Samsung 300V5Z Backlight

Can you give the output of:

sudo lshw -C display; lsb_release -a; uname -a

Thanks

sudo lshw -C display; lsb_release -a; uname -a
[sudo] password for nedas:
  *-display
       description: 3D controller
       product: GF119 [GeForce GT 520MX]
       vendor: NVIDIA Corporation
       physical id: 0
       bus info: pci@0000:01:00.0
       version: a1
       width: 64 bits
       clock: 33MHz
       capabilities: pm msi pciexpress bus_master cap_list
       configuration: driver=nvidia latency=0
       resources: irq:16 memory:e0000000-e0ffffff memory:b0000000-bfffffff memory:c0000000-c1ffffff ioport:3000(size=128)
  *-display
       description: VGA compatible controller
       product: 2nd Generation Core Processor Family Integrated Graphics Controller
       vendor: Intel Corporation
       physical id: 2
       bus info: pci@0000:00:02.0
       version: 09
       width: 64 bits
       clock: 33MHz
       capabilities: msi pm vga_controller bus_master cap_list rom
       configuration: driver=i915 latency=0
       resources: irq:45 memory:e1000000-e13fffff memory:d0000000-dfffffff ioport:4000(size=64)
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu precise (development branch)
Release: 12.04
Codename: precise
Linux nedas-300V3Z-300V4Z-300V5Z-200A4Y-200A5Y 3.2.0-21-generic #34-Ubuntu SMP Fri Mar 30 04:25:35 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux

this is Nvidia with optimus technology so just intel i7 processor graphics working

I sugges you report a bug. Precise is not ready and not stable

Switchable graphics causes a whole world of headaches in Linux so you may get issues there too.

Bug filled. Switchable graphics already made a headache for me :D
P.S in Oneiric with samsung-backlight mod everyting works