Note that it’s currently hard-coded in the Kext, so if you prefer a different brightness setting, you’ll have to adjust it as necessary. I adapted it for use in NVDAGPUWakeHandler to set the backlight to a usable level after waking from sleep. You can also see that macOS no longer thinks there is any backlight control for this display:įortunately the Linux driver for the GMUX controller in the MBP contains code to support modifying the backlight setting. If you hold up a flashlight, you can see that the screen is on, but with no backlight it appears nearly black. This is sufficient to get the Mac to boot however, in High Sierra something has changed such that the screen backlight controller no longer turns on after waking from sleep. Enable backlight after waking from sleep in High Sierra (10.13) / Mojave (10.14) You can verify that SIP is disabled by running csrutil status. The MacBook boots with EFI, and hackers have found the following NVRAM parameter can be used to “prefer” the integrated GPU during startup: Modifications to only use the Integrated GPU Prefer Intel GPU on boot with NVRAM parameter It’s available on Github as NVDAGPUWakeHandler. To do this, I adapted a macOS kernel extension derived from the source code for the Linux gmux driver. This made me to hope that by forcing the NVIDIA GPU to power down I could regain use of my laptop with only the integrated GPU. This GPU is used during normal workloads to improve battery life, and the discrete NVIDIA GeForce 650M is powered down by a controller chip called the gmux. However, laptops from this period also contain an integrated GPU as part of the Intel Core i5/i7 processor. Unfortunately, the replacement period ended in 2016.

It stemms from the use of a lead-free solder that results in premature failure of the discrete graphics chips. The machine was still booting up (I could hear the chimes and the keyboard backlight worked), but no screen image or backlight whatsoever.Īfter taking it to the Apple Store, where they told me it was a Logic board failure, I learned that this is a known issue with this generation of MacBooks from 2011-2013. On Friday my laptop stopped turning on normally, leaving me stuck with a black screen.

Graphics card in macbook pro 2012