Put Fedora 20 on my Samsung RV511 yesterday, everything worked out of the box except the backlight. Using the keys or the slider moved the animation but didn’t change the brightness – which was set to nuclear eye ball toasting mode.
Both the slider and the key combinations change the values in /sys/class/samsung/backlight. I know that the ACPI BIOS can provide interfaces but not always methods to control brightness, so I added acpi_backlight=vendor to the GRUB_CMDLINE_LINUX entry in /etc/default/grub and the back-light is working fine.
Don’t forget to grub2-mkconfig -o /boot/grub2/grub.cfg.