On 4/14/25 04:33, Jonathan Dowland wrote:
On Sun Apr 13, 2025 at 10:23 PM BST, Eben King wrote:
sudo modprobe it87 force_id=0x8728
then running "sensors" shows
it8728-isa-0a40
Adapter: ISA adapter
<9 voltages>
<5 fans, one of which is 0 RPM>
<3 temps>
intrusion0: ALARM
That might be the way forward. In my case, the controller is managed by
the driver "nct6775". I have (the not-very-discoverable) sysfs
location /sys/devices/platform/nct6775.656/hwmon/hwmon2 containing files
to control things; e.g. writing 1 to ./pwmN_enable (N ∈ 1-7) sets fan
"manual control mode", after which I can write the values 0-255 to ./
pwmN to control the RPM. (I haven't got my fans to do quite what I want,
yet, but that's not the driver's fault.)
nct6775 is documented reasonably well <https://www.kernel.org/doc/html/
latest/hwmon/nct6775.html>, your controller's docs aren't quite so clear
but there's some mention of writing to pwnN_enable: <https://
docs.kernel.org/hwmon/it87.html>
Hope this helps,
Excellent, thank you. Yes as with yours if I do
sudo sh -c 'echo 1 >
/sys/devices/platform/it87.2624/hwmon/hwmon3/pwmN_enable'
where 1≤N≤3, then with
sudo sh -c 'echo X > /sys/devices/platform/it87.2624/hwmon/hwmon3/pwmN'
where 0≤X≤255 I can set the fan speed. It's approximately linear when
X≥64. If I later do
sudo sh -c 'echo 1 >
/sys/devices/platform/it87.2624/hwmon/hwmon3/pwmN_enable'
it might return the fan to automatic control, but it definitely sets it
to maximum speed. That's weird.
You are correct, those files are hidden deep within the catacombs of /sys.
