SDDM issue on 15.10 after recent kernel upgrades

[sweasyf]

After a reboot, I now get a munged screen - it looks like the size/refresh or something is terribly wrong. I can see colors of the desktop but the desktop is unintelligible. I have been able to get to a working system by dropping to a terminal ALT-F2 (I see a few pixels shift so I think I'm in a terminal) Type in sudo systemctl enable sddm.service -f ENTER then the sudo password.

The system will then log me in - the screen is still munged, but I have simple slate gray background and can see it change from the default orange stuff. once the disk stops working I again ALT-F2, type logout and get dropped to sddm where I can now magically see everything just as it should be. I wonder if I might have some issues with files in ~/.local or ~/.kde but why would a kernel update cause an issue there. Weird.

x86_64 Linux 4.2.0-27-generic
AMD A6-3620 APU with Radeon HD Graphics @ 2.2GHz

[sweasyf]

a quick note: I am seeing lots of errors like this
kernel: [ 182.229964] usb 4-2: 1:1: cannot get freq at ep 0x1
in /var/log/kern.log.

[oshunluvr]

That error is from a USB device. Not likely the source of your problem, which I would guess is related to video driver.

[sweasyf]

This is the problem I am having
https://bugs.launchpad.net/kubuntu-ppa/+bug/1535763

@oshunluvr, you are correct, I have a usb soundcard that is apparently having issues communicating since the system has already mounted the internal sound card at that point. I can fix that by removing the internal card since I'm not using it.

The SDDM problem is evil though.

[oshunluvr]

Does restarting SDDM clear it up, like reported in the bug? It looks like you have to either;

1. Revert to the previous version of SDDM
2. Replace SDDM with another DM. lightDM was Kubuntu's previous DM and it's in the repos still. KDM is not.
3. Write a short script to automatically re-launch SDDM after log in - not the best solution, but should do the trick. Then you need only wait for an update to fix your problem and then remove the script.

[sweasyf]

I had to ppa-purge backports to get this fixed. Not really the right answer, but the only one I could figure out.
5.5.3 just didn't hack it on the HP-desktop, 5.4.2 is ok.
5.5.3 shows none of these issues on a Dell Inspirion laptop I have it on, strange.

[LinkBot]

There could be problems with certain X/GPU/sddm theme combinations: Bug 358171 - Breeze theme breaks sddm - login screen presented three times - https://bugs.kde.org/show_bug.cgi?id=358171