Created attachment 139531 [details] Xorg log Hi, I first noticed this little bug a few months ago on my old Ivybridge laptop, then saw it again today on my Kabylake laptop. Due to heavy flickering in Chrome with SNA I still like to use UXA (this bug doesn't happen with SNA or modesetting). Unblanking the screen shows a visible cursor but a black screen unless I do a VT switch, then the unlock window to enter credentials appears. This seems to be present on the old Gnome and graphics stack from Debian Jessie as well as an up-to-date Debian Sid. This doesn't happen when resuming from suspend. I have the latest xf86-video-intel from git with debugging enabled if anyone wants to poke at this. I attached Xorg.0.log and dmesg; some of the noise earlier is me testing suspend. The main way to test is just to go to Power in settings and set "Blank screen" to 1 minute. Further complicating things is that if you do "xset dpms force off" this issue doesn't happen either, making me think screen locking is involved. Thanks! Tod
Created attachment 139532 [details] dmesg log
Note that the flickering is likely to be a kernel bug. A video of the flickering, if possible, is the easiest way to identify the likely cause. Unblanking the screen sounds like it is a stale Present buffer.
This issue doesn't happen with Wayland either. Sorry if my terminology is wrong, I should also clarify: it also unblanks in the sense that the backlight is on and the cursor is visible, but everything else is just black. I can try to get a video of the flickering. Let me confirm it's still happening on SNA in my HTML5 game, there was an oldish/heavily commented bug on here about bad interaction between Gnome compositor and SNA that I can no longer find. One moment!
Created attachment 139533 [details] screen flickering with SNA and DRI2 This is with SNA and DRI2 on Xorg. It gets progressively worse. Also, it's not visible in the video, but a white line appears above Gnome's top bar. I can't say if it will never happen with SNA/DRI3 but it didn't happen within a few minutes.
Also the flickering doesn't happen on SNA/DRI2/Wayland.
This report quickly devolved into two separate issues and I've stopped using Gnome and its compositor so can't follow up on either problem mentioned here. To my surprise Compton is working alright nowadays, at least with xrender.
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