This might be fixed in the upstream 3.12.5 kernel by this commit (the model name in the patch description is mispelt, but I've checked the patch's source code and it is spelt correctly there, which is what matters):
commit 97b054c2ee8ba8a3542f391641fd78f6e3e44f0a
Author: Alan Cox
Date: Tue Dec 3 13:56:56 2013 -0800
This might be fixed in the upstream 3.12.5 kernel by this commit (the model name in the patch description is mispelt, but I've checked the patch's source code and it is spelt correctly there, which is what matters):
commit 97b054c2ee8ba8a 3542f391641fd78 f6e3e44f0a
Author: Alan Cox
Date: Tue Dec 3 13:56:56 2013 -0800
drivers/ char/i8k. c: add Dell XPLS L421X
commit 9aa5b0181bdf335 f0b731d8502e128 a862884bcd upstream.
Addresses https:/ /bugzilla. kernel. org/show_ bug.cgi? id=60772
Signed-off-by: Alan Cox
Reported-by: Leho Kraav
Signed-off-by: Andrew Morton
Signed-off-by: Greg Kroah-Hartman