cmos platform device binding backport
would need it as well.

#regzbot introduced: v6.18.49..v6.18.51
#regzbot title: rtc-cmos: no RTC alarms on x86 in 6.18.y after platform device binding backport
#regzbot fix: rtc: cmos: Use platform_get_irq_optional() in cmos_platform_probe()

Thanks,
Philippe