After a longer period of DPMS (haven't tested exactly where the threshold is) I can no longer wake my external monitor. The monitor is connected with a HDMI-DVI cable directly to the HDMI port of my Dell XPS 15 9550. The monitor, a HP LA2405x, has a number of settings for source/auto-detect but none of them help. Tested with kernel 4.9.3, both with Xorg and Wayland. I see the same problem here: http://askubuntu.com/questions/699649/15-10-dell-xps-15-9550-external-monitor-not-waking and here: http://en.community.dell.com/support-forums/laptop/f/3519/t/19679539 Note this is with DPMS, doing a full suspend-resume usually fixes the problem. Another workaround is to unplug the cable and put it back.
I don't think this is a dupe of #97211 because there suspend-resume causes the problem. #99114 is a bit similar but I'd say VGA+docking station is quite different.
Ernst Sjöstrand, can you reproduce issue with "drm.debug=0xe log_buf_len=4M" in your boot command line and then attached your dmesg. Thanks
Created attachment 129104 [details] dmesg with debug log The problem occurs at the end. I lock the screen and let the monitor blank. After a few more seconds the monitor will go into it's power saving mode. (If I move the mouse now the monitor will wake up again.) After waiting a few minutes I move my mouse, nothing happens. Then I unplug the HDMI cable and plug it back in, monitor wakes up. The laptop lid is closed the whole time, AC adapter connected.
Clint, can you take a look at the log info?
Notes from dmesg dump: eDP panel is 3840x2160 PSR HDMI port is connected to DVI monitor at 1920x1200 device resumed at TS 77.50 user space segment fault: [ 80.030487] update-notifier[3767]: segfault at 0 ip (null) sp 00007ffe73e92c18 error 14 in update-notifier[5597c9d2a000+d000] HDMI adapter on HDMI-A-1 detected and enabled. device resumed at TS 207.107 HDMI adapter detected but NOT enabled No errors from TS 207-248 but drm:intel_modeset_pipe_config wasn't invoked? device resumed at TS 323.075 HDMI adapter on HDMI-A-1 detected and enabled. HDMI HPD loss received at TS 353.690 eDP enable at 3840x2160@60 HDMI-A-1 detected and enabled. End notes There does appear to be a failure to output a signal from TS 207 until 323. There are no error conditions in the dmesg log that would help point out what went wrong. It almost looks like the user space never called modeset upon resume.
Hmm, I can see if it happens with another desktop environment. Only tried with Gnome 3.
Ok I could not reproduce this with another desktop, there's something in my gnome setup. Sorry to bother you!
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