Re: Psychedelic GUI after stable update to buster

["Alexander V. Makartsev" <avbetev@gmail.com>]

On 14.07.2019 12:02, hobie@rumormillnews.com wrote:

On 14.07.2019 4:20, Felix Miata wrote:

hobie@rumormillnews.com composed on 2019-07-13 18:07 (UTC-0400):

Thanks for the tip.  Looks like a lot of information here but I don't
really understand it.  Xorg seems to have unloaded the radeon
driver...?
Graphics:  Device-1: AMD Kaveri [Radeon R7 Graphics] vendor: ASUSTeK
driver: N/A
           bus ID: 00:01.0 chip ID: 1002:130f
           Display: x11 server: X.Org 1.20.4 driver: ati,vesa
           unloaded: fbdev,modesetting,radeon resolution: 1600x900~N/A
           OpenGL: renderer: llvmpipe (LLVM 7.0 128 bits) v: 3.3 Mesa
18.3.6
           compat-v: 3.1 direct render: Yes
Where would I find "AMDGPU" and how would I get Xorg to use it?

These should cover it:
apt purge xserver-xorg-video-ati xserver-xorg-video-radeon
apt install xserver-xorg-video-amdgpu firmware-amd-graphics

To install "firmware-amd-graphics" package is a good suggestion.
But chances are high that removal of *-ati and *-radeon packages will
also remove Desktop Environment, because those packages are part of
"xserver-xorg-video-all" package.
I'd suggest a less radical approach and simply "tell" the system what
driver to use via modprobe config files. [1]

Thanks. :)  I find old files in /etc/modprobe.d:

-rw-r--r-- 1 root root  154 Nov 29  2016 amd64-microcode-blacklist.conf
-rw-r--r-- 1 root root   23 Apr 28  2011 i915-kms.conf
-rw-r--r-- 1 root root  154 May 15  2017 intel-microcode-blacklist.conf
-rw-r--r-- 1 root root   51 May 10  2014 modesetting.conf
-rw-r--r-- 1 root root  292 Aug  3  2012 nvidia-kernel-common.conf
-rw-r--r-- 1 root root  119 Nov 12  2013 oss-compat.conf
-rw-r--r-- 1 root root   27 Jan 19  2014 radeon-kms.conf

...I find radeon-kms.conf contains: "options radeon modeset=-1".  Is that
likely where my problem, or part of my problem, is coming from?

Kernel mode setting (modeset) is often required to be enabled with recent kernels. "-1" usually means "auto".
"radeon-kms.conf" is not part of any package in stretch, so I assume it was manually created or a leftovers of some sort from previous system upgrades.

The safest approach to test if switching to "amdgpu" driver will help, would be adding kernel module parameters at boot time.
Press "e" to edit grub menu entry and add parameters to "linux" line after "quiet" parameter:

amdgpu.si_support=1 amdgpu.cik_support=1 radeon.si_support=0 radeon.si_support=0

and continue to boot your system by pressing F10.

If after that your issue with colors will be resolved, to make those changes permanent, I suggest you to create
a file named "amdgpu-kms.conf" in "/etc/modprobe.d/" with these contents:

options amdgpu si_support=1
options amdgpu cik_support=1

And change contents of "radeon-kms.conf" to:
options radeon modeset=1
options radeon si_support=0
options radeon cik_support=0

Next step is to update initramfs with changes you made and reboot:
$ sudo update-initramfs -u

These actions should permanently switch your default driver from "radeon" to "amdgpu" and hopefully resolve your issue with colors.
Just in case something will happen and you will end up with unresponsive black screen, create a live recovery system on USB flash drive so you can undo changes you made.

-- 
With kindest regards, Alexander.

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