I have a laptop with a Mobility Radeon HD3470 (RV610) and Plasma 5.6.2 as desktop environment. After suspending to RAM and resuming, I experience a system freeze when trying to switch to a dual monitor setup using an external monitor connected to the VGA output. The dual monitor can be turned on without problems before the suspend/resume cycle. I don't know which logs/information could be useful to diagnose the problem, so I will provide it on demand. Thanks. System details -------------- VGA: Mobility Radeon HD3470 (RV610) OS: ArchLinux 64 bit, kernel 4.4.7, xf86-video-ati 7.7.0 Desktop: Plasma 5.6.2 (with KF5 5.21 and Qt 5.6.0) Steps to reproduce ------------------ - Start the system with only the laptop panel turned on - Suspend to RAM and then resume - Connect an external monitor - Enable the external monitor with xrandr or with the KCM module (System settings -> Display and Monitor -> Display configuration)
Please attach your xorg log and dmesg output. Does the whole system freeze or just X?
Created attachment 122958 [details] dmesg
Created attachment 122959 [details] Xorg.0.log
The freeze is only related to X, I guess. If, after triggering it, I'm quick enough to switch to a tty then the system is still responsive, I can log in and input commands to the shell (this is how I got the dmesg after the freeze). If instead I wait a bit after the freeze then the keyboard and the mouse become unresponsive, and pressing Ctrl+Alt+F2 has no effect. The system gets stuck with a black screen, the mouse cursor can still be moved around but clicks have no effect. The same happens when switching back to X from the tty after the "quick switch to tty" mentioned above.
The X desktop size changes from 1280x800 to 3200x1080 around the time the GPU hangs. Can you also reproduce the problem by only changing the desktop size, without changing anything about the external monitor, e.g. using something like xrandr --fb 3200x1080 ?
Changing the desktop size screws the screen but the system is still responsive. I can go back to a fully working situation with xrandr --fb 1280x800 I attach the relevant parts of dmesg and Xorg.0.log.
Created attachment 122961 [details] dmesg on screen resize
Created attachment 122962 [details] Xorg.0.log for screen resize
Does disabling dpm fix the issue? remove radeon.dpm=1 from your kernel command line in grub. dpm is disabled by default on r6xx due to stability issues.
Yes, disabling dpm the problem vanishes.
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