Bug 1393067

Description of problem:
I was just trying to set up dual monitors (connected via DVI to motherboard) with iGPU (Intel Core i3)
and TV connected to GPU (nVidia in PCI-E) via HDMI. System has kernel 4.8.4-200.fc24.x86_64 and
nouveau and i915 moules installed (and not blacklisted). KMS (or some) has no any modeset related parameters in grub.cfg.

So that did not work: during bootup fedora logo loader is displayed on TV while DVI
displays are blank (nevertheless signal on both of DVIs persists). Once login screen has been displayed
(on the first DVI monitor as required, so all works fine at this stage) I am trying to log in and that is faulty because
I got two blank monitors right after logging. Since now I can do nothing - TV gives me "no signal", monitors
are blank. Switching to TTY possible but it isn't very useful (in my case) as I don't know what info or logs to
search. So after reboot I edited grub2 runtime config and added nouveau.modeset=0. But I'm not
sure what is that "magic" really is for. Anyway all of the stuff proceeds correctly now. Except that
TV was not observed by OS. But I already had a clue about that so I did:
# modprobe nouveau
- that did not anything noteable as well as useful too.
so then I did:
# modprobe -r nouveau
# modprobe nouveau modeset=1

After X system (I am not sure although) was restarted the both of monitors (iGPU) and TV (PCI nVidia) work just fine.
I really didn't find any useful info about my displays setting, so I'm doing my best while trying to hanlde that
mess. Thanks!

Version-Release number of selected component:
xorg-x11-server-Xorg-1.18.4-4.fc24

Additional info:
reporter:       libreport-2.7.2
backtrace_rating: 4
cmdline:        /usr/libexec/Xorg vt2 -displayfd 3 -auth /run/user/1000/gdm/Xauthority -background none -noreset -keeptty -verbose 3
crash_function: dixRegisterPrivateKey
executable:     /usr/libexec/Xorg
global_pid:     1563
kernel:         4.8.4-200.fc24.x86_64
pkg_fingerprint: 73BD E983 81B4 6521
pkg_vendor:     Fedora Project
runlevel:       N 5
type:           CCpp
uid:            1000

Truncated backtrace:
Thread no. 1 (10 frames)
 #4 dixRegisterPrivateKey at privates.c:385
 #5 glamor_init at glamor.c:489
 #6 ScreenInit at driver.c:1225
 #7 AddGPUScreen at dispatch.c:3915
 #8 xf86platformAddDevice at xf86platformBus.c:523
 #9 NewGPUDeviceRequest at lnx_platform.c:195
 #10 device_added at udev.c:131
 #11 wakeup_handler at udev.c:357
 #12 WakeupHandler at dixutils.c:423
 #13 WaitForSomething at WaitFor.c:230

Potential duplicate: bug 1382259