Bug 46401 - Brightness hotkeys have no effect on Clevo laptop
Summary: Brightness hotkeys have no effect on Clevo laptop
Status: CLOSED CODE_FIX
Alias: None
Product: ACPI
Classification: Unclassified
Component: Power-Video (show other bugs)
Hardware: All Linux
: P1 normal
Assignee: Zhang Rui
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2012-08-24 09:36 UTC by Yann
Modified: 2013-02-08 17:47 UTC (History)
5 users (show)

See Also:
Kernel Version: 3.6.2
Subsystem:
Regression: No
Bisected commit-id:


Attachments
output of lscpi -vvv from Ubuntu12.04.1 with 3.6.2-quantal mainline kernel (26.08 KB, application/octet-stream)
2012-10-18 12:21 UTC, Yann
Details
output of acpidump (190.90 KB, application/octet-stream)
2012-11-23 11:37 UTC, Yann
Details

Description Yann 2012-08-24 09:36:00 UTC
Brightness hotkeys (decrease=Fn+F8 , and increase=Fn+F9) have no effect on my Clevo (W240HU/W250HUQ) laptop.

- however, brightness control via "System Settings" -> "Brightness and lock" menu (in Ubuntu 12.04) work out-of-the-box.
- when adding the "acpi_osi=" option, hotkeys work , but the "Brightness and lock" menu has no effect any more.
- more information on http://ubuntuforums.org/showthread.php?t=2046843 and https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1041116
Comment 1 Yann 2012-10-18 11:48:46 UTC
I could reproduce this bug from kernel 2.6.32 to current mainline (3.6.2).

Please see https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1041116 for further information and logs.
Comment 2 Yann 2012-10-18 12:20:34 UTC
Here are the results of the commands asked on https://wiki.ubuntu.com/KernelTeam/KernelTeamBugPolicies#Kernel.org_Format :

[1.] One line summary of the problem:
Brightness hotkeys have no effect on Clevo laptop

[2.] Full description of the problem/report:
Brightness hotkeys (decrease=Fn+F8 , and increase=Fn+F9) have no effect on my
Clevo (W240HU/W250HUQ) laptop.
However, brightness control via "System Settings" -> "Brightness and lock"
menu (in Ubuntu 12.04) work out-of-the-box.
When adding the "acpi_osi=" option, hotkeys work , but the "Brightness and
lock" menu has no effect any more.
See https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1041116 for
further information.

[3.] Keywords:
brightness, hotkeys, kernel-bug-exists-upstream-v3.6.2

[4.] Kernel version (from /proc/version):
Linux version 3.6.2-030602-generic (apw@gomeisa) (gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) ) #201210121823 SMP Fri Oct 12 22:24:18 UTC 2012

[5.] Output of Oops.. message (if applicable)
I am not sure if it is applicable or not.

[6.] A small shell script or example program which triggers the problem (if possible)
Sorry, i don't know what to provide here.

[7.] Environment
Description:	Ubuntu 12.04.1 LTS
Release:	12.04

[7.1.] Software (add the output of the ver_linux script here)
Linux yyy-W240HU-W250HUQ 3.6.2-030602-generic #201210121823 SMP Fri Oct 12 22:24:18 UTC 2012 x86_64 x86_64 x86_64 GNU/Linux
 
Gnu C                  4.6
Gnu make               3.81
binutils               2.22
util-linux             2.20.1
mount                  support
module-init-tools      3.16
e2fsprogs              1.42
pcmciautils            018
PPP                    2.4.5
Linux C Library        2.15
Dynamic linker (ldd)   2.15
Procps                 3.2.8
Net-tools              1.60
Kbd                    1.15.2
Sh-utils               8.13
wireless-tools         30
Modules Loaded         bnep rfcomm parport_pc bluetooth ppdev binfmt_misc dm_crypt joydev snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep arc4 snd_pcm rtl8192ce rtl8192c_common rtlwifi snd_seq_midi snd_rawmidi snd_seq_midi_event mac80211 snd_seq coretemp snd_timer kvm_intel snd_seq_device kvm psmouse cfg80211 mei snd soundcore snd_page_alloc lpc_ich jmb38x_ms memstick serio_raw mac_hid lp microcode parport ghash_clmulni_intel cryptd i915 drm_kms_helper drm i2c_algo_bit jme sdhci_pci sdhci wmi video



[7.2.] Processor information (from /proc/cpuinfo):
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 42
model name	: Intel(R) Core(TM) i3-2350M CPU @ 2.30GHz
stepping	: 7
microcode	: 0x1b
cpu MHz		: 800.000
cache size	: 3072 KB
physical id	: 0
siblings	: 4
core id		: 0
cpu cores	: 2
apicid		: 0
initial apicid	: 0
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer xsave avx lahf_lm arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid
bogomips	: 4589.81
clflush size	: 64
cache_alignment	: 64
address sizes	: 36 bits physical, 48 bits virtual
power management:

processor	: 1
vendor_id	: GenuineIntel
cpu family	: 6
model		: 42
model name	: Intel(R) Core(TM) i3-2350M CPU @ 2.30GHz
stepping	: 7
microcode	: 0x1b
cpu MHz		: 800.000
cache size	: 3072 KB
physical id	: 0
siblings	: 4
core id		: 1
cpu cores	: 2
apicid		: 2
initial apicid	: 2
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer xsave avx lahf_lm arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid
bogomips	: 4589.81
clflush size	: 64
cache_alignment	: 64
address sizes	: 36 bits physical, 48 bits virtual
power management:

processor	: 2
vendor_id	: GenuineIntel
cpu family	: 6
model		: 42
model name	: Intel(R) Core(TM) i3-2350M CPU @ 2.30GHz
stepping	: 7
microcode	: 0x1b
cpu MHz		: 800.000
cache size	: 3072 KB
physical id	: 0
siblings	: 4
core id		: 0
cpu cores	: 2
apicid		: 1
initial apicid	: 1
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer xsave avx lahf_lm arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid
bogomips	: 4589.81
clflush size	: 64
cache_alignment	: 64
address sizes	: 36 bits physical, 48 bits virtual
power management:

processor	: 3
vendor_id	: GenuineIntel
cpu family	: 6
model		: 42
model name	: Intel(R) Core(TM) i3-2350M CPU @ 2.30GHz
stepping	: 7
microcode	: 0x1b
cpu MHz		: 800.000
cache size	: 3072 KB
physical id	: 0
siblings	: 4
core id		: 1
cpu cores	: 2
apicid		: 3
initial apicid	: 3
fpu		: yes
fpu_exception	: yes
cpuid level	: 13
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni pclmulqdq dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer xsave avx lahf_lm arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid
bogomips	: 4589.81
clflush size	: 64
cache_alignment	: 64
address sizes	: 36 bits physical, 48 bits virtual
power management:



[7.3.] Module information (from /proc/modules):
bnep 18315 2 - Live 0x0000000000000000
rfcomm 47922 0 - Live 0x0000000000000000
parport_pc 32866 0 - Live 0x0000000000000000
bluetooth 218412 10 bnep,rfcomm, Live 0x0000000000000000
ppdev 17113 0 - Live 0x0000000000000000
binfmt_misc 17540 1 - Live 0x0000000000000000
dm_crypt 23120 0 - Live 0x0000000000000000
joydev 17693 0 - Live 0x0000000000000000
snd_hda_codec_hdmi 32506 1 - Live 0x0000000000000000
snd_hda_codec_realtek 79668 1 - Live 0x0000000000000000
snd_hda_intel 34147 3 - Live 0x0000000000000000
snd_hda_codec 135374 3 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel, Live 0x0000000000000000
snd_hwdep 13668 1 snd_hda_codec, Live 0x0000000000000000
arc4 12573 2 - Live 0x0000000000000000
snd_pcm 97661 3 snd_hda_codec_hdmi,snd_hda_intel,snd_hda_codec, Live 0x0000000000000000
rtl8192ce 58732 0 - Live 0x0000000000000000
rtl8192c_common 49511 1 rtl8192ce, Live 0x0000000000000000
rtlwifi 76042 1 rtl8192ce, Live 0x0000000000000000
snd_seq_midi 13324 0 - Live 0x0000000000000000
snd_rawmidi 30749 1 snd_seq_midi, Live 0x0000000000000000
snd_seq_midi_event 14899 1 snd_seq_midi, Live 0x0000000000000000
mac80211 564631 3 rtl8192ce,rtl8192c_common,rtlwifi, Live 0x0000000000000000
snd_seq 61897 2 snd_seq_midi,snd_seq_midi_event, Live 0x0000000000000000
coretemp 13554 0 - Live 0x0000000000000000
snd_timer 29989 2 snd_pcm,snd_seq, Live 0x0000000000000000
kvm_intel 137895 0 - Live 0x0000000000000000
snd_seq_device 14497 3 snd_seq_midi,snd_rawmidi,snd_seq, Live 0x0000000000000000
kvm 437435 1 kvm_intel, Live 0x0000000000000000
psmouse 92362 0 - Live 0x0000000000000000
cfg80211 212917 2 rtlwifi,mac80211, Live 0x0000000000000000
mei 41409 0 - Live 0x0000000000000000
snd 79391 16 snd_hda_codec_hdmi,snd_hda_codec_realtek,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_pcm,snd_rawmidi,snd_seq,snd_timer,snd_seq_device, Live 0x0000000000000000
soundcore 15091 1 snd, Live 0x0000000000000000
snd_page_alloc 18572 2 snd_hda_intel,snd_pcm, Live 0x0000000000000000
lpc_ich 17144 0 - Live 0x0000000000000000
jmb38x_ms 17646 0 - Live 0x0000000000000000
memstick 16605 1 jmb38x_ms, Live 0x0000000000000000
serio_raw 13215 0 - Live 0x0000000000000000
mac_hid 13253 0 - Live 0x0000000000000000
lp 17799 0 - Live 0x0000000000000000
microcode 23040 0 - Live 0x0000000000000000
parport 46562 3 parport_pc,ppdev,lp, Live 0x0000000000000000
ghash_clmulni_intel 13180 0 - Live 0x0000000000000000
cryptd 20530 1 ghash_clmulni_intel, Live 0x0000000000000000
i915 550154 3 - Live 0x0000000000000000
drm_kms_helper 46931 1 i915, Live 0x0000000000000000
drm 277074 4 i915,drm_kms_helper, Live 0x0000000000000000
i2c_algo_bit 13564 1 i915, Live 0x0000000000000000
jme 45401 0 - Live 0x0000000000000000
sdhci_pci 18748 0 - Live 0x0000000000000000
sdhci 33144 1 sdhci_pci, Live 0x0000000000000000
wmi 19256 0 - Live 0x0000000000000000
video 19412 1 i915, Live 0x0000000000000000





[7.4.] Loaded driver and hardware information (/proc/ioports, /proc/iomem)
$ cat /proc/ioports
0000-0cf7 : PCI Bus 0000:00
  0000-001f : dma1
  0020-0021 : pic1
  0040-0043 : timer0
  0050-0053 : timer1
  0060-0060 : keyboard
  0062-0062 : EC data
  0064-0064 : keyboard
  0066-0066 : EC cmd
  0070-0077 : rtc0
  0080-008f : dma page reg
  00a0-00a1 : pic2
  00c0-00df : dma2
  00f0-00ff : fpu
  0200-020f : pnp 00:04
  0400-0453 : pnp 00:04
    0400-0403 : ACPI PM1a_EVT_BLK
    0404-0405 : ACPI PM1a_CNT_BLK
    0408-040b : ACPI PM_TMR
    0410-0415 : ACPI CPU throttle
    0420-042f : ACPI GPE0_BLK
    0430-0433 : iTCO_wdt
    0450-0450 : ACPI PM2_CNT_BLK
  0454-0457 : pnp 00:06
  0458-047f : pnp 00:04
    0460-047f : iTCO_wdt
  04d0-04d1 : pnp 00:07
  0500-057f : pnp 00:04
  0680-069f : pnp 00:04
0cf8-0cff : PCI conf1
0d00-ffff : PCI Bus 0000:00
  164e-164f : pnp 00:04
  d000-dfff : PCI Bus 0000:03
    d000-d0ff : 0000:03:00.0
      d000-d0ff : jme
    d100-d17f : 0000:03:00.0
      d100-d17f : jme
  e000-efff : PCI Bus 0000:02
    e000-e0ff : 0000:02:00.0
      e000-e0ff : rtlwifi
  f000-f03f : 0000:00:02.0
  f040-f05f : 0000:00:1f.3
  f060-f07f : 0000:00:1f.2
    f060-f07f : ahci
  f080-f083 : 0000:00:1f.2
    f080-f083 : ahci
  f090-f097 : 0000:00:1f.2
    f090-f097 : ahci
  f0a0-f0a3 : 0000:00:1f.2
    f0a0-f0a3 : ahci
  f0b0-f0b7 : 0000:00:1f.2
    f0b0-f0b7 : ahci
  ffff-ffff : pnp 00:04
    ffff-ffff : pnp 00:04


$ cat /proc/iomem
00000000-0000ffff : reserved
00010000-0009d7ff : System RAM
0009d800-0009ffff : reserved
000a0000-000bffff : PCI Bus 0000:00
000c0000-000ce7ff : Video ROM
000ce800-000cf7ff : Adapter ROM
000d0000-000d3fff : PCI Bus 0000:00
000d4000-000d7fff : PCI Bus 0000:00
000d8000-000dbfff : PCI Bus 0000:00
000dc000-000dffff : PCI Bus 0000:00
000e0000-000fffff : reserved
  000e0000-000e3fff : PCI Bus 0000:00
  000e4000-000e7fff : PCI Bus 0000:00
  000f0000-000fffff : System ROM
00100000-1fffffff : System RAM
  01000000-016ab6aa : Kernel code
  016ab6ab-01ce033f : Kernel data
  01dd7000-01f31fff : Kernel bss
20000000-201fffff : reserved
20200000-3fffffff : System RAM
40000000-401fffff : reserved
40200000-da531fff : System RAM
da532000-da574fff : ACPI Non-volatile Storage
da575000-da7e0fff : System RAM
da7e1000-da966fff : reserved
da967000-dacebfff : System RAM
dacec000-dad67fff : reserved
dad68000-dafe7fff : ACPI Non-volatile Storage
dafe8000-daffffff : ACPI Tables
db000000-db7fffff : RAM buffer
db800000-df9fffff : reserved
dfa00000-feafffff : PCI Bus 0000:00
  dfa00000-dfa00fff : pnp 00:0b
  e0000000-efffffff : 0000:00:02.0
  f7800000-f7bfffff : 0000:00:02.0
  f7c00000-f7cfffff : PCI Bus 0000:03
    f7c00000-f7c0ffff : 0000:03:00.0
    f7c10000-f7c1ffff : 0000:03:00.0
      f7c10000-f7c1ffff : jme
    f7c20000-f7c23fff : 0000:03:00.0
      f7c20000-f7c23fff : jme
    f7c24000-f7c240ff : 0000:03:00.3
      f7c24000-f7c240ff : jmb38x_ms
    f7c25000-f7c250ff : 0000:03:00.2
    f7c26000-f7c260ff : 0000:03:00.1
      f7c26000-f7c260ff : mmc0
  f7d00000-f7dfffff : PCI Bus 0000:02
    f7d00000-f7d03fff : 0000:02:00.0
      f7d00000-f7d03fff : rtlwifi
  f7e00000-f7e03fff : 0000:00:1b.0
    f7e00000-f7e03fff : ICH HD audio
  f7e05000-f7e050ff : 0000:00:1f.3
  f7e06000-f7e067ff : 0000:00:1f.2
    f7e06000-f7e067ff : ahci
  f7e07000-f7e073ff : 0000:00:1d.0
    f7e07000-f7e073ff : ehci_hcd
  f7e08000-f7e083ff : 0000:00:1a.0
    f7e08000-f7e083ff : ehci_hcd
  f7e0a000-f7e0a00f : 0000:00:16.0
    f7e0a000-f7e0a00f : mei
  f8000000-fbffffff : PCI MMCONFIG 0000 [bus 00-3f]
    f8000000-fbffffff : reserved
      f8000000-fbffffff : pnp 00:0b
fec00000-fec00fff : reserved
  fec00000-fec003ff : IOAPIC 0
fed00000-fed03fff : reserved
  fed00000-fed003ff : HPET 0
fed10000-fed17fff : pnp 00:0b
fed18000-fed18fff : pnp 00:0b
fed19000-fed19fff : pnp 00:0b
fed1c000-fed1ffff : reserved
  fed1c000-fed1ffff : pnp 00:0b
    fed1f410-fed1f414 : iTCO_wdt
fed20000-fed3ffff : pnp 00:0b
fed40000-fed44fff : PCI Bus 0000:00
fed45000-fed8ffff : pnp 00:0b
fed90000-fed93fff : pnp 00:0b
fee00000-fee00fff : Local APIC
  fee00000-fee00fff : reserved
ff000000-ffffffff : reserved
  ff000000-ffffffff : pnp 00:0b
100000000-11fdfffff : System RAM
11fe00000-11fffffff : RAM buffer




[7.5.] PCI information ('lspci -vvv' as root)
Attached file. (lspci_vvv_3.6.2)



[7.6.] SCSI information (from /proc/scsi/scsi)
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
  Vendor: ATA      Model: ST9500325AS      Rev: 0001
  Type:   Direct-Access                    ANSI  SCSI revision: 05
Host: scsi2 Channel: 00 Id: 00 Lun: 00
  Vendor: MATSHITA Model: DVD-RAM UJ8B0    Rev: 1.00
  Type:   CD-ROM                           ANSI  SCSI revision: 05



[7.7.] Other information that might be relevant to the problem (please look in /proc and include all information that you think to be relevant):
$ ls /proc
1     1510  1629  18    2634  371  735        consoles       modules
10    1517  1631  1804  2649  38   768        cpuinfo        mounts
1009  1520  1634  1808  2652  39   771        crypto         mtrr
1010  1521  1639  1810  2659  4    8          devices        net
1021  1530  1645  1829  2660  40   833        diskstats      pagetypeinfo
1024  1533  1648  1835  27    41   834        dma            partitions
1027  1537  1649  1840  2721  42   882        dri            sched_debug
1028  1540  1654  1873  28    43   89         driver         schedstat
1053  1548  167   19    2871  44   9          execdomains    scsi
1056  1551  1671  1908  29    486  90         fb             self
1061  1554  1673  1960  2929  5    91         filesystems    slabinfo
1065  1556  1682  1963  2930  53   941        fs             softirqs
1074  1570  1684  1970  2987  57   948        interrupts     stat
1083  1574  1687  2     299   58   958        iomem          swaps
1101  1579  1696  20    3     59   959        ioports        sys
12    1582  17    2016  30    60   960        irq            sysrq-trigger
1216  1584  1701  2029  300   61   962        kallsyms       sysvipc
1220  1586  1703  2048  3044  616  973        kcore          timer_list
1236  1589  1713  21    31    62   980        key-users      timer_stats
1238  1590  1731  2121  3114  63   982        kmsg           tty
13    1591  1745  22    3122  643  998        kpagecount     uptime
1335  1597  1747  23    3123  644  999        kpageflags     version
1371  1599  1749  2362  3181  7    acpi       latency_stats  vmallocinfo
14    16    1751  24    32    70   asound     loadavg        vmstat
1455  1600  1773  25    3237  717  buddyinfo  locks          zoneinfo
1470  1615  1783  26    33    726  bus        mdstat
1481  1617  1785  2628  34    728  cgroups    meminfo
15    1618  1791  2632  368   732  cmdline    misc



[X.] Workaround with drawback:
Adding the "acpi_osi=" kernel option makes the brightness hotkeys work, but it has a drawback: the "System Parameters" --> "Brightness and lock" menu does not work any more (the cursor does not allow to change the brightness any more).
Comment 3 Yann 2012-10-18 12:21:36 UTC
Created attachment 83841 [details]
output of lscpi -vvv from Ubuntu12.04.1 with 3.6.2-quantal mainline kernel
Comment 4 Zhang Rui 2012-11-13 07:28:26 UTC
does "poking /sys/class/backlight/*/*" change the backlight?
Comment 5 Yann 2012-11-13 09:59:46 UTC
Thanks Zhang for your interest in this issue.
What do you mean by "poking /sys/class/backlight/*/*" ?

I guess this is what you want: http://ubuntuforums.org/showthread.php?t=2046843&page=2
Comment 6 Zhang Rui 2012-11-14 01:12:43 UTC
it says that
1~7 works for /sys/class/backlight/acpi_video0/brightness
is it true? changing its value can change the real backlight, right?
Comment 7 Yann 2012-11-14 08:37:13 UTC
Yes.
I just reproduced on Ubuntu12.10 (default kernel: 3.5.0-18). Works from 0 to 7. Fails with 8 and superior.

http://ubuntuforums.org/showpost.php?p=12353678&postcount=30
Comment 8 Zhang Rui 2012-11-21 01:25:04 UTC
please attach the output of "grep . /sys/class/backlight/*/*"
Comment 9 Yann 2012-11-21 14:11:31 UTC
$grep . /sys/class/backlight/*/*
/sys/class/backlight/acpi_video0/actual_brightness:7
/sys/class/backlight/acpi_video0/bl_power:0
/sys/class/backlight/acpi_video0/brightness:7
grep: /sys/class/backlight/acpi_video0/device: Is a directory
/sys/class/backlight/acpi_video0/max_brightness:7
grep: /sys/class/backlight/acpi_video0/power: Is a directory
grep: /sys/class/backlight/acpi_video0/subsystem: Is a directory
/sys/class/backlight/acpi_video0/type:firmware
/sys/class/backlight/intel_backlight/actual_brightness:4882
/sys/class/backlight/intel_backlight/bl_power:0
/sys/class/backlight/intel_backlight/brightness:4882
grep: /sys/class/backlight/intel_backlight/device: Is a directory
/sys/class/backlight/intel_backlight/max_brightness:4882
grep: /sys/class/backlight/intel_backlight/power: Is a directory
grep: /sys/class/backlight/intel_backlight/subsystem: Is a directory
/sys/class/backlight/intel_backlight/type:raw
Comment 10 Zhang Rui 2012-11-23 07:21:27 UTC
please attach the acpidump output of your machine.
BTW, does "echo {0, 4880} > /sys/class/backlight/intel_backlight/brightness" change the backlight?
Comment 11 Yann 2012-11-23 11:37:41 UTC
Created attachment 87111 [details]
output of acpidump

Please find in attached file the output of acpidump (from my installed 12.10 session)

No, changing the value of /sys/class/backlight/intel_backlight/brightness does not change the real backlight.
Comment 12 Zhang Rui 2012-11-28 15:05:16 UTC
please boot with
1. acpi_osi="!Windows 2009" acpi_osi="!Windows 2006"
2. acpi_osi="!Windows 2009"
does anyone of this also works?
Comment 13 Yann 2012-11-28 23:01:23 UTC
1. hotkeys work , but the "Brightness and lock" cursor (in System Parameters menu) has no effect any more.
2. no effect
Comment 14 Zhang Rui 2012-11-29 04:49:03 UTC
so does the backlight change if you poke /sys/class/backlight/acpi_video0/brightness?
Comment 15 Zhang Rui 2012-11-29 04:49:50 UTC
(In reply to comment #14)
> so does the backlight change if you poke
> /sys/class/backlight/acpi_video0/brightness?

when you boot with acpi_osi="!Windows 2009" AND acpi_osi="!Windows 2006".
Comment 16 Yann 2012-11-29 23:14:46 UTC
No, it doesn't.
Comment 17 Peter Wu 2012-12-15 11:13:47 UTC
This is very likely the same bug as https://bugs.freedesktop.org/show_bug.cgi?id=45452, which should be fixed in 3.7. YannUbuntu, can you try that kernel?
Comment 18 Yann 2012-12-16 02:08:27 UTC
Thanks Peter.
The bug is fixed in kernel 3.7.0.
Marking [RESOLVED]

Thanks to everybody who contributed!

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