[Latitude E6220/E6420] Brightness hotkeys are sluggish

Bug #828296 reported by Marc Legris on 2011-08-17
This bug affects 7 people
Affects Status Importance Assigned to Milestone
linux (Ubuntu)

Bug Description

Changing the brightness using the brightness hotkeys results in a very slow change. Both the OSD message and the brightness levels take much longer to work then other system's instantaneous changes.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: linux-image-3.0.0-8-generic-pae 3.0.0-8.11
ProcVersionSignature: Ubuntu 3.0.0-8.11-generic-pae 3.0.1
Uname: Linux 3.0.0-8-generic-pae i686
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
Architecture: i386
 **** List of CAPTURE Hardware Devices ****
 card 0: PCH [HDA Intel PCH], device 0: STAC92xx Analog [STAC92xx Analog]
   Subdevices: 0/1
   Subdevice #0: subdevice #0
 /dev/snd/controlC0: ubuntu 1108 F.... pulseaudio
 /dev/snd/pcmC0D0c: ubuntu 1108 F...m pulseaudio
 /dev/snd/pcmC0D0p: ubuntu 1108 F...m pulseaudio
CRDA: Error: [Errno 2] No such file or directory
 Card hw:0 'PCH'/'HDA Intel PCH at 0x3ec60000 irq 43'
   Mixer name : 'Intel CougarPoint HDMI'
   Components : 'HDA:111d76e7,102804a9,00100102 HDA:80862805,80860101,00100000'
   Controls : 27
   Simple ctrls : 13
Date: Wed Aug 17 15:19:23 2011
HibernationDevice: RESUME=UUID=f1f7a9db-8b1f-4def-accf-0602b79dff18
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Alpha i386 (20110815)
 lo no wireless extensions.

 eth0 no wireless extensions.
 Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
 Bus 001 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
 Bus 002 Device 002: ID 8087:0024 Intel Corp. Integrated Rate Matching Hub
 Bus 002 Device 003: ID 0a5c:5800 Broadcom Corp. BCM5880 Secure Applications Processor
MachineType: Dell Inc. Latitude E6220
 PATH=(custom, no user)
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.0.0-8-generic-pae root=UUID=2ada5b80-e85b-43e7-9758-9b86304e8048 ro quiet splash initcall_debug vt.handoff=7
 linux-restricted-modules-3.0.0-8-generic-pae N/A
 linux-backports-modules-3.0.0-8-generic-pae N/A
 linux-firmware 1.59
 0: dell-wifi: Wireless LAN
  Soft blocked: no
  Hard blocked: no
SourcePackage: linux
StagingDrivers: mei
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/28/2011
dmi.bios.vendor: Dell Inc.
dmi.bios.version: X29
dmi.board.name: 0862D8
dmi.board.vendor: Dell Inc.
dmi.board.version: X00
dmi.chassis.type: 9
dmi.chassis.vendor: Dell Inc.
dmi.modalias: dmi:bvnDellInc.:bvrX29:bd03/28/2011:svnDellInc.:pnLatitudeE6220:pvr01:rvnDellInc.:rn0862D8:rvrX00:cvnDellInc.:ct9:cvr:
dmi.product.name: Latitude E6220
dmi.product.version: 01
dmi.sys.vendor: Dell Inc.

Changed in linux (Ubuntu):
assignee: nobody → Chris Van Hoof (vanhoof)
summary: - [Latitude E6220] Brightness hotkeys are sluggish
+ [Latitude E6220/E6420] Brightness hotkeys are sluggish
Brad Figg (brad-figg) on 2011-08-18
Changed in linux (Ubuntu):
status: New → Confirmed
chrmhoffmann (chrmhoffmann) wrote :


I also have latitude E6420. Changing brightness with the FN+Arrow Keys is sluggish and when the automatic brightness adjustment kicks in, the laptop is kind of unusable.

Setting the brightness with intel_backlight command is instantaneous tough.

I wonder how this laptop got ubuntu certified, as it is kind of unusable through auto-brightness adjustment (or can you switch that off?).


chrmhoffmann (chrmhoffmann) wrote :

BTW: I tried latest xorg (from xorg-edgers) and latest kernel 3.1.0-rc4. Bios is A05.


Chris Van Hoof (vanhoof) on 2011-09-09
Changed in linux (Ubuntu):
assignee: Chris Van Hoof (vanhoof) → Li Li (lli5)
importance: Undecided → Medium
chrmhoffmann (chrmhoffmann) wrote :

Looks like the xf86-video-intel driver chooses the acpi_video0 driver

[ 5632.883] (II) intel(0): found backlight control interface /sys/class/backlight/acpi_video0

I have impression that changing the xf86 driver to take the intel_backlight it works better.


--- a/src/intel_display.c
+++ b/src/intel_display.c
@@ -126,9 +126,9 @@ static const char *backlight_interfaces[] = {
+ "intel_backlight",
        "acpi_video1", /* finally fallback to the generic acpi drivers */
- "intel_backlight",

chrmhoffmann (chrmhoffmann) wrote :

Possible workaround: add acpi_backlight=vendor to the kernel params (GRUB_CMDLINE_LINUX_DEFAULT in /etc/grub/default then sudo update-grub). Then the xorg driver also picks the intel_backlight.


Changed in linux (Ubuntu):
assignee: Li Li (lli5) → nobody
Changed in linux (Ubuntu):
status: Confirmed → Invalid
Mario (turanomario) wrote :

same problem on Olivetti Olibook S1530

Intel HD 3000

Mario, thank you for your comment. So your hardware and problem may be tracked, could you please file a new report with Ubuntu by executing the following in a terminal while booted into a Ubuntu repository kernel (not a mainline one) via:
ubuntu-bug linux

For more on this, please read the official Ubuntu documentation:
Ubuntu Bug Control and Ubuntu Bug Squad: https://wiki.ubuntu.com/Bugs/BestPractices#X.2BAC8-Reporting.Focus_on_One_Issue
Ubuntu Kernel Team: https://wiki.ubuntu.com/KernelTeam/KernelTeamBugPolicies#Filing_Kernel_Bug_reports
Ubuntu Community: https://help.ubuntu.com/community/ReportingBugs#Bug_reporting_etiquette

When opening up the new report, please feel free to subscribe me to it.

Thank you for your understanding.

Helpful bug reporting tips:

Brad Figg (brad-figg) on 2019-07-24
tags: added: ubuntu-certified
tags: added: cscc
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