Created attachment 375318 [details, diff] 3.4.87-fix-duplicated-key-event-in-brightness-control.patch The attached file finally fixes a long-standing problem on my Thinkpad X200s with the brightness control. Turns out all it needs is a simple (upstream) patch.
------------------------------------------------------------------------ r2789 | tomwij | 2014-05-15 20:55:59 +0200 (Thu, 15 May 2014) | 1 line Add Thinkpad ACPI backport brightness control fix; fixes bug #508146, reported by Andreas Sturmlechner. ------------------------------------------------------------------------ Will be in the next 3.4 release.