Asus UL30A backlight malfunction on screen off/wakeup

On UL30A Bios 212 in Oneiric Ocelot the backlight turns off as expected, but on resume the backup does not come up again, until the laptop has finished a (sw)suspend and wakeup cycle. After that the backlight works again until it blacks out again on predefinied timeout. (see additional information)

This bug is definitely reproducible.
Switching the backlight brightness level from the console using

sudo setpci -s 00:02.0 F4.B=00
sudo setpci -s 00:02.0 F4.B=ff

works well.

It may be a scripting issue.

additional information:
While the screen is switched off and backlight is off, no key or key combination will help but FN+F1 (sleep). The same applies for a lid close, if configured.
Neither setting FN+F5, nor FN+F6 nor FN+F7 nor FN+F8 nor FN+Space will switch the backlight on again.
If you use an external light, you can see shadows of the screen content, so it is definitely a backlight issue.

Using Ubuntu kernel 3.0.0-12-generic, with tuxonice ppa (does not mak a difference) and kernel options as follows:
acpi_os_name=Linux acpi_backlight=vendor

dmesg reports:
[164260.055928] [Firmware Bug]: ACPI: BIOS _OSI(Linux) query ignored

This occurs despite acpidump reports
...
[._OSIa.._O
  02e0: 53 49 0d 57 69 6e 64 6f 77 73 20 32 30 30 30 00 SI.Windows 2000.
  02f0: 70 0a 04 4f 53 56 52 a0 19 5f 4f 53 49 0d 57 69 p..OSVR.._OSI.Wi
  0300: 6e 64 6f 77 73 20 32 30 30 31 00 70 00 4f 53 56 ndows 2001.p.OSV
  0310: 52 a0 1d 5f 4f 53 49 0d 57 69 6e 64 6f 77 73 20 R.._OSI.Windows
  0320: 32 30 30 31 20 53 50 31 00 70 00 4f 53 56 52 a0 2001 SP1.p.OSVR.
  0330: 1d 5f 4f 53 49 0d 57 69 6e 64 6f 77 73 20 32 30 ._OSI.Windows 20
  0340: 30 31 20 53 50 32 00 70 00 4f 53 56 52 a0 1b 5f 01 SP2.p.OSVR.._
  0350: 4f 53 49 0d 57 69 6e 64 6f 77 73 20 32 30 30 31 OSI.Windows 2001
  0360: 2e 31 00 70 00 4f 53 56 52 a0 1f 5f 4f 53 49 0d .1.p.OSVR.._OSI.
  0370: 57 69 6e 64 6f 77 73 20 32 30 30 31 2e 31 20 53 Windows 2001.1 S
  0380: 50 31 00 70 00 4f 53 56 52 a0 19 5f 4f 53 49 0d P1.p.OSVR.._OSI.
  0390: 57 69 6e 64 6f 77 73 20 32 30 30 36 00 70 00 4f Windows 2006.p.O
  03a0: 53 56 52 a1 4e 07 a0 26 4d 43 54 48 5f 4f 53 5f SVR.N..&MCTH_OS_
  03b0: 0d 4d 69 63 72 6f 73 6f 66 74 20 57 69 6e 64 6f .Microsoft Windo
  03c0: 77 73 20 4e 54 00 70 0a 04 4f 53 56 52 a1 44 05 ws NT.p..OSVR.D.
  03d0: a0 39 4d 43 54 48 5f 4f 53 5f 0d 4d 69 63 72 6f .9MCTH_OS_.Micro
  03e0: 73 6f 66 74 20 57 69 6e 64 6f 77 73 4d 45 3a 20 soft WindowsME:
  03f0: 4d 69 6c 6c 65 6e 6e 69 75 6d 20 45 64 69 74 69 Millennium Editi
  0400: 6f 6e 00 70 0a 02 4f 53 56 52 a0 17 4d 43 54 48 on.p..OSVR..MCTH
  0410: 5f 4f 53 5f 0d 4c 69 6e 75 78 00 70 0a 03 4f 53 _OS_.Linux.p..OS
  0420: 56 52 a4 4f 53 56 52 14 4e 04 4d 43 54 48 02 a0 VR.OSVR.N.MCTH..
...

Using no acpi_backlight option will result in inusable or erratic behaviour of function key combinations.

May be related to bug: #800625, #741223, #756938