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macfreek57

macrumors 6502
Original poster
Jan 1, 2002
379
0
Baton Rouge, Louisiana
Strange issue:

I've been playing around with Bootcamp to get Windows 10 running on my 2015 13" Retina MBP. I have it currently installed, drivers (including video) all appear to be working properly, however, I can't use my built-in display! As soon as I boot to Windows (shortly after the blue logo), the backlight cuts off. With the flashlight trick, I can see that the image is there, displaying full resolution, etc. The same even happens during install: blue Win logo, then blackout. Had to use an external HDMI monitor to install.

I feel like I've tried everything all with the same results:
  • messing with different drivers (Intel Iris 6100)
  • brightness/adaptive brightness/power management settings
  • safe boot
  • Windows 8
  • Ubuntu
Best guess:

It seems the problem occurs when the OS starts loading the more sophisticated video drivers. Whatever base/generic driver Windows/Linux/motherboard firmware uses to display video seems to work, but the more sophisticated video drivers flip a bit and the LED goes black. No problem in MacOS, however. I have Catalina installed and even have a small Mojave boot partition - neither have backlight issues.

My research has led me to look into the ACPI and modifying the DSDT. I feel I may be getting into dangerous territory here - I can go this route if it seems I need to, but would like confirmation from someone with more experience here. Maybe I'm chasing rabbit trails. The confusing thing is that I can't find evidence that anyone else has had this same issue.

Any ideas, guys?
 
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