Re: Wake-on-timer rtcwake experiments on various PC hardware

Mon, Apr 17, 2023 at 04:38:11PM +0300, Marko M=E4kel=E4 wrote:
>Mon, Apr 17, 2023 at 10:17:03AM +0200, g.bruno wrote:
>>here a longer thread at problems with rtcwake (in German):
>>
>>https://forum.ubuntuusers.de/topic/rtcwake-geht-nicht-mehr/#post-9369451
>
>Thank you. I am not going to use rtcwake on those 2 problematic =

>laptops for anything real, but out of curiosity I will experiment a =

>bit more.
>
>One user wrote there that after a reboot, the wakeup time is still =

>there after reboot, but the IRQ is disabled.
>
>The "powertop" tool was not mentioned yet. A possible fix might be to =

>use it to enable power management on the offending devices.

"sudo powertop" indeed fixed the HP laptop. I pressed the TAB key 4 =

times to get to the "Tunables" screen, then used the up and down arrow =

keys and the Enter key to toggle each "Bad" to "Good". Near the top of =

the screen the corresponding command was displayed.  Finally, I pressed =

Esc and waited several seconds to exit the program. Below are a few =

examples of such tuning advice, from my desktop system:

echo auto > /sys/bus/usb/devices/3-1/power/control
echo auto > /sys/bus/pci/devices/0000:09:00.0/power/control
echo med_power_with_dipm > =

/sys/class/scsi_host/host0/link_power_management_policy

The page https://help.ubuntu.com/community/PowerManagement/ReducedPower =

mentions a tool pm-powersave and some options. That could be useful for =

making such power-saving changes permanent on startup.

On the IBM Thinkpad X60, fixing the "Bad" things to "Good" was not to =

enable the wake-up. In the BIOS setup there is a setting that can =

prohibit power-on-timer when the system is on battery power, to protect =

an old-fashioned spinning HDD from damage in case the laptop happens to =

be moving at the wakeup time. I have an SSD, so I had enabled that, and =

the system was on AC power anyway. But the system did not wake up.

After doing the "powertop", I executed the following to diagnose it:
sudo rtcwake -m no -s 300 && sudo reboot
sudo rtcwake -m show
sudo journalctl -x

The "rtcwake -m show" straight after the reboot indicated that the alarm =

is off. I read all journal entries between the two rtcwake commands, =

which were helpfully logged. The only thing I found was a kernel boot =

message that said that the RTC device supports wakeup from the ACPI S4 =

state (hibernate, suspend-to-disk). The normal "soft power off" would be =

S5. So, I will have to shrink the file system and create a swap =

partition, to enable the suspend-to-disk. I expect that after this =

exercise, "rtcwake -m disk -s 300" should actually work, perhaps even =

without using any "powertop" spells.

	Marko

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