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[Daniel Jared Dominguez <1163720@xxxxxxxxxxxxxxxxxx>]

I tested on an L322X with _F_HD display and A09 BIOS in UEFI mode.

$ cat /proc/cmdline 
BOOT_IMAGE=/vmlinuz-3.11.0-14-generic root=/dev/mapper/ubuntu--vg-root ro splash quiet i915.disable_pch_pwm=0 vt.handoff=7


If I use i915.disable_pch_pwm=0 with the legacy OPROM enabled, I have to run "echo 0 > /sys/class/backlight/intel_backlight/brightness", after which the backlight keys work. If I use i915.disable_pch_pwm=1 with the legacy OPROM _disabled_, the backlight keys work without any additional work.

If I use i915.disable_pch_pwm=0 with the legacy OPROM _disabled_, your test kernel fixes the backlight issue. (However, apparently Saucy's kernel causes really bad graphics corruption if the legacy OPROM is disabled, which is a separate issue.)
And for kicks, i915.disable_pch_pwm=1 with the legacy OPROM disabled brings the system up with the backlight at its lowest setting.

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https://bugs.launchpad.net/bugs/1163720

Title:
  Brightness control broken on XPS13 and 3.8.0-16, 3.8.0-22 and
  3.11.0-12

Status in The Linux Kernel:
  Incomplete
Status in “linux” package in Ubuntu:
  Fix Released
Status in “linux” source package in Precise:
  Fix Released
Status in “linux” source package in Raring:
  In Progress

Bug description:
  Since 3.8.0-16, the brightness control doesn’t work anymore.
  The popup is displayed, so the shortcut keys do work correctly, but it has no effect on the actual brightness of the screen.

  Switching back to 3.8.0-15 solves the issue.

  ProblemType: Bug
  DistroRelease: Ubuntu 13.04
  Package: linux-image-3.8.0-16-generic 3.8.0-16.26
  ProcVersionSignature: Ubuntu 3.8.0-16.26-generic 3.8.5
  Uname: Linux 3.8.0-16-generic x86_64
  ApportVersion: 2.9.2-0ubuntu5
  Architecture: amd64
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  coucouf    1837 F.... pulseaudio
  Date: Wed Apr  3 08:29:58 2013
  DistributionChannelDescriptor:
   # This is a distribution channel descriptor
   # For more information see http://wiki.ubuntu.com/DistributionChannelDescriptor
   canonical-oem-somerville-precise-amd64-20120703-2
  HibernationDevice: RESUME=UUID=e49e9eae-f16f-45bb-ad2c-b6da5c0c6f6d
  InstallationDate: Installed on 2013-03-23 (10 days ago)
  InstallationMedia: Ubuntu 12.04 "Precise" - Build amd64 LIVE Binary 20120703-15:08
  MachineType: Dell Inc. Dell System XPS L322X
  MarkForUpload: True
  ProcEnviron:
   TERM=xterm
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=fr_FR.UTF-8
   SHELL=/bin/bash
  ProcFB: 0 inteldrmfb
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.8.0-16-generic root=UUID=3f6858e1-d8f5-44c4-b8e9-5ab8b9639ba7 ro quiet splash vt.handoff=7
  RelatedPackageVersions:
   linux-restricted-modules-3.8.0-16-generic N/A
   linux-backports-modules-3.8.0-16-generic  N/A
   linux-firmware                            1.104
  SourcePackage: linux
  UpgradeStatus: Upgraded to raring on 2013-04-02 (0 days ago)
  dmi.bios.date: 01/22/2013
  dmi.bios.vendor: Dell Inc.
  dmi.bios.version: A07
  dmi.board.name: 0PJHXN
  dmi.board.vendor: Dell Inc.
  dmi.board.version: A00
  dmi.chassis.type: 8
  dmi.chassis.vendor: Dell Inc.
  dmi.chassis.version: 0.1
  dmi.modalias: dmi:bvnDellInc.:bvrA07:bd01/22/2013:svnDellInc.:pnDellSystemXPSL322X:pvr:rvnDellInc.:rn0PJHXN:rvrA00:cvnDellInc.:ct8:cvr0.1:
  dmi.product.name: Dell System XPS L322X
  dmi.sys.vendor: Dell Inc.

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