Whenever I try to change the backlight brightness with the fn+f1 or fn+f2 keys, the gui does show that the brightness is being adjusted. However the actual brightness stays the same, until I get to the absolute lowest value possible, then the backlight just turns off completely (which I can then turn back on again by increasing the brightness again). I've also changed my grub settings as suggested by this question but that doesn't fix things for me.

When I look at /sys/class/backlight I only have the intel_backlight folder. When try echo'ing into the brightness file inside that folder (as suggested by some other answers on here) I get the same result as with the fn keys: the backlight stays at maximum brightness until I enter 0 as a value, then it just turns off.

I'm currently on 14.10, but I had the same problem in 14.04. Is there any way I can fix this, even if it's just a manual way of controlling the brightness, since then I can at least look at my screen again without burning my retinas.


~$ sudo lshw -C Display
   description: VGA compatible controller
   product: 3rd Gen Core processor 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:f7800000-f7bfffff memory:e0000000-efffffff ioport:f000(size=64)


 ~$ lsmod
Module                  Size  Used by
ctr                    13049  1 
ccm                    17731  1 
bnep                   19543  2 
rfcomm                 69509  8 
binfmt_misc            17468  1 
nls_iso8859_1          12713  1 
uvcvideo               81065  0 
videobuf2_vmalloc      13216  1 uvcvideo
videobuf2_memops       13362  1 videobuf2_vmalloc
videobuf2_core         59104  1 uvcvideo
 v4l2_common            15682  1 videobuf2_core
videodev              149725  3 uvcvideo,v4l2_common,videobuf2_core
media                  21963  2 uvcvideo,videodev
arc4                   12608  2 
iwldvm                236430  0 
mac80211              660592  1 iwldvm
snd_hda_codec_hdmi     47547  1 
snd_hda_codec_realtek    76887  1 
snd_hda_codec_generic    68914  1 snd_hda_codec_realtek
intel_rapl             18783  0 
x86_pkg_temp_thermal    14205  0 
intel_powerclamp       18786  0 
coretemp               13441  0 
dm_multipath           22843  0 
kvm_intel             143553  0 
scsi_dh                14882  1 dm_multipath
kvm                   459843  1 kvm_intel
crct10dif_pclmul       14307  0 
snd_hda_intel          30379  5 
crc32_pclmul           13133  0 
snd_hda_controller     35152  1 snd_hda_intel
ghash_clmulni_intel    13230  0 
snd_hda_codec         139675  5       
         snd_hda_codec_realtek,snd_hda_codec_hdmi,snd_hda_codec_generic,snd_hda_intel,snd_hda_c     ontroller
snd_hwdep              17698  1 snd_hda_codec
aesni_intel           152552  2 
aes_x86_64             17131  1 aesni_intel
lrw                    13287  1 aesni_intel
gf128mul               14951  1 lrw
glue_helper            13944  1 aesni_intel
ablk_helper            13597  1 aesni_intel
    cryptd                 20360  3 ghash_clmulni_intel,aesni_intel,ablk_helper
snd_pcm               104102  5         snd_hda_codec_hdmi,snd_hda_codec,snd_hda_intel,snd_hda_controller
snd_seq_midi           13564  0 
snd_seq_midi_event     14899  1 snd_seq_midi
snd_rawmidi            30876  1 snd_seq_midi
joydev                 17344  0 
snd_seq                67224  2 snd_seq_midi_event,snd_seq_midi
serio_raw              13434  0 
snd_seq_device         14497  3 snd_seq,snd_rawmidi,snd_seq_midi
snd_timer              29513  2 snd_pcm,snd_seq
iwlwifi               182909  1 iwldvm
snd                    87611  20     snd_hda_codec_realtek,snd_hwdep,snd_timer,snd_hda_codec_hdmi,snd_pcm,snd_seq,snd_rawmi    di,snd_hda_codec_generic,snd_hda_codec,snd_hda_intel,snd_seq_device
lpc_ich                21093  0 
cfg80211              510218  3 iwlwifi,mac80211,iwldvm
btusb                  32448  0 
bluetooth             446190  22 bnep,btusb,rfcomm
mei_me                 19742  0 
mei                    87931  1 mei_me
shpchp                 37040  0 
soundcore              15052  2 snd,snd_hda_codec
6lowpan_iphc           18702  1 bluetooth
mac_hid                13227  0 
parport_pc             32741  0 
ppdev                  17671  0 
lp                     17759  0 
parport                42299  3 lp,ppdev,parport_pc
btrfs                 911467  0 
xor                    21411  1 btrfs
raid6_pq               97812  1 btrfs
dm_mirror              22040  0 
dm_region_hash         20850  1 dm_mirror
dm_log                 18411  2 dm_region_hash,dm_mirror
i915                  917618  4 
i2c_algo_bit           13406  1 i915
psmouse               106548  0 
drm_kms_helper         61627  1 i915
r8169                  71471  0 
mii                    13934  1 r8169
drm                   310919  6 i915,drm_kms_helper
ahci                   34062  3 
libahci                32424  1 ahci
wmi                    19193  0 
video                  20128  1 i915


~$ modinfo i915
filename:       /lib/modules/3.16.0-24-generic/kernel/drivers/gpu/drm/i915/i915.ko
license:        GPL and additional rights
description:    Intel Graphics
author:         Tungsten Graphics, Inc.
srcversion:     05B59F886C9F39DA145FE73
alias:          pci:v00008086d000022B3sv*sd*bc03sc*i*
alias:          pci:v00008086d000022B2sv*sd*bc03sc*i*
alias:          pci:v00008086d000022B1sv*sd*bc03sc*i*
alias:          pci:v00008086d000022B0sv*sd*bc03sc*i*
alias:          pci:v00008086d0000162Dsv*sd*bc03sc*i*
alias:          pci:v00008086d0000162Asv*sd*bc03sc*i*
alias:          pci:v00008086d0000162Esv*sd*bc03sc*i*
alias:          pci:v00008086d0000162Bsv*sd*bc03sc*i*
alias:          pci:v00008086d00001626sv*sd*bc03sc*i*
alias:          pci:v00008086d00001622sv*sd*bc03sc*i*
alias:          pci:v00008086d0000161Dsv*sd*bc03sc*i*
alias:          pci:v00008086d0000161Asv*sd*bc03sc*i*
alias:          pci:v00008086d0000160Dsv*sd*bc03sc*i*
alias:          pci:v00008086d0000160Asv*sd*bc03sc*i*
alias:          pci:v00008086d0000161Esv*sd*bc03sc*i*
alias:          pci:v00008086d0000161Bsv*sd*bc03sc*i*
alias:          pci:v00008086d00001616sv*sd*bc03sc*i*
alias:          pci:v00008086d00001612sv*sd*bc03sc*i*
alias:          pci:v00008086d0000160Esv*sd*bc03sc*i*
alias:          pci:v00008086d0000160Bsv*sd*bc03sc*i*
alias:          pci:v00008086d00001606sv*sd*bc03sc*i*
alias:          pci:v00008086d00001602sv*sd*bc03sc*i*
alias:          pci:v00008086d00000155sv*sd*bc03sc*i*
alias:          pci:v00008086d00000157sv*sd*bc03sc*i*
alias:          pci:v00008086d00000F33sv*sd*bc03sc*i*
alias:          pci:v00008086d00000F32sv*sd*bc03sc*i*
alias:          pci:v00008086d00000F31sv*sd*bc03sc*i*
alias:          pci:v00008086d00000F30sv*sd*bc03sc*i*
alias:          pci:v00008086d00000D26sv*sd*bc03sc*i*
alias:          pci:v00008086d00000D16sv*sd*bc03sc*i*
alias:          pci:v00008086d00000D06sv*sd*bc03sc*i*
alias:          pci:v00008086d00000A2Esv*sd*bc03sc*i*
alias:          pci:v00008086d00000A1Esv*sd*bc03sc*i*
alias:          pci:v00008086d00000A0Esv*sd*bc03sc*i*
alias:          pci:v00008086d00000A26sv*sd*bc03sc*i*
alias:          pci:v00008086d00000A16sv*sd*bc03sc*i*
alias:          pci:v00008086d00000A06sv*sd*bc03sc*i*
alias:          pci:v00008086d00000C26sv*sd*bc03sc*i*
alias:          pci:v00008086d00000C16sv*sd*bc03sc*i*
alias:          pci:v00008086d00000C06sv*sd*bc03sc*i*
alias:          pci:v00008086d00000426sv*sd*bc03sc*i*
alias:          pci:v00008086d00000416sv*sd*bc03sc*i*
alias:          pci:v00008086d00000406sv*sd*bc03sc*i*
alias:          pci:v00008086d00000D2Esv*sd*bc03sc*i*
alias:          pci:v00008086d00000D1Esv*sd*bc03sc*i*
alias:          pci:v00008086d00000D0Esv*sd*bc03sc*i*
alias:          pci:v00008086d00000D2Bsv*sd*bc03sc*i*
alias:          pci:v00008086d00000D1Bsv*sd*bc03sc*i*
alias:          pci:v00008086d00000D0Bsv*sd*bc03sc*i*
alias:          pci:v00008086d00000D2Asv*sd*bc03sc*i*
alias:          pci:v00008086d00000D1Asv*sd*bc03sc*i*
alias:          pci:v00008086d00000D0Asv*sd*bc03sc*i*
alias:          pci:v00008086d00000D22sv*sd*bc03sc*i*
alias:          pci:v00008086d00000D12sv*sd*bc03sc*i*
alias:          pci:v00008086d00000D02sv*sd*bc03sc*i*
alias:          pci:v00008086d00000A2Bsv*sd*bc03sc*i*
alias:          pci:v00008086d00000A1Bsv*sd*bc03sc*i*
alias:          pci:v00008086d00000A0Bsv*sd*bc03sc*i*
alias:          pci:v00008086d00000A2Asv*sd*bc03sc*i*
alias:          pci:v00008086d00000A1Asv*sd*bc03sc*i*
alias:          pci:v00008086d00000A0Asv*sd*bc03sc*i*
alias:          pci:v00008086d00000A22sv*sd*bc03sc*i*
alias:          pci:v00008086d00000A12sv*sd*bc03sc*i*
alias:          pci:v00008086d00000A02sv*sd*bc03sc*i*
alias:          pci:v00008086d00000C2Esv*sd*bc03sc*i*
alias:          pci:v00008086d00000C1Esv*sd*bc03sc*i*
alias:          pci:v00008086d00000C0Esv*sd*bc03sc*i*
alias:          pci:v00008086d00000C2Bsv*sd*bc03sc*i*
alias:          pci:v00008086d00000C1Bsv*sd*bc03sc*i*
alias:          pci:v00008086d00000C0Bsv*sd*bc03sc*i*
alias:          pci:v00008086d00000C2Asv*sd*bc03sc*i*
alias:          pci:v00008086d00000C1Asv*sd*bc03sc*i*
alias:          pci:v00008086d00000C0Asv*sd*bc03sc*i*
alias:          pci:v00008086d00000C22sv*sd*bc03sc*i*
alias:          pci:v00008086d00000C12sv*sd*bc03sc*i*
alias:          pci:v00008086d00000C02sv*sd*bc03sc*i*
alias:          pci:v00008086d0000042Esv*sd*bc03sc*i*
alias:          pci:v00008086d0000041Esv*sd*bc03sc*i*
alias:          pci:v00008086d0000040Esv*sd*bc03sc*i*
alias:          pci:v00008086d0000042Bsv*sd*bc03sc*i*
alias:          pci:v00008086d0000041Bsv*sd*bc03sc*i*
alias:          pci:v00008086d0000040Bsv*sd*bc03sc*i*
alias:          pci:v00008086d0000042Asv*sd*bc03sc*i*
alias:          pci:v00008086d0000041Asv*sd*bc03sc*i*
alias:          pci:v00008086d0000040Asv*sd*bc03sc*i*
alias:          pci:v00008086d00000422sv*sd*bc03sc*i*
alias:          pci:v00008086d00000412sv*sd*bc03sc*i*
alias:          pci:v00008086d00000402sv*sd*bc03sc*i*
alias:          pci:v00008086d0000016Asv*sd*bc03sc*i*
alias:          pci:v00008086d0000015Asv*sd*bc03sc*i*
alias:          pci:v00008086d00000162sv*sd*bc03sc*i*
alias:          pci:v00008086d00000152sv*sd*bc03sc*i*
alias:          pci:v00008086d00000166sv*sd*bc03sc*i*
alias:          pci:v00008086d00000156sv*sd*bc03sc*i*
alias:          pci:v00008086d0000016Asv0000152Dsd00008990bc03sc*i*
alias:          pci:v00008086d00000126sv*sd*bc03sc*i*
alias:          pci:v00008086d00000116sv*sd*bc03sc*i*
alias:          pci:v00008086d00000106sv*sd*bc03sc*i*
alias:          pci:v00008086d0000010Asv*sd*bc03sc*i*
alias:          pci:v00008086d00000122sv*sd*bc03sc*i*
alias:          pci:v00008086d00000112sv*sd*bc03sc*i*
alias:          pci:v00008086d00000102sv*sd*bc03sc*i*
alias:          pci:v00008086d00000046sv*sd*bc03sc*i*
alias:          pci:v00008086d00000042sv*sd*bc03sc*i*
alias:          pci:v00008086d0000A011sv*sd*bc03sc*i*
alias:          pci:v00008086d0000A001sv*sd*bc03sc*i*
alias:          pci:v00008086d00002E92sv*sd*bc03sc*i*
alias:          pci:v00008086d00002E42sv*sd*bc03sc*i*
alias:          pci:v00008086d00002E32sv*sd*bc03sc*i*
alias:          pci:v00008086d00002E22sv*sd*bc03sc*i*
alias:          pci:v00008086d00002E12sv*sd*bc03sc*i*
alias:          pci:v00008086d00002E02sv*sd*bc03sc*i*
alias:          pci:v00008086d00002A42sv*sd*bc03sc*i*
alias:          pci:v00008086d00002A12sv*sd*bc03sc*i*
alias:          pci:v00008086d00002A02sv*sd*bc03sc*i*
alias:          pci:v00008086d000029D2sv*sd*bc03sc*i*
alias:          pci:v00008086d000029C2sv*sd*bc03sc*i*
alias:          pci:v00008086d000029B2sv*sd*bc03sc*i*
alias:          pci:v00008086d000029A2sv*sd*bc03sc*i*
alias:          pci:v00008086d00002992sv*sd*bc03sc*i*
alias:          pci:v00008086d00002982sv*sd*bc03sc*i*
alias:          pci:v00008086d00002972sv*sd*bc03sc*i*
alias:          pci:v00008086d000027AEsv*sd*bc03sc*i*
alias:          pci:v00008086d000027A2sv*sd*bc03sc*i*
alias:          pci:v00008086d00002772sv*sd*bc03sc*i*
alias:          pci:v00008086d00002592sv*sd*bc03sc*i*
alias:          pci:v00008086d0000258Asv*sd*bc03sc*i*
alias:          pci:v00008086d00002582sv*sd*bc03sc*i*
alias:          pci:v00008086d00002572sv*sd*bc03sc*i*
alias:          pci:v00008086d0000358Esv*sd*bc03sc*i*
alias:          pci:v00008086d00003582sv*sd*bc03sc*i*
alias:          pci:v00008086d00002562sv*sd*bc03sc*i*
alias:          pci:v00008086d00003577sv*sd*bc03sc*i*
depends:        drm_kms_helper,drm,video,i2c-algo-bit
intree:         Y
vermagic:       3.16.0-24-generic SMP mod_unload modversions 
signer:         Magrathea: Glacier signing key
sig_key:        3C:88:40:D1:7B:DF:90:2E:17:1E:23:B4:BB:C2:72:8E:B6:94:C7:0A
sig_hashalgo:   sha512
parm:           modeset:Use kernel modesetting [KMS] (0=DRM_I915_KMS from .config,     1=on, -1=force vga console preference [default]) (int)
parm:           panel_ignore_lid:Override lid status (0=autodetect, 1=autodetect     disabled [default], -1=force lid closed, -2=force lid open) (int)
parm:           powersave:Enable powersavings, fbc, downclocking, etc. (default:     true) (int)
parm:           semaphores:Use semaphores for inter-ring sync (default: -1 (use     per-chip defaults)) (int)
parm:           enable_rc6:Enable power-saving render C-state 6. Different stages     can be selected via bitmask values (0 = disable; 1 = enable rc6; 2 = enable deep rc6;     4 = enable deepest rc6). For example, 3 would enable rc6 and deep rc6, and 7 would     enable everything. default: -1 (use per-chip default) (int)
parm:           enable_fbc:Enable frame buffer compression for power savings     (default: -1 (use per-chip default)) (int)
parm:           lvds_downclock:Use panel (LVDS/eDP) downclocking for power savings     (default: false) (int)
parm:           lvds_channel_mode:Specify LVDS channel mode (0=probe BIOS     [default], 1=single-channel, 2=dual-channel) (int)
parm:           lvds_use_ssc:Use Spread Spectrum Clock with panels [LVDS/eDP]     (default: auto from VBT) (int)
parm:           vbt_sdvo_panel_type:Override/Ignore selection of SDVO panel mode     in the VBT (-2=ignore, -1=auto [default], index in VBT BIOS table) (int)
parm:           reset:Attempt GPU resets (default: true) (bool)
parm:           enable_hangcheck:Periodically check GPU activity for detecting     hangs. WARNING: Disabling this can cause system wide hangs. (default: true) (bool)
parm:           enable_ppgtt:Override PPGTT usage. (-1=auto [default], 0=disabled,     1=aliasing, 2=full) (int)
parm:           enable_psr:Enable PSR (default: false) (int)
parm:           preliminary_hw_support:Enable preliminary hardware support. (int)
parm:           disable_power_well:Disable the power well when possible (default:     true) (int)
parm:           enable_ips:Enable IPS (default: true) (int)
parm:           fastboot:Try to skip unnecessary mode sets at boot time (default:     false) (bool)
parm:           prefault_disable:Disable page prefaulting for pread/pwrite/reloc     (default:false). For developers only. (bool)
parm:           invert_brightness:Invert backlight brightness (-1 force normal, 0     machine defaults, 1 force inversion), please report PCI device ID, subsystem vendor     and subsystem device ID to dri-devel@lists.freedesktop.org, if your machine needs it.     It will then be included in an upcoming module version. (int)
parm:           disable_display:Disable display (default: false) (bool)
parm:           disable_vtd_wa:Disable all VT-d workarounds (default: false)     (bool)
parm:           enable_cmd_parser:Enable command parsing (1=enabled [default],     0=disabled) (int)
  • Please edit your question to include the output of lshw -C Display, lsmod and modinfo i915. – Jan Nov 15 '14 at 17:52
  • Ok, I added the output of those three programs in my edit. – user717572 Nov 15 '14 at 20:35
  • Perhaps this is a bug in the i915 driver, ask the experts on the intel-gfx@lists.freedesktop.org mailing list... – Jan Nov 15 '14 at 20:40
  • Can anyone please help me find a way to diagnose the problem more? I really have to fix this because at this moment my laptop isn't usable in the evening/night... :( – user717572 Nov 17 '14 at 19:36
  • Have you written an email to the driver developers' mailing list as advised? – Jan Nov 17 '14 at 21:38

Edit your '/etc/default/grub' and find the line the says


Add these values

acpi_backlight=vendor acpi_osi=Linux

Regenerate grub from command line

sudo update-grub

Reboot your system.

  • Thank you for the suggestion, but this didn't change it for me. – user717572 Nov 16 '14 at 21:16

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