Comment 25 for bug 1791312

my laptop: HP Compaq nx9420
my grafic card:
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] RV530/M56-P [Mobility Radeon X1600] (prog-if 00 [VGA controller])
screen resolution: 1680x1050@60.1

when booting UBUNTU "14.04.5 LTS, Trusty Tahr" kernel 3.13.0-160-generic
-> the screen is fine in text-mode and in grafic-mode; NO flickering.
boot-messages say:
[drm] Initialized radeon 2.36.0 ...

BUT,
when booting UBUNTU "18.04.1 LTS (Bionic Beaver)" kernel 4.15.0-36-generic
-> the screen starts heavy flickering as soon as the kernel-module "radeon.ko"
is loaded. The flickering continues in grafic-mode.
here the boot-messages say:
[drm] Initialized radeon 2.50.0 ...
so: this seems to be a new version of radeon.ko.

My question:
- is there a method or a 'hidden flag' to switch radeon.ko-2.50 back to the
  good behaviour of radeon.ko-2.16?