Clara BW Standby throws error the kernel refused to enter standby!

[Ciantic]

I have a bunch of these:

06/17/24-18:46:17 INFO  WakeupMgr: scheduling wakeup in 4 -> 1718639181 
Cannot write `mem` to file `/sys/power/state`:	Operation not permitted
06/17/24-18:46:18 WARN  Kobo standby: the kernel refused to enter standby! 
06/17/24-18:46:19 INFO  WakeupMgr: scheduling wakeup in 2 -> 1718639181 
Cannot write `mem` to file `/sys/power/state`:	Operation not permitted
06/17/24-18:46:19 WARN  Kobo standby: the kernel refused to enter standby! 
06/17/24-18:46:20 INFO  WakeupMgr: scheduling wakeup in 1 -> 1718639181 
Cannot write `mem` to file `/sys/power/state`:	Operation not permitted
06/17/24-18:46:20 WARN  Kobo standby: the kernel refused to enter standby! 
06/17/24-18:46:55 INFO  WakeupMgr: scheduling wakeup in 3 -> 1718639218 
Cannot write `mem` to file `/sys/power/state`:	Operation not permitted
06/17/24-18:46:55 WARN  Kobo standby: the kernel refused to enter standby! 
06/17/24-18:46:56 INFO  WakeupMgr: scheduling wakeup in 2 -> 1718639218 
Cannot write `mem` to file `/sys/power/state`:	Operation not permitted
06/17/24-18:46:56 WARN  Kobo standby: the kernel refused to enter standby! 
06/17/24-18:46:58 INFO  WakeupMgr: scheduling wakeup in 295 -> 1718639513 
Cannot write `mem` to file `/sys/power/state`:	Operation not permitted
06/17/24-18:46:59 WARN  Kobo standby: the kernel refused to enter standby! 
06/17/24-18:47:00 INFO  WakeupMgr: scheduling wakeup in 294 -> 1718639514 
Cannot write `mem` to file `/sys/power/state`:	Operation not permitted
06/17/24-18:47:00 WARN  Kobo standby: the kernel refused to enter standby! 
06/17/24-18:47:01 INFO  WakeupMgr: scheduling wakeup in 292 -> 1718639513 
Cannot write `mem` to file `/sys/power/state`:	Operation not permitted
06/17/24-18:47:01 WARN  Kobo standby: the kernel refused to enter standby! 
06/17/24-18:47:03 INFO  WakeupMgr: scheduling wakeup in 290 -> 1718639513 
Cannot write `mem` to file `/sys/power/state`:	Operation not permitted
06/17/24-18:47:03 WARN  Kobo standby: the kernel refused to enter standby! 
06/17/24-18:47:04 INFO  WakeupMgr: scheduling wakeup in 288 -> 1718639512 
Cannot write `mem` to file `/sys/power/state`:	Operation not permitted
06/17/24-18:47:05 WARN  Kobo standby: the kernel refused to enter standby! 
06/17/24-18:47:06 INFO  WakeupMgr: scheduling wakeup in 287 -> 1718639513 
Cannot write `mem` to file `/sys/power/state`:	Operation not permitted
06/17/24-18:47:06 WARN  Kobo standby: the kernel refused to enter standby!

I don't know yet how to interpret this, is it normal when it can't do it, but there is a lot of those. And I don't know if I see any successful ones as I don't know what to search.

If I'm reading this correctly in Clara BW the file used to write is "mem" but maybe it is not:

https://github.com/koreader/koreader...evice.lua#L560

-- Kobo Clara B/W:
local KoboSpaBW = Kobo:extend{
    model = "Kobo_spaBW",
    isMTK = yes,

Then in the logic

    if self:isMTK() then
        self.standby_state = "mem"
    end

Now I'm wondering what happens in Clara BW with

    -- The standard "standby" power state
    standby_state = "standby"

Maybe I have to test it out!

[Ciantic]

I enabled a debug mode.

Apparently it still works sometimes, I can see from logs:

06/17/24-19:28:15 DEBUG AutoSuspend: entering standby with a wakeup alarm in 271 s
06/17/24-19:28:16 INFO WakeupMgr: scheduling wakeup in 271 -> 1718641967
06/17/24-19:28:16 DEBUG WakeupMgr:setWakeupAlarm for 1718641967 (2024-06-17 19:32:47 +0300)
06/17/24-19:28:16 DEBUG Kobo standby: asking to enter standby . . .
06/17/24-19:28:29 DEBUG Kobo standby: zZz zZz zZz zZz... And woke up!
06/17/24-19:28:29 DEBUG AutoSuspend: left standby after 13.135957 s
06/17/24-19:28:29 DEBUG AutoSuspend: start standby timer at 419.565092
06/17/24-19:28:29 DEBUG AutoSuspend: scheduling next standby check in 1
06/17/24-19:28:29 DEBUG AutoSuspend: preventStandby

Sometimes it doesn't, so net benefit is still positive I think.