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flatmoll

Member

Registered: 2024-12-01

Posts: 32

[SOLVED] Lenovo Yoga 14AHP9 charge threshold

Greetings! The wiki page states that charge threshold is *supported*. On TLP website, I followed the instuction for 'Other Lenovo' laptops, and got the following:

$ sudo tlp-stat -b 
--- TLP 1.7.0 --------------------------------------------

+++ Battery Care
Plugin: lenovo
Supported features: charge threshold
Driver usage:
* vendor (ideapad_laptop) = active (charge threshold)
Parameter value range:
* STOP_CHARGE_THRESH_BAT0: 0(off), 1(on) -- battery conservation mode

/sys/bus/platform/drivers/ideapad_acpi/VPC2004:00/conservation_mode = 1 (on)

+++ Battery Status: BAT0
/sys/class/power_supply/BAT0/manufacturer                   = Celxpert
/sys/class/power_supply/BAT0/model_name                     = L22C4PA1
/sys/class/power_supply/BAT0/cycle_count                    =      2
/sys/class/power_supply/BAT0/energy_full_design             =  71000 [mWh]
/sys/class/power_supply/BAT0/energy_full                    =  72420 [mWh]
/sys/class/power_supply/BAT0/energy_now                     =  24230 [mWh]
/sys/class/power_supply/BAT0/power_now                      =   2912 [mW]
/sys/class/power_supply/BAT0/status                         = Discharging

Charge                                                      =   33.5 [%]
Capacity                                                    =  102.0 [%]

Meanwhile threshold didn't work, even after several reboots. (Battery is low because I am writing this post factum).

Then I found this page, made sure ideapad_laptop is loaded and did echo - no effect. Following the link in the 'Note:' box, I installed acpi and acpi_call and echoed the solution as root. I checked the value and got:

# echo '\_SB.PCI0.LPCB.EC0.VPC0.SBMC 0' >/proc/acpi/call
# cat /proc/acpi/call
Error: AE_NOT_FOUND

Moreover, searching for 'acpi_call' in journalctl -b (https://0x0.st/8oXF.txt):

Jan 13 15:25:10 f kernel: acpi_call: loading out-of-tree module taints kernel.
Jan 13 15:25:10 f kernel: acpi_call: module verification failed: signature and/or required key missing - tainting kernel

If they're somehow related. Web searching the message, people point out BIOS incompability (?). The journal is fresh and "recreated", because I didn't record anything initially, and documenting only now.

Last edited by flatmoll (2025-01-15 19:43:16)

flatmoll

Member

Registered: 2024-12-01

Posts: 32

Re: [SOLVED] Lenovo Yoga 14AHP9 charge threshold

Update:
I've noticed that usual charge threshold files aren't present in the BAT0 folder.
Alongside I tried to create (touch/echo/tee) them, but got 'Permission denied' even as root.

$ ls /sys/class/power_supply/BAT0/
alarm           energy_full_design  power_now      type
capacity        energy_now          present        uevent
capacity_level  hwmon2              serial_number  voltage_min_design
cycle_count     manufacturer        status         voltage_now
device          model_name          subsystem
energy_full     power               technology

Either TLP fails to set thresholds, or there is a different way for this laptop.

Last edited by flatmoll (2025-01-15 18:48:11)

flatmoll

Member

Registered: 2024-12-01

Posts: 32

Re: [SOLVED] Lenovo Yoga 14AHP9 charge threshold

Solution:
Disregard the instructions I followed.
The only supported thresholds are 80 for stop and 75 for start; simply put them in TLP configuration.
No need to create anything in /sys/class/power_supply/BAT0/, and no need in acpi and acpi_call.

Last edited by flatmoll (2025-01-15 19:44:09)

tactless500

Member

Registered: 2025-01-15

Posts: 4

Re: [SOLVED] Lenovo Yoga 14AHP9 charge threshold

This is interesting behaviour, can you tell us how you figured it out? Do the charge limit entries appear under /sys/class/... after you set those 75/80 thresholds?

flatmoll

Member

Registered: 2024-12-01

Posts: 32

Re: [SOLVED] Lenovo Yoga 14AHP9 charge threshold

This is interesting behaviour, can you tell us how you figured it out? Do the charge limit entries appear under /sys/class/... after you set those 75/80 thresholds?

No, they didn't appear - I guess the ideapad_laptop module manages it in some other way (the way firmware supports it).
I was setting values between 50 and 80, incrementing by 10 and charging by little, trying to bypass each limit, until is capped at 79%.
It may be the case that once enabled, charge threshold will always be at 80% regardless of the value in TLP config.

Last edited by flatmoll (2025-01-15 20:40:52)