Keyboard backlight Lenovo Laptops

[herralexanderru-byte]

Hey Hexawyz,

I´m a complete newbie to modifiying my device, but I´m trying to enable granular control for the brightness of my keyboard backlight on my Lenovo Yoga Slim 7 14ILL10.
Unfortunately the built in device manager Lenovo Vantage only provides the Options bright and dim, which is still very bright, but granular control should be possible given the smooth rise of brightness upon device boot.
I´m aware that there is scripts availiable for thinkpads, and I´m sure other yoga users are unhappy with their overly bright backlight. Unfortunately I don´t have the necessary skills to make something myself atm. Really hoping I´m in the right place, first time I write on Github.

Kind regards
Alex

[hexawyz]

Hello

Sorry for the late reply, I totally missed this 😅

So, we have two main problems here:
First is that I haven't yet implemented a way to manually adjust backlight brightness on any keyboard yet (i.e. the UI and backend are missing), so this would be required to provide the feature you want.
Second, which is the more complex one, is that I can't do much for a device that I don't own.

Given that this is a laptop, I would assume that the keyboard is connected through a low level protocol such as SPI or SMBus, which may make it hard to find our how to communicate with it.

The first thing you will absolutely want to know is how to communicate with the device.
There are a few possible scenarios there, not all of which are mutually exclusive:

• USB HID: This is the easiest one and you can use Wireshark with usbpcap installed to get traces (need to filter on the correct device as there is often a lot of noise)
• USB Other: Can still be be investigated with Wireshark, but unless the driver is WinUsb, it will require a custom driver
• SMBus: It will be more difficult to investigate, but we should be able to communicate with these devices if we know how they work
• SPI: I have no idea how to work with this 🤷‍♂️
• ACPI WMI: Some devices are exposed to the OS (Windows/Linux) by the ACPI BIOS through WMI. This will be specific to your manufacturer/motherboard/keyboard, but if it is the case, it is a matter of finding the correct WMI class. (It may not be the most efficient way to access any device, but it is at least somewhat easy when possible)
  You will have to play with WMI (or CIM) commands in Administrator PowerShell to find out. It may take some time, but if there is something you will find it.
  You can list WMI classes as follow: Get-CimClass -Namespace root/wmi (for the legacy WMI namespace, more likely) and Get-CimClass -Namespace root/cimv2
• WMI: It is also possible that your device is exposed in some kind of standard way (e.g. temperature sensors) through WMI and Windows will have it mapped there in one of the standard classes. Doubtful in the case of keyboard backlight, but the search will be similar to the above one (except that you will have to look for the standard classes / instances)
• Vendor specific driver: This one is not actually as bad as it may sound. If the device is managed by a very specific driver, it is possible to just understand how to talk with the driver (using ioctls) and bypass the software entirely. The driver will still be required to be installed.
  You can find the list of drivers installed on your machine through Windows Device Manager.
  The most obvious way is to find your device in the tree and look at what drivers are used for it. (There may be multiple logical "devices" for your one physical device)
  Switching views to the device container view can also be useful if your device is not attached to the root container (which is often the case for OEM devices)
  The less obvious way is to use the driver view and look at all the drivers installed on your computer, then look at the name and take guesses, and look up on internet. Some drivers are not directly bound to a/their device, and are accessed directly through a special name (e.g. \\.\MySuperDriver) and you can only find them out in this way.

Another thing you can do is to look at the librairies and drivers bundled within the application you use to manage the device. You may well directly find a driver there, or find some library that will give some useful information.

Do note though, that while it does happen that hardware has more capabilities than exposed by software, it is not a guarantee. It may well be that the settings that are exposed in Lenovo Vantage are really the only two possible settings.

In any case, I encourage you to dig in a bit more on how the keyboard is working on your computer, as you are the only one able to get valuable information 🙂