LinuxQuestions.org - [SOLVED] Ubuntu brightness can't be changed after upgrading to 13.04

Hello,
Today I upgrade my ubuntu to version 13.04 from 12.10, however , the brightness can't be adapted. I have tried the previous kernel which worked on version 12.10, brightness can't be changed too. My PC is Acer 4750G.

My boot parameter:

Code:

    RAMDISK$ cat /proc/cmdline

    BOOT_IMAGE=/boot/vmlinuz-3.8.0-29-generic root=UUID=0f905c49-affc-49b5-809b-4f7eea7dddbf ro quiet splash acpi_backlight=vendor vt.handoff=7

My graphic card details:

Code:

RAMDISK$ sudo lspci -vnn | grep -A12 VGA

    00:02.0 VGA compatible controller [0300]: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller [8086:0116] (rev 09) (prog-if 00 [VGA controller])

            Subsystem: Acer Incorporated [ALI] Device [1025:0507]

            Flags: bus master, fast devsel, latency 0, IRQ 43

            Memory at f3400000 (64-bit, non-prefetchable) [size=4M]

            Memory at d0000000 (64-bit, prefetchable) [size=256M]

            I/O ports at 3000 [size=64]

            Expansion ROM at <unassigned> [disabled]

            Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-

            Capabilities: [d0] Power Management version 2

            Capabilities: [a4] PCI Advanced Features

            Kernel driver in use: i915

    

    00:16.0 Communication controller [0780]: Intel Corporation 6 Series/C200 Series Chipset Family MEI Controller #1 [8086:1c3a] (rev 04)

    --

    01:00.0 VGA compatible controller [0300]: NVIDIA Corporation GF108M [GeForce GT 540M] [10de:0df4] (rev ff) (prog-if ff)

            !!! Unknown header type 7f

    

    03:00.0 Network controller [0280]: Atheros Communications Inc. AR9287 Wireless Network Adapter (PCI-Express) [168c:002e] (rev 01)

            Subsystem: Foxconn International, Inc. Device [105b:e034]

            Flags: bus master, fast devsel, latency 0, IRQ 17

            Memory at f3900000 (64-bit, non-prefetchable) [size=64K]

            Capabilities: [40] Power Management version 3

            Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit-

            Capabilities: [60] Express Legacy Endpoint, MSI 00

            Capabilities: [100] Advanced Error Reporting

            Capabilities: [140] Virtual Channel

            Capabilities: [160] Device Serial Number 00-15-17-ff-ff-24-14-12

    RAMDISK$

My brightness interfaces and their values:

Code:

RAMDISK$ for i in /sys/class/backlight/*; do echo $i; cat $i/brightness; cat $i/max_brightness; done

    /sys/class/backlight/acer-wmi

    1

    15

    /sys/class/backlight/intel_backlight

    509

    976