[PATCH RFC 0/3] alarmtimer: Choose the wakeup RTC per sleep state from the device tree

[Igor Velkov]

On 11/4/26, Neil Armstrong wrote:
> This sounds bulky, perhaps it would be much simpler if we just added
> all the available RTCs which has RTC_FEATURE_ALARM and can wakeup ?
>
> Just switch from 1 single to multiple RTCs in a linked list and you're
> done, no DT & bindings changes.

A list it is, and v2 drops linux,alarmtimer-priority.

Arming every RTC makes the coarsest one fire first: pcf8563 has no
alarm seconds, so its alarm comes up to 59 s early, and an RTC with
alarm_offset_max wakes earlier still. The board wakes before the timer
expires, and the next alarm may come seconds later: while it is still
resuming, which takes seconds with disks and PCIe, or right after it
is suspended again. Drivers then go through suspend and resume at
short intervals. Arming one RTC per sleep state avoids that, and which
RTC wakes from which state is board knowledge, so v2 keeps
linux,wakeup-states.

--
Igor Velkov