[Bug 77451] New: No backlight on DELL XPS13 after upgrade from 3.14.4 to 3.14.5

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=77451

            Bug ID: 77451
           Summary: No backlight on DELL XPS13 after upgrade from 3.14.4
                    to 3.14.5
           Product: Drivers
           Version: 2.5
    Kernel Version: 3.14.5
          Hardware: x86-64
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Video(DRI - Intel)
          Assignee: intel-gfx-bugs at lists.freedesktop.org
          Reporter: mail at eliasprobst.eu
                CC: intel-gfx-bugs at lists.freedesktop.org
        Regression: No

Created attachment 138431
  --> https://bugzilla.kernel.org/attachment.cgi?id=138431&action=edit
Collected backlight debug data

3.14.5 breaks the backlight on a DELL XPS 13 (L322X).
The screen goes dark the moment the Kernel initializes.
The brightness FN keys don't have any effect.
A 'cat max_brightness > brightness' either.

The reason is very likely:
https://git.kernel.org/cgit/linux/kernel/git/rafael/linux-pm.git/commit/?h=linux-next&id=1811fcb029fa3eca5bd1d25eab386b0c4b80fb93

As outlined in http://hansdegoede.livejournal.com/13889.html some debug
information:

DMI data:
bios_date: 08/28/2013
bios_vendor: Dell Inc.
bios_version: A10
board_asset_tag:
board_name:
board_serial: .7CKFVW1.              .
board_vendor: Dell Inc.
board_version:
chassis_asset_tag:
chassis_serial: 7CKFVW1
chassis_type: 8
chassis_vendor: Dell Inc.
chassis_version: 0.1
product_name: XPS L322X
product_serial: 7CKFVW1
product_uuid: 44454C4C-4300-104B-8046-B7C04F565731
product_version:
sys_vendor: Dell Inc.

System is booted in UEFI-mode.

I booted with each of those options:
video.use_native_backlight=0
video.use_native_backlight=1
acpi_backlight=vendor
acpi_osi="!Windows 2012"
acpi_osi="!Windows 2009"

For each boot, I ran this hacked up script (resulting output is attached as
XZ):
#!/bin/sh
DIR="$1"
mkdir ${DIR}
ls -l /sys/class/backlight/* > ${DIR}/backlights
for backlight in /sys/class/backlight/*
do
  cat ${backlight}/brightness > ${DIR}/$(basename
${backlight})_brightness.default
  cat ${backlight}/max_brightness > ${DIR}/$(basename
${backlight})_max_brightness.default
done
echo "Please lower brightness via keyboard now, then press <ENTER>"
read something
for backlight in /sys/class/backlight/*
do
  cat ${backlight}/brightness > ${DIR}/$(basename ${backlight})_brightness.low
  cat ${backlight}/max_brightness > ${DIR}/$(basename
${backlight})_max_brightness.low
done
echo "Please increase brightness via keyboard now, then press <ENTER>"
read something
for backlight in /sys/class/backlight/*
do
  cat ${backlight}/brightness > ${DIR}/$(basename ${backlight})_brightness.high
  cat ${backlight}/max_brightness > ${DIR}/$(basename
${backlight})_max_brightness.high
done
cat /proc/cmdline > ${DIR}/cmdline
dmesg > ${DIR}/dmesg.log
grep '.*' /sys/class/dmi/id/*_* 2> /dev/null > ${DIR}/dmi.log

-- 
You are receiving this mail because:
You are on the CC list for the bug.
You are the assignee for the bug.