Created attachment 143754 =
[details]
dmesg output
I have a=C2=A0Radeon RX560 and VGA monitor (with broken EDID) connected via=
a=C2=A0cheap
HDMI-to-VGA converter (with its own broken EDID).
The=C2=A0system starts up normally. During boot up, it should change display
resolution as=C2=A0specified in the=C2=A0kernel command line (`video=3D1280=
x1024-32@75`,
monitor native). Screen turns black instead, and resolution remains unchang=
ed.
But after I plug HDMI out and in, the=C2=A0monitor gets new resolution and =
shows
console login prompt, as expected. (X isn=E2=80=99t configured to=C2=A0star=
t at bootup).
Then, when I `startx`, it chooses the=C2=A0same resolution but wrong freque=
ncy (85
Hz, too much for my monitor). That=E2=80=99s probably due to=C2=A0converter=
supplying the
EDID. After I run `xrandr --rate 75`, it switches to=C2=A0the=C2=A0correct =
mode.
I wouldn=E2=80=99t even mention such small nuisance, but if I specify exact=
ly the same
mode (as reported by `xrandr --verbose`) explicitly (as a=C2=A0`Modeline`),=
it works
but flickers, despite the=C2=A0`TearFree` option enabled. Moreover, when th=
e monitor
is turned off and then on, it wakes up in the same mode *but flickers.*
Changing mode back and forth (`xrandr --output HDMI-A-0 --preferred ; xrandr
--rate 75`) helps.
I usually have `compton` running. Without it, flicker is tolerable but still
present.
OS: Arch Linux
Kernel: Linux 5.0.1-arch1-1-ARCH
X driver: xf86-video-amdgpu 19.0.0-1