I found the commit 80183a4b
"compal-laptop/fujitsu-laptop/msi-laptop: make dmi_check_cb to return 1 instead of 0"
has wrong patch merge.
The original patch change the return value for dmi_check_cb():
https://lkml.org/lkml/2010/7/2/88
But commit 80183a4b changed the return value for set_backlight_level.
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>
0e4510f7c9