Good day!
On Sat, Feb 07, 2026 at 02:08:05AM +0100, gregor herrmann wrote:
On Fri, 06 Feb 2026 19:01:02 +0200, Dennis Yurichev
wrote:
T420 + Ubuntu 24.04.2 LTS - I could write to
/proc/acpi/ibm/fan
for fan control.
That worked.
T420 + Ubuntu 25.04 - Now I get:
====================================
% cat fan_2.sh
echo "level 2" > /proc/acpi/ibm/fan
% sudo ./fan_2.sh
./fan_2.sh: 1: echo: echo: I/O error
====================================
Known issue (after upgrading)?
Do you still have something like
# cat /etc/modprobe.d/thinkpad_acpi.conf
options thinkpad_acpi fan_control=1
Yes.
% cat /etc/modprobe.d/thinkpad_acpi.conf
options thinkpad_acpi fan_control=1
% sudo grep -i thinkpad /var/log/dmesg
BIOS vendor: LENOVO; Ver: 83ET76WW (1.46 ); Product Version:
ThinkPad
T420
[ 5.299925] kernel: thinkpad_acpi: ThinkPad ACPI Extras v0.26
[ 5.300072] kernel: thinkpad_acpi:
http://ibm-acpi.sf.net/
[ 5.300122] kernel: thinkpad_acpi: ThinkPad BIOS 83ET76WW (1.46 ), EC unknown
[ 5.300169] kernel: thinkpad_acpi: Lenovo ThinkPad T420, model 4180AH9
[ 5.317030] kernel: thinkpad_acpi: radio switch found; radios are enabled
[ 5.317139] kernel: thinkpad_acpi: This ThinkPad has standard ACPI backlight brightness
control, supported by the ACPI video driver
[ 5.317201] kernel: thinkpad_acpi: Disabling thinkpad-acpi brightness events by
default...
[ 5.354172] kernel: thinkpad_acpi: rfkill switch tpacpi_bluetooth_sw: radio is
unblocked
[ 5.355133] kernel: thinkpad_acpi: Standard ACPI backlight interface available, not
loading native one
[ 5.426089] kernel: thinkpad_acpi: battery 1 registered (start 0, stop 100, behaviours:
0x7)
[ 5.439070] kernel: ACPI: battery: new hook: ThinkPad Battery Extension
[ 5.466048] kernel: input: ThinkPad Extra Buttons as
/devices/platform/thinkpad_acpi/input/input6
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