Comme=
nt # 31
on bug 10264=
6
from Timothy Pearson
(In reply to L.Y. Sim from comment #30)
> I have this issue on a 3840x1600 Acer XR382CQK w=
ith an RX560 with Kernel
> 4.18.5-1 on Manjaro.=20
>=20
> When I set the refresh rate to 75Hz, severe artifacts and flickering a=
ppear.
>=20
> Both=20
>=20
> echo high > /sys/class/drm/card0/device/power_dpm_force_perform=
ance_level
> and
>=20
> echo low > /sys/class/drm/card0/device/power_dpm_force_performa=
nce_level
>=20
> stop the flickering and artifacting, and I can see via=20
>=20
> cat /sys/class/drm/card0/device/pp_dpm_mclk=20
>=20
> that the memory clocks are set to 1750Mhz and 300Mhz respectively.=20
>=20
> However, if /sys/class/drm/card0/device/power_dpm_force_performance_le=
vel is
> set to auto, I can see (via watching /sys/class/drm/card0/device/pp_dp=
m_mclk
> with time intervals around 0.1s), that the memory clock oscillates rap=
idly
> between 300Mhz, 625Mhz and 1750Mhz.
>=20
> So it seems to me that the rapid change in memory frequency is what's
> causing the flickering.
Confirmed here on a Polaris 10 GPU (WX7100) on DisplayPort with the latest
kernel master from GIT (4.19+). The workaround sequence above stops the
irritating flickering. dc=3D0 alone does /not/ stop the flickering, and dc=
=3D1
yields no displays detected due to some other bug.