Bug#943585: kwin-x11: kwin (?) causes extreme flickering and tear on login
Hi,
I've encountered similar behaviour: black/residual/flickering windows
making the desktop unusable after login. I also noticed some minor (white)
flickering in SDDM prior to login, although it was still quite usable at that
point. I'm running a mixed testing/unstable system, and am also using an
Intel display chip (Dell Latitude; only on-board, no discrete graphics chip).
I found disabling OpenGL compositing with ALT+SHIFT+F12 worked around
it at first, as did downgrading KDE+QT packages back to testing. I'm just
trying this now with unstable packages again, and running the suggestsed
'DRI_PRIME=1 kwin_x11 --replace'also seems to work - even as the new
kwin_x11 instance brings OpenGL compositing back with it.
Peace,
Brendon
On Sun, 27 Oct 2019 01:15:10 +0200 Stefan Schwarzer
<stefan.schwarzer@gmx.net> wrote:
> Package: kwin-x11
> Version: 4:5.14.5-1+b1
> Severity: important
>
> Dear Maintainer,
>
> I am following debian unstable, desktop X11/sddm/kde on a Lenovo laptop
T460p.
> The nvidia graphics on the laptop is disabled in favor of the chipset
graphics
> (Intel).
>
> After the last upgrade (which was from testing to stable on the 25th
October),
> I am experiencing a mostly unusable desktop. The login screen (sddm)
comes up
> as expected,
> but right after login I get flickering black rectangles on the screen, which
> may
> cover up to 90% of its area. Windows mostly remain black or their content
> suddenly
> becomes visible he task bar remains black and I see other residuals of the
kde
> splash
> screen where windows should be drawn or the background wallpaper be
> restored. Swithing to a VT; all seems ok, kwin, the desktop and applications
> are
> running.
>
> So far, my only clue as to what may be going on is a workaroud: if I start a
> terminal
> via keyboard shortcut and issue blindly
> DRI_PRIME=1 kwin_x11 --replace
> then afterwards things behave mostly normally (Sometimes window
contaent is
> still
> not correctly updated). I just picked this line up from older bug reports
> against kwin on the net without understanding what it does.
>
> This is the output of kwin following this command in the hope that it helps
>
> OpenGL vendor string: Intel Open Source Technology Center
> OpenGL renderer string: Mesa DRI Intel(R) HD Graphics 530
> (Skylake GT2)
> OpenGL version string: 4.5 (Core Profile) Mesa 19.2.1
> OpenGL shading language version string: 4.50
> Driver: Intel
> GPU class: Unknown
> OpenGL version: 4.5
> GLSL version: 4.50
> Mesa version: 19.2.1
> X server version: 1.20.4
> Linux kernel version: 5.3
> Requires strict binding: yes
> GLSL shaders: yes
> Texture NPOT support: yes
> Virtual Machine: no
>
>
>
> -- System Information:
> Debian Release: bullseye/sid
> APT prefers unstable
> APT policy: (990, 'unstable'), (500, 'testing'), (500, 'stable'), (1,
'experimental')
> Architecture: amd64 (x86_64)
> Foreign Architectures: i386
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