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For me it works until I first hibernate the computer. Then it stops working until a full reboot. (However sometimes it works also after hibernation.)
I found the following workaround:Download the Intel HD Graphics driver for your ThinkPad model from the Lenovo website and install it. You then have a folder C:\DRIVERS\VIDEO\Graphics.
Now, every time it stops working, go to this folder, search for the *.inf file located there (for me it was called ki120591.inf but it may be different for different models), right-click it and select "install". After a few seconds, the screen will refresh and brightness will work again for the current session.
This can also be done from a shortcut using "infdefaultinstall" and the full path to the inf file, e.g. "infdefaultinstall c:\DRIVERS\VIDEO\Graphics\ki120591.inf"
Latest, even faster, solution:
Download "devcon.exe" as described here: windows - Quick Method to install DevCon.exe? - Super User
Then, from an elevated command prompt, run "devcon listclass display" to identify the device ID of the video card. It will start with PCI\VEN_8086&. Now, to fix the brightness when it is stuck, run - again from an elevated command prompt (otherwise you will get a misleading error that no matching devices were found): devcon restart "@PCI_VEN8086&........." - where the thing after the @ is the device ID you copied earler.
For me, for example (not sure if it's the same at all models), the command was: devcon restart "@PCI\VEN_8086&DEV_1916&SUBSYS_223817AA&REV_07\3&33FD14CA&0&10"
This can even be automated by adding a task scheduler entry which triggers on a system event as follows:
- Log: System
- Source:Power-Troubleshooter
- Event ID: 1
Then configure it to run the command I wrote above (adjust path to devcon.exe and device ID as needed) and enable "run with highest privileges" to avoid a UAC prompt.
A simpler way may be restarting the Windows graphics stack using the key combination Win+Shift+Ctrl+B. However I can't test it right now because brightness works for me now even after hibernation, but who knows for how long.<< Nope, this simpler way doesn't work
Last edited by CherryDT; 16 Mar 2017 at 16:30.
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