This is a small application to manually control the fan speeds for ThinkPad laptops running Linux. It's very much modeled on this project: Stanko/ThinkPad-Fan-Control, in particular This fork, which expanded on the original.

That repo is getting on a bit, however, and still relies on GTK2. I've essentially copied the UI roughly (that is to say: I eyeballed it), and added some small tweaks that I thought made sense, namely:

• Scan intervals being used to report the temperature in real time (including when in manual control).
• A dialog prompting to set the fan speed to AUTO when exiting the application.
• The ability to specify a scan interval for manual control that is different to the one for auto control.
• in terms of code: I removed a bunch of global variables, in favour of the gpointer argument passed to the signal handlers.

There are, of course a lot of things that can do with some improvements:

• Improve the Makefile
• Replace the application type to a composite passing only the parts that actually make sense to the various callbacks.
• Add the ability to set fan speeds for various temperature points (e.g. 30-50: speed 1, 51-60: speed 4, 61-70: speed 7, 71+; speed FULL).

All you really need is gcc, pkg-config, make, and have gtk+-3 installed. If you don't have make, as you can see in the Makefile, the only thing that is needed to compile this is:

$ gcc -O2 -Wall -o build/fan_control src/main.c `pkg-config gtk+-3.0 --libs --cflags`

The UI, as mentioned, was slapped together quickly, and intended to look like the original project as much as possible. It's a bit janky ATM, though. The code is not too messy, but much like the UI, was written pretty much on the fly. It could be improved upon. As it stands, the project is working just fine on my T480, and I'm running it as I'm typing this readme. It does what it was intended to do, but I'm treating it as a hobby project for when I have some spare time for tinkering.

Something that has been bugging me is that currently there is no support for config files to change the defaults (other than editing the glade file). I'd quite like to pull those values in from a more user-friendly formatted file. Once fan control is active, the way to switch it off currently is to switch to the Manual tab and set the fan speed to AUTO. This again is not very user-friendly. When operating in curve or auto modes, the Apply button should be updated and set the fan control back to AUTO.

On startup, you'll see the following screen, where you can specify a critical temperature, the fan speed to be applied when the CPU temp exceeds the critical temperature threshold, and a safe temperature at which point the fan gets reset to AUTO levels (ie the default profile). You can set a scan interval (in seconds) for how often you want the CPU temps to be checked.

The Manual Control tab allows you to forcefully set an immutable fan speed. There is a scan interval input here, too. This is used to specify how often you want to check the CPU temperature. The current CPU temp, fan speed, and time will be constantly updated as shown here:

The Curve control tab is where you can set a low/safe temperature and a fan speed (e.g. 35 degrees, fans to 1 or AUTO), and a critical temperature and a fan speed (recommended FULL SPEED). The fan speed in between is controlled by the temperature delta and fan speed increments. The practical upshot of this mode is that it allows you to create a fan curve, albeit a linear one. An example of a configured curve could be:

| Safe temperature     | 35 | Safe Fan Speed      | 1          |
| Temperature Delta    | 5  | Fan speed increment | 1          |
| Critical temperature | 65 | Critical Fan speed  | Full-Speed |
| Scan Interval        | 5  | Decrement Threshold | *- 50 -*   |

Configured in the app like so:

This will check the CPU temperature every 5 seconds, if the temperature is below 40 degrees (the safe temperature + delta -1), the fans speed will remain at 1. For every 5 degrees the CPU temperature is higher, the fan speed will be increased by 1 step (1-8, where 8 is full speed), until the CPU hits 65 degrees or more, at which point the fans will be set to full-speed. To this I added a Decrement threshold slider. This is a percentage of the temperature delta that the CPU temperature has to drop below before turning the fans down. For example: at 60 degrees, the fan speed is increased to 7. With Decrement Threshold set to 50, the fan speed won't drop back down to 6 until the CPU temp reaches 57.5 degrees (truncated because ints -> 57 degrees). This threshold is adiseable to avoid continuous ramp-up/ramp-down noise (fan speed too low at 59 degrees -> CPU heats up to 60 -> fan speed increases, cools CPU down to 59 -> CPU heats up, increases fan speed -> ...). Frequently changing fan speeds, though the noise is the same in both cases, just makes the fans more noticeable, so I added this as a quality of life thing.

Overall, the fan curve would still look something like this (fan speed in function of temperature):

Just a simple about tab, using the logo of the original project, crediting the people who originally created the (GTK+-2.x) version of this utility.

When exiting the application, if the application has set the fan speed to anything other than AUTO, a dialog will appear asking whether or not you want to set the fan speed back to AUTO before exiting. Choosing Cancel will close the dialog, and the application will stay open.