Created attachment 1334604 [details]
journalctl of affected kernel
Description of problem:
After installing kernel update to 4.13.4 and rebooting, boot is normal until KMS takes over, then the display on the LCD gets garbled in a square area (800x800) at the left of the screen. The garbled area persists during the rest of the startup and into the login screen and makes the display unusable.
Previous kernel kernel-PAE-4.12.14-300.fc26.i686 does not garble the display, although it still shows a backtrace as described in #1438258, as this is the exact same machine.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Acer Aspire One ZG5 32-bit with Fedora 26 and kernel-PAE-4.13.4-200.fc26.i686
2. Boot with updated kernel
Garbled screen in a square section when KMS takes over.
No screen corruption.
Using journalctl I have captured a dmesg output of the affected kernel. Look for the string "plane B assertion failure, should be off on pipe B but is still active".
Still present in kernel-PAE-4.13.5-200.fc26.i686
Adding external bug at freedesktop.org .
I was asked to test:
and I can confirm that the applied patches fix this bug (as well as #1438258).
I can confirm the same screen corruption issue on an HP530 laptop since upgrading from 4.12.14-300.fc26.i686 which had no problem.
Issue still present in:
4.13.8-200.fc26.i686 in repo updates and
4.13.9-200.fc26.i686 in repo updates-testing (just installed now)
It appears the patch still hasn't made it into the repos yet, so will stick with 4.12.14-300 for the time being.
Still hapenning under Fedora 27, with kernel-PAE-4.13.13-300.fc27.i686 and with the same symptoms. I am forced to keep and boot into kernel-PAE-4.12.14-300.fc26.i686 from Fedora 26 for just this reason.
Still happening under kernel-PAE-4.13.15-300.fc27.i686 .
I didn't notice before as I can only ssh in, but keyboard and trackpad are also unresponsive on all kernels, and kernel errors are issued in ssh session on screen blank and awaken.
However, an external usb keyboard works and usb mouse moves the pointer ok above the corrupted screen, but otherwise the laptop is totally unusable except via ssh.
https://bugs.freedesktop.org/show_bug.cgi?id=102929 has some more info about this bug.
Still not fixed in 4.14.3-300.fc27.i686 !
No trackpad or keyboard response, only external usb keyboard and mouse responds but screen corruption makes these unusable.
Really don't want to spend hours downgrading to fc26.
With kernel 4.15.3-300.fc27.i686 this bug has been fixed. Thanks!