drm2 regression: backlight adjustment on ivybridge no longer works

[Andrew Wilcox]

Ranjan1018 . sent: 27 January 2015 23:42:
> The regression was introduced in r277487.

Looking closer at this revision, I believe I may see the issue.  Most of the new tunables introduced in dev/drm2/i915/i915_drv.c are uninitialised and thus probably contain junk.  It likely works for me because the firmware of my laptop 0s memory on EFI boot.

I have uploaded a diff here that I believe may fix this.  Please test and let me know:

http://foxkit.us/FreeBSD/i915-uninitialised-var-fix.diff

Best,
Andrew

--
Andrew Wilcox, C/C++/Python developer, kernel hacker
Blog:   http://blog.foxkit.us/  WWW: http://foxkit.us/
GitHub:  https://github.com/awilfox