Hide Forgot
Description of problem: Until a few days ago, I was able to use 3 displays on a Fedora 24: 1. the ThinkPad T460s laptop's built-in LCD display (1920x1080 16:9); 2. external 4k 3840x2160 (16:9), on HDMI; 3. external 1920x1080, on DP or VGA. The 3. is plugged into a Docking, no choice as the T460s laptop has no VGA or DP and I don't have a mini-DP adapter (the laptop has 1 HDMI and 1 mini DP port); the 2. either directly into laptop or docking (makes no difference). Some very recent change in a Fedora 24 package appears to have broken this for me; I'm now only able to use EITHER the 2. or the 3. but never both together anymore. It was NOT a Kernel upgrade, as I'm on todays's latest 4.6.6 but even going back to 4.6.5 and 4.6.4 it still doesn't make it work anymore. How reproducible: Plug in both external monitors. The GNOME Displays will only show either the second or the third, and the 2. will get disabled on plugging in the 3. On the bright side, and to be positive, someone did recently fix something somewhere which made it not freeze anymore all the time when plugging monitors in and out and docking and undocking, so thanks for that! ;-) Additional info: Let me know if you need me to run some command to get more system / monitor details.
PS: I did briefly try to boot the desktop into Wayland instead of X11 and the problem is the same there.
Oups... ThinkPad T460s docking station has two DP ports; simple need to use the DP #2 if HDMI is plugged in near DP #1 and 2 ext. monitors work great with both Kernels 4.6.6 and 4.6.7 (no more crashes) - SORRY!