https://bugs.freedesktop.org/show_bug.cgi?id=81382
--- Comment #37 from Christophe Migliorini mig+freedesktop@chene.vingt-et-un-cinq.fr --- Apparently only "set the default backlight level to something reasonable" patch was applied to 3.13, so I don't have the "radeon_encoder_add_backlight" function, thus this won't work at all.
Would you suggest I first apply the patch published here on 2014-09-17?