Created attachment 113488 [details] journalctl -e _COMM=Xorg.bin This is on Fedora 21, with kernel 3.18.5, Xorg 1.16.3-2, Intel driver 2.99.916-3.20141117. The GPU is an Intel Corporation Atom Processor Z36xxx/Z37xxx Series Graphics & Display [8086:0f31] (rev 0c) lspci output here: https://bugzilla.kernel.org/attachment.cgi?id=165051 When connecting an external screen via VGA, and trying to set up as a clone of the internal screen via the GNOME control center, the internal screen goes blank, and only the external one is on. OTC, setting one screen as the main one, and another as the secondary one works fine. If I set up the external screen as the main one, and then set screens as clones of each other, the external screen turns blank. So it looks like it's always the main screen which turns blank. Logs do not seem to contain any error messages.
It successfully clones eDP and VGA using the same pipe... You want to attach a drm.debug=0xe dmesg.
Created attachment 113496 [details] drm.debug=0xe Here it is. Actually, I've experimented a bit more, and no consistent pattern appears wrt. cloned/main/secondary screens. It's just a mess. I noticed that after disconnecting the external monitor, I could even end up in a state where I could not get the internal screen to unblank. I had to put the laptop into suspend mode. Thus it may well be the same bug as https://bugzilla.kernel.org/show_bug.cgi?id=92241
There's also a crash that I missed (the Fedora bug reporting tool stopped showing a notification, but it's still there): https://bugzilla.redhat.com/show_bug.cgi?id=1189885
It would also be nice if you could reproduce the bug, then run "xrandr --verbose" and attach the output here, describing which screen is blank.
Created attachment 113828 [details] xrandr --verbose Here it is. I connected the VGA external screen, and it was configured as a clone of the internal one: everything was fine on both screens. Then I defined the internal screen as the primary one, and it turned blank (the external monitor was set as secondary, as could be seen from the "2" in its corner). After 60s without any reaction from my part (I couldn't see the window anymore), gnome-control-center tried to restore the configuration to its previous state (cloned screens). As a result, the internal screen remained blank, but the desktop+windows appeared on the external screen. I ran xrandr at that point.
We seem to have neglected this bug. Apologies. Does the problem persist with latest kernels and userspace?
I no longer have access to that machine and I had completely forgotten about this bug...
(In reply to Milan Bouchet-Valat from comment #7) > I no longer have access to that machine and I had completely forgotten about > this bug... Thanks for the follow-up, sorry we couldn't help you.
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