Created attachment 138467 [details]
backtrace trying drm-4.17

As stated in bug 105760, drm-4.17 didn't make any difference for me, though,
setting acpi_backlight=intel_backlight, as mentioned
in(https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1656649), allowed me to
boot once without any backtraces, using an stable kernel:

$ DRI_PRIME=1 glxinfo
...
OpenGL vendor string: X.Org                                                     
OpenGL renderer string: AMD Radeon (TM) R7 M360 (ICELAND / DRM 3.23.0 /
4.15.12+, LLVM 6.0.0)                                                           
OpenGL core profile version string: 4.5 (Core Profile) Mesa 18.0.0              
OpenGL core profile shading language version string: 4.50                       
OpenGL core profile context flags: (none)                                       
OpenGL core profile profile mask: core profile
...

I'll try to reboot several times to see if the work around works always, and
let you know about it.

Thanks!

José.