[ltp] Thinkpad keyboard backlight ACPI interface

Bjørn Mork linux-thinkpad@linux-thinkpad.org
Tue, 28 Jul 2015 13:17:58 +0200

Pali Rohár <pali.rohar@gmail.com> writes:

> I would like to write kernel patch for thinkpad_acpi.c to support 
> keyboard backlight (like other modules in drivers/platform/x86/ tree), 
> but last missing information is how to detect current level of 
> brightness and check if backlight is supported...

Based on the code you posted, I would assume that MLCG returns the
current brightness level.  Did you test that?

The thinkpad_acpi driver use code like this to test for supported

      tp_features.bluetooth = hkey_handle && acpi_evalf(hkey_handle, &status, "GBDC", "qd");

You could do something similar for the keyboard backlight feature,
couldn't you?