Brightness controls not working on an HP DV7-6135dx

Question

below is the list of some of my laptop's hardware thru #lspci:

00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09)

00:01.0 PCI bridge: Intel Corporation 2nd Generation Core Processor Family PCI Express Root Port (rev 09)

00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09)

00:16.0 Communication controller: Intel Corporation 6 Series Chipset Family MEI Controller #1 (rev 04)

00:1a.0 USB Controller: Intel Corporation 6 Series Chipset Family USB Enhanced Host Controller #2 (rev 05)

00:1b.0 Audio device: Intel Corporation 6 Series Chipset Family High Definition Audio Controller (rev 05)

00:1c.0 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 1 (rev b5)

00:1c.1 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 2 (rev b5)

00:1c.2 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 3 (rev b5)

00:1c.3 PCI bridge: Intel Corporation 6 Series Chipset Family PCI Express Root Port 4 (rev b5)

00:1d.0 USB Controller: Intel Corporation 6 Series Chipset Family USB Enhanced Host Controller #1 (rev 05)

00:1f.0 ISA bridge: Intel Corporation HM65 Express Chipset Family LPC Controller (rev 05)

00:1f.2 SATA controller: Intel Corporation 6 Series Chipset Family 6 port SATA AHCI Controller (rev 05)

00:1f.3 SMBus: Intel Corporation 6 Series Chipset Family SMBus Controller (rev 05)

01:00.0 VGA compatible controller: ATI Technologies Inc NI Seymour [AMD Radeon HD 6470M] (rev ff)

07:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 06)

0d:00.0 Network controller: Intel Corporation Centrino Wireless-N + WiMAX 6150 (rev 67)

13:00.0 Unassigned class [ff00]: Realtek Semiconductor Co., Ltd. Device 5209 (rev 01)

19:00.0 USB Controller: NEC Corporation uPD720200 USB 3.0 Host Controller (rev 04)

Any ideas how to fix the problem permanently? So I can finally migrate to the latest version.