On 8 December 2014 at 10:34, Theodore Ts'o tytso@mit.edu wrote:
This is an update to a problem which I reported several months ago (see below). The symptoms have changed a bit since then, but they've stablized since 3.17 and 3.18-rcX, and while annoying, it's tolerable, so I've been living with it.
What I'm basically seeing now is that any external monitor (either a Dell 30" or Dell 24") will be seen after a reboot or a restart of the X server. But if suspend the laptop, disconnect from the dock, and resume, and then later on, reconnect to the dock, the external monitors are not visible until I kill and restart the X server. Another part of the symptom is when I try to probe for the monitors, using either xrandr or xfce4-display-settings, the system freezes for a second or two, and then when it recovers, if I look in the logs, I see the following warning message, repeated twice:
I suspect a lot of the problems are just that xfce isn't sufficiently handling randr events, and it is getting out of sync, it is like hotplug networking before NetworkManager etc.
I just tried using XFCE from F21 and if I leave the display settings app open it crashes hard when I tried the cycle above, which didn't lend me much confidence, it also never reenabled the monitor when it came back,
I've tried a few cycles of this with GNOME desktop and it seems to work pretty well.
I'll try reproducing the exact problem you are seeing however,
I haven't managed that with drm-next tree which has v3.18 merged now.
The i915 driver also has a tendency to WARN_ON on pointless things, the i915 developers insist these are actual bugs, but don't insist on producing patches to fix them in a reasonable time frame or if they do, they add 5 more WARN_ONs to compensate.
Dave.