Created attachment 140366 [details]
Symptom: flicker or tearing (not sure what to call it) at the bottom of the screen as seen in this videos:
Fedora 28 (old install): https://www.youtube.com/watch?v=q9tHH2LdYOc
Ubuntu 18.04 (currently installed, with glxgears info in description): https://youtu.be/CsFHt74HY3A
Tested on: Debian Jessie KDE, Kubuntu 18.04, Fedora 28, Elementary OS Loki, Ubuntu 18.04, all exact same symptom.
Hardware: Macbook Pro 11.5
description: VGA compatible controller
product: Venus XT [Radeon HD 8870M / R9 M270X/M370X]
vendor: Advanced Micro Devices, Inc. [AMD/ATI]
physical id: 0
bus info: pci@0000:01:00.0
width: 64 bits
capabilities: pm pciexpress msi vga_controller bus_master cap_list rom
configuration: driver=radeon latency=0
resources: irq:51 memory:80000000-8fffffff memory:b0c00000-b0c3ffff ioport:3000(size=256) memory:b0c40000-b0c5ffff
Added TearFree, DRI3 and glamor to try to remedy the symptom, nothing changed:
Option "TearFree" "on"
Option "DRI" "3"
Option "AccelMethod" "glamor"
Xorg log attached. Some device busy errors seen at the bottom, not sure if it has any relation.
Nothing really interesting in dmesg.
Symptop appears even at single monitor, however, my current setup is triple external plus native hidpi:
xrandr --fbmm 11520x4200 --output eDP --pos 4320x2400 --mode 2880x1800 --scale 1x1 --primary --output DisplayPort-1 --pos 0x0 --mode 1920x1200 --scale 2x2 --output DisplayPort-0 --pos 3840x0 --mode 1920x1200 --scale 2x2 --output HDMI-0 --pos 7680x0 --mode 1920x1200 --scale 2x2
Please attach the corresponding dmesg output as well.
Created attachment 140367 [details]
From the Xorg log file:
[ 158.424] (WW) RADEON(0): flip queue failed: Device or resource busy
[ 158.424] (WW) RADEON(0): Page flip failed: Device or resource busy
[ 158.424] (EE) RADEON(0): present flip failed
This looks like a page flip is attempted while another one is still pending. Unfortunately, handling that better turns out to be a surprisingly tricky problem, but I think the best place would be xserver/present/present_scmd.c, delaying the page flip until the previous one has completed.
Meanwhile, if you can try a GNOME on Wayland session, that might work better.
Wayland seems to resolve this issue. Unfortunately I probably won't be able to use it since there is no xrandr on Wayland so I can't also have my uber monitor setup with correct per-monitor scaling.
(In reply to cen.is.imba from comment #4)
> Unfortunately I probably won't be able to use it since there is no xrandr on Wayland
Right, you have to configure the display layout in the corresponding desktop environment settings.
> so I can't also have my uber monitor setup with correct per-monitor scaling.
Actually, Wayland is superior to Xorg when it comes to per-monitor scaling as well. It may depend on the specific (version of) Wayland compositor you're using though.
Yeah in theory it should "just work". In reality when setting to default scaling my HiDPI is still tiny and externals are normal. When setting to 200% scaling, externals are huge. Even if I get this default to work it still doesn't work for xwayland apps which are plenty. KWin seems to be better about this (so I read).
Also, gnome Display settings does not persist across reboots (I have to rearrange monitors on every boot, annoying as hell). Which was one of the reasons I had to use xrandr script in the first place.
This of course has nothing to do with this bug so I will either live with the flicker for now or deep dive into Wayland and try getting it to work somehow.
Looks like I spoke too soon. After another reboot into wayland session it is now also flickering on wayland.
Created attachment 140421 [details]
Journalctl when running a Wayland session, might be relavant (or not)
Booted into Mac OS, same issue appears. I think this might actually be hardware problem and has nothing to do with the drivers.
That's too bad, but thanks for the follow-up, resolving accordingly.