Hello,
I am contacting the stable branch maintainers with a bug report concerning the asus-wmi kernel driver in the 4.4 kernel branch. I had initially contacted maintainers for the specific driver and received a response stating that I should contact the stable branch maintainers about the issue instead. Their opinion was that the patch in question should be reverted rather than debugged. I will append my initial report here and let you decide what to do with the bug.
Original Bug Report:
The 2019-01-26 commit to the asus-wmi.c driver code in the 4.4 kernel branch has introduced a bug with several known models of EeePC netbooks.
Description of Problem: The bug occurs during boot, where the screen (possibly backlight?) will shut off and display hotkeys are unable to bring it back on. The problem is present on all kernels since the 2019-01-26 commit. There have been several reports of the issue in the slackware forum at linuxquestions.org
Corrective actions taken so far: Appending acpi_osi=Linux will circumvent the issue and keep the screen on, but this causes several error messages in the boot log about eeepc_wmi "failing to load both WMI and and legacy ATKD devices", and warns not to use acpi_osi=Linux.
Appending acpi_backlight=vendor also prevents the screen from shutting off during boot. However, pressing the brightness hotkeys causes the system to hang.
Reversing the asus-wmi.c patch that was committed on 2019-01-26 and rebuilding the 4.4 series module also fixes the problem, and brightness hotkeys work normally. The commit in question is 0c4a25cc6f2934f3aa99a0bbfd20b71949bcad25
Model I have tested this on: ASUS EeePC 1000H (Slackware 14.2, kernels 4.4.201, 4.4.202) Additional models reporting this issue: ASUS Eee PC 1005HAB, ASUS Eee PC 1225b, ASUS Eee PC 1025c (Slackware 14.2, various kernels from 4.4.172 and higher)
Additional Notes: This problem seems to have been corrected in the 4.19 kernel branch, as reported by several users in the slackware forum. I attempted to test some of the fixes from the 4.19 code as patches to the 4.4 code but had no success. There have been multiple changes in that branch and I am unsure what exactly has corrected the bug in that version.
If there is any additional information that I can provide, please let me know.
Regards,
Bob Funk