Bug 909552 - Brightness/Backlight adjustement does not work anymore on Dell Inspiron 15r
Summary: Brightness/Backlight adjustement does not work anymore on Dell Inspiron 15r
Keywords:
Status: CLOSED NEXTRELEASE
Alias: None
Product: Fedora
Classification: Fedora
Component: kernel
Version: 20
Hardware: x86_64
OS: Linux
unspecified
medium
Target Milestone: ---
Assignee: Kernel Maintainer List
QA Contact: Fedora Extras Quality Assurance
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2013-02-09 10:41 UTC by Téo M.
Modified: 2014-05-21 17:22 UTC (History)
14 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2014-05-21 17:22:03 UTC
Type: Bug
Embargoed:


Attachments (Terms of Use)
output of acpidump (258.79 KB, text/plain)
2014-05-08 12:52 UTC, Téo M.
no flags Details
output of dmesg (66.00 KB, text/plain)
2014-05-08 12:52 UTC, Téo M.
no flags Details
output or dmidecode (22.25 KB, text/plain)
2014-05-09 16:49 UTC, Téo M.
no flags Details
add debug prints to verify what's going wrong (571 bytes, patch)
2014-05-10 08:57 UTC, Aaron Lu
no flags Details | Diff
dmesg with the patched kernel (67.61 KB, text/plain)
2014-05-10 17:04 UTC, Téo M.
no flags Details
Fix quirk tag in video's quirk table for Dell inspiron 7520 (861 bytes, patch)
2014-05-12 05:34 UTC, Aaron Lu
no flags Details | Diff

Description Téo M. 2013-02-09 10:41:52 UTC
Description of problem:

Since the last update of the kernel, the brightness is stuck at the maximum. It can't be changed neither with keys Fn+F4/F5 nor with gnome-control-center.

Version-Release number of selected component (if applicable):

Dell Inspiron 15r "Special Edition - Blu-ray"

$ uname -r
3.7.3-101.fc17.x86_64

$ lspci |grep VGA
00:02.0 VGA compatible controller: Intel Corporation Device 0166 (rev 09)
01:00.0 VGA compatible controller: ATI Technologies Inc Device 682f


How reproducible:

Just try to change the brightness of the screen on an Dell Inspiron 15r laptop with kernel 3.7.3-101.fc17.x86_64, with keybord shortcut, or with the gnone-control-center
  
Actual results:
Nothing happens, the brightness icon appear but the brightness does not change.

Expected results:
The brightness should decrease or increase...


Additional info:

- It worked with kernel versions 3.6.x.
- It also works during boot until grub

- I am not able to make my ATI card works, so only the Intel card is used.

$ lsmod
Module                  Size  Used by
fuse                   78033  3 
ebtable_nat            12808  0 
ebtables               30758  1 ebtable_nat
ipt_MASQUERADE         12881  3 
iptable_nat            13012  1 
nf_nat_ipv4            13200  1 iptable_nat
nf_nat                 25642  3 ipt_MASQUERADE,nf_nat_ipv4,iptable_nat
xt_CHECKSUM            12550  1 
iptable_mangle         12696  1 
bridge                 91098  0 
stp                    12869  1 bridge
llc                    14046  2 stp,bridge
be2iscsi               93412  0 
iscsi_boot_sysfs       15642  1 be2iscsi
bnx2i                  54715  0 
lockd                  93438  0 
sunrpc                255581  1 lockd
cnic                   66882  1 bnx2i
uio                    19045  1 cnic
cxgb4i                 32880  0 
cxgb4                 113494  1 cxgb4i
cxgb3i                 32951  0 
cxgb3                 155602  1 cxgb3i
mdio                   13436  1 cxgb3
libcxgbi               56493  2 cxgb3i,cxgb4i
ib_iser                37806  0 
rdma_cm                42167  1 ib_iser
ib_addr                13786  1 rdma_cm
iw_cm                  18222  1 rdma_cm
ib_cm                  41726  1 rdma_cm
ib_sa                  32956  2 rdma_cm,ib_cm
ib_mad                 46341  2 ib_cm,ib_sa
ib_core                74065  6 rdma_cm,ib_cm,ib_sa,iw_cm,ib_mad,ib_iser
iscsi_tcp              18334  0 
libiscsi_tcp           24177  4 cxgb3i,cxgb4i,iscsi_tcp,libcxgbi
libiscsi               50543  8 libiscsi_tcp,bnx2i,cxgb3i,cxgb4i,be2iscsi,iscsi_tcp,ib_iser,libcxgbi
scsi_transport_iscsi    57491  8 bnx2i,be2iscsi,iscsi_tcp,ib_iser,libcxgbi,libiscsi
rfcomm                 68965  4 
bnep                   19702  2 
nf_conntrack_ipv4      14809  9 
nf_defrag_ipv4         12674  1 nf_conntrack_ipv4
ip6t_REJECT            12940  2 
nf_conntrack_ipv6      18624  8 
nf_defrag_ipv6         18206  1 nf_conntrack_ipv6
xt_state               12579  16 
nf_conntrack           84207  7 ipt_MASQUERADE,nf_nat,xt_state,nf_nat_ipv4,iptable_nat,nf_conntrack_ipv4,nf_conntrack_ipv6
ip6table_filter        12816  1 
ip6_tables             26943  1 ip6table_filter
snd_hda_codec_hdmi     36749  1 
snd_hda_codec_conexant    66455  1 
snd_hda_intel          37938  4 
snd_hda_codec         131731  3 snd_hda_codec_hdmi,snd_hda_codec_conexant,snd_hda_intel
arc4                   12616  2 
snd_hwdep              17651  1 snd_hda_codec
iwldvm                241608  0 
snd_seq                64878  0 
snd_seq_device         14137  1 snd_seq
snd_pcm                98005  4 snd_hda_codec_hdmi,snd_hda_codec,snd_hda_intel
uvcvideo               80925  0 
videobuf2_vmalloc      12968  1 uvcvideo
videobuf2_memops       13391  1 videobuf2_vmalloc
videobuf2_core         34281  1 uvcvideo
videodev              120901  2 uvcvideo,videobuf2_core
media                  20445  2 uvcvideo,videodev
snd_page_alloc         18269  2 snd_pcm,snd_hda_intel
mac80211              540054  1 iwldvm
snd_timer              28691  2 snd_pcm,snd_seq
btusb                  23871  0 
bluetooth             319586  24 bnep,btusb,rfcomm
snd                    79380  16 snd_hwdep,snd_timer,snd_hda_codec_hdmi,snd_hda_codec_conexant,snd_pcm,snd_seq,snd_hda_codec,snd_hda_intel,snd_seq_device
iwlwifi               103188  1 iwldvm
cfg80211              201717  3 iwlwifi,mac80211,iwldvm
iTCO_wdt               13481  0 
rfkill                 21737  5 cfg80211,bluetooth
mei                    75354  0 
dell_laptop            17370  0 
soundcore              14492  1 snd
iTCO_vendor_support    13420  1 iTCO_wdt
lpc_ich                17062  0 
dell_wmi               12682  0 
coretemp               13394  0 
mfd_core               13183  1 lpc_ich
microcode              23449  0 
r8169                  67601  0 
mii                    13528  1 r8169
i2c_i801               18135  0 
sparse_keymap          13527  1 dell_wmi
dcdbas                 14829  1 dell_laptop
vhost_net              33860  0 
tun                    22939  2 vhost_net
macvtap                18241  1 vhost_net
macvlan                18732  1 macvtap
kvm_intel             132720  0 
kvm                   431794  1 kvm_intel
uinput                 17615  0 
binfmt_misc            17464  1 
crc32c_intel           12902  0 
ghash_clmulni_intel    13260  0 
wmi                    18698  1 dell_wmi
i915                  567858  3 
video                  18992  1 i915
radeon                907002  0 
i2c_algo_bit           13258  2 i915,radeon
drm_kms_helper         44759  2 i915,radeon
ttm                    79761  1 radeon
drm                   264190  6 ttm,i915,drm_kms_helper,radeon
i2c_core               38354  7 drm,i915,i2c_i801,drm_kms_helper,i2c_algo_bit,radeon,videodev

Comment 1 Téo M. 2013-02-16 18:22:27 UTC
Still does not work with 3.7.6-102.fc17.x86_64

Comment 2 JAlberto 2013-03-04 21:18:40 UTC
doesn't works on 3.8.1.201 either

Comment 3 Freddy Willemsen 2013-03-13 08:02:54 UTC
Could this be the same issue as https://bugzilla.redhat.com/show_bug.cgi?id=891148 ?

Comment 4 Josh Boyer 2013-03-13 14:08:13 UTC
(In reply to comment #3)
> Could this be the same issue as
> https://bugzilla.redhat.com/show_bug.cgi?id=891148 ?

Difficult to say.  Different hardware, different GPU in use.  Probably not.

Is this still happening with 3.8.2-105.fc17 in updates-testing?

Comment 5 Freddy Willemsen 2013-03-13 16:00:47 UTC
As said in bug id 891148, Fedora 17 up to kernel 3.6 worked without issue. I have asked a colleague, he confirms brightness is working with 3.8.2-105.fc17 (nouveau and nvidia driver). So the problem (at least for me) seems to be in Fedora 18, not 17.

Comment 6 Danny Baumann 2013-03-13 16:04:39 UTC
You can read in https://bugzilla.kernel.org/show_bug.cgi?id=55071 about the root cause. The problem is in the Windows 8 code paths in the DSDT of this specific laptop; and _OSI=Windows 2012 was added in kernel 3.7.

Comment 7 Freddy Willemsen 2013-03-13 16:21:45 UTC
OK, so if I understand correctly this will be fixed in 3.9

Ah well, I can live with it for now ...

Comment 8 Danny Baumann 2013-03-13 16:36:30 UTC
Not sure where you got the impression that it will be fixed in 3.9 from?

Comment 9 Freddy Willemsen 2013-03-13 16:57:33 UTC
I may have jumped to conclusions on second glance. In my enthusiasm all I saw was "Status: RESOLVED" and "Kernel Version: 3.9-rc2".

Comment 10 Freddy Willemsen 2013-03-14 09:44:04 UTC
My colleague just informed me that when he freshly booted this morning (he updated the kernel yesterday) he can no longer change the brightness. My guess is he did not reboot into the new kernel yesterday when he reported he could still change brightness. Ergo, kernel 3.6 works, kernel 3.8 does not. Which is consistent with the remark from Danny about the addition of _OSI=Windows 2012 in kernel 3.7.

Comment 11 Josh Boyer 2013-03-14 12:53:24 UTC
I see Danny has sent a series of patches upstream now.  Hopefully those will get some review.

Comment 12 Danny Baumann 2013-03-14 13:04:55 UTC
Josh,

they're for a different problem. Basically there are a number of problems on the Inspiron 15R SE at the moment:

Without _OSI=Windows 2012:

- in-kernel brightness switching (via ACPI notifications, without user space processing XF86Brightness[Up|Down] doesn't work - this is what my patches fix
- duplicate XF86Brightness* key events (one sent by the actual keyboard, one sent by the ACPI video driver): can be fixed by adding an xorg.conf snippet that blacklists the "Video Bus" input
- if user space listens for XF86Brightness* + my patches are applied: brightness is changed multiple times (once or twice by user space through the brightness key, once by the in-kernel control): can be fixed by the module parameter video.brightness_switch_enabled=0

With _OSI=Windows 2012:
- Brightness control doesn't work at all, because the _BCM method seemingly does nothing - this is what this bug report is about. I _suspect_ it's due to the missing ASLE interrupt in that case (which is only fired in the non-W8 case), but my knowledge of the ACPI spec(s) is not good enough to tell whether it's the AML or the kernel drivers (video.ko and i915.ko are involved) that are at fault.

BTW, I seemingly can't enter a kernel parameter with spaces in grub2-efi. I tried to do acpi_osi="!Windows 2012", but no matter what kind of quoting I tried, grub2 converted the space to \x20, which made the kernel ignore the line. Can you guys reproduce that? If yes, I guess I'll write a separate report for that.

Comment 13 JAlberto 2013-04-19 16:52:38 UTC
Any progress?

Still doesn't works in 3.8.7-201.fc18.x86_64

Comment 14 Turgut Kalfaoglu 2013-04-22 20:53:14 UTC
I have the same problem on 3.8.8-202.fc18.x86_64..

xcalib works, bu the hotkeys do not.. The icon for brightness change appears when the keys are pressed, but its slider moves very little and the brightness does not change.

Comment 15 Sergio Durigan Junior 2013-06-23 08:30:52 UTC
Same thing here.  The strangest part is that this behaviour began when I upgraded the BIOS (I have a very similar machine, a Dell Inspiron 15R SE 7520, with the same video card).

I see the same thing Turgut sees: when I press the Fn+F{4,5} buttons the bar moves very little and the brightness does not change (it is important to mention that I am using gnome-settings-daemon, who is the actual responsible for changing the brightness when the buttons are pressed, on top of i3 here).  However, I can change the brightness by echoing to "/sys/class/backlight/intel_backlight/brightness".

I've been experiencing this issue in the last hour, so I don't know who is the culprit here.  Initially I thought it was gnome-settings-daemon, exactly because I managed to change the brightness via /sys.  Anyway, I'll be following this bug.  Please let me know if there is anything I can do to help.

BTW, running 3.8.13-100.fc17.x86_64 and gnome-settings-daemon-3.4.2-4.fc17.x86_64 here.

Comment 16 Sergio Durigan Junior 2013-06-23 08:37:44 UTC
From #839379, I ran "udevadm monitor" and found that the Fn+F{4,5} keys are actually changing what seems to be the wrong file:

sergio@afrodite ~ $ udevadm monitor 
monitor will print the received events for:
UDEV - the event which udev sends out after rule processing
KERNEL - the kernel uevent

KERNEL[1174.847401] change   /devices/pci0000:00/0000:00:02.0/backlight/acpi_video1 (backlight)
KERNEL[1174.848796] change   /devices/pci0000:00/0000:00:02.0/backlight/acpi_video1 (backlight)
UDEV  [1174.850755] change   /devices/pci0000:00/0000:00:02.0/backlight/acpi_video1 (backlight)
UDEV  [1174.851695] change   /devices/pci0000:00/0000:00:02.0/backlight/acpi_video1 (backlight)
KERNEL[1174.866853] change   /devices/pci0000:00/0000:00:02.0/backlight/acpi_video1 (backlight)
KERNEL[1174.867143] change   /devices/pci0000:00/0000:00:02.0/backlight/acpi_video1 (backlight)

According to my system, it should be changing "/sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight".  So yeah, maybe this is not a kernel bug (or rather not the same bug as Téo reported) after all...

Comment 17 Fedora End Of Life 2013-07-03 23:35:22 UTC
This message is a reminder that Fedora 17 is nearing its end of life.
Approximately 4 (four) weeks from now Fedora will stop maintaining
and issuing updates for Fedora 17. It is Fedora's policy to close all
bug reports from releases that are no longer maintained. At that time
this bug will be closed as WONTFIX if it remains open with a Fedora 
'version' of '17'.

Package Maintainer: If you wish for this bug to remain open because you
plan to fix it in a currently maintained version, simply change the 'version' 
to a later Fedora version prior to Fedora 17's end of life.

Bug Reporter:  Thank you for reporting this issue and we are sorry that 
we may not be able to fix it before Fedora 17 is end of life. If you 
would still like  to see this bug fixed and are able to reproduce it 
against a later version  of Fedora, you are encouraged  change the 
'version' to a later Fedora version prior to Fedora 17's end of life.

Although we aim to fix as many bugs as possible during every release's 
lifetime, sometimes those efforts are overtaken by events. Often a 
more recent Fedora release includes newer upstream software that fixes 
bugs or makes them obsolete.

Comment 18 JAlberto 2013-09-17 08:36:28 UTC
This bug is in latest kernel too: 3.10.11-200.fc19.x86_64

Comment 19 Turgut Kalfaoglu 2013-09-17 15:02:27 UTC
Indeed -- likewise for my Dell Inspiron 15R  "special edition"  as well.. The issue remains with Fedora 19 latest updates..

Comment 20 Josh Boyer 2013-09-18 20:27:57 UTC
*********** MASS BUG UPDATE **************

We apologize for the inconvenience.  There is a large number of bugs to go through and several of them have gone stale.  Due to this, we are doing a mass bug update across all of the Fedora 19 kernel bugs.

Fedora 19 has now been rebased to 3.11.1-200.fc19.  Please test this kernel update and let us know if you issue has been resolved or if it is still present with the newer kernel.

If you experience different issues, please open a new bug report for those.

Comment 21 Téo M. 2013-09-18 22:02:14 UTC
here with 3.11.1-200.fc19.x86_64, the issue is still present.

Though I have seen some related commits in the 3.12 merge window (e.g 94fb9823 in Linus's tree), I hope that will fixe it.

Comment 22 Turgut Kalfaoglu 2013-09-19 05:51:23 UTC
I just did a daily yum update which changed xorg-server, logged out and logged back in. same result.. Hitting  Fn+F4 of F5  result in the brightness icon being displayed on desktop, but no brightness change takes place.

Comment 23 Pacho Ramos 2013-09-19 06:08:41 UTC
Booting with:
acpi_osi="Linux" acpi_backlight=vendor 

as kernel parameters solved the problem with me (at least on Gentoo)

Comment 24 Turgut Kalfaoglu 2013-09-19 21:06:57 UTC
Pacho: I tried that, but I get "Oh No, something bad happened"  blurb and cannot login.

Comment 25 Téo M. 2013-12-21 10:34:35 UTC
Yippee! Backlight fixed since this morning's update (kernel 3.12.5-302.fc20.x86_64)

Thanks a lot guys!


I have now some errors at startup, but since it works, I am putting the bug at fixed. Error details below:


[root@blah ~]# systemctl status systemd-backlight
systemd-backlight - Load/Save Screen Backlight Brightness of acpi_video0
   Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static)
   Active: failed (Result: start-limit) since Sat 2013-12-21 11:24:14 CET; 1min 36s ago
     Docs: man:systemd-backlight@.service(8)
  Process: 575 ExecStart=/usr/lib/systemd/systemd-backlight load %I (code=exited, status=1/FAILURE)
 Main PID: 575 (code=exited, status=1/FAILURE)

Dec 21 11:24:14 blah systemd[1]: systemd-backlight: main process exited, code=exited, status=1/FAILURE
Dec 21 11:24:14 blah systemd[1]: Failed to start Load/Save Screen Backlight Brightness of acpi_video0.
Dec 21 11:24:14 blah systemd[1]: Unit systemd-backlight entered failed state.
Dec 21 11:24:14 blah systemd[1]: Starting Load/Save Screen Backlight Brightness of acpi_video0...
Dec 21 11:24:14 blah systemd[1]: systemd-backlight start request repeated too quickly, refusing to start.
Dec 21 11:24:14 blah systemd[1]: Failed to start Load/Save Screen Backlight Brightness of acpi_video0.



[root@blah ~]# systemctl status systemd-backlight
systemd-backlight - Load/Save Screen Backlight Brightness of acpi_video1
   Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static)
   Active: failed (Result: start-limit) since Sat 2013-12-21 11:25:16 CET; 37s ago
     Docs: man:systemd-backlight@.service(8)
  Process: 2124 ExecStart=/usr/lib/systemd/systemd-backlight load %I (code=exited, status=1/FAILURE)
 Main PID: 2124 (code=exited, status=1/FAILURE)

Dec 21 11:25:18 blah systemd[1]: Failed to start Load/Save Screen Backlight Brightness of acpi_video1.
Dec 21 11:25:18 blah systemd[1]: Starting Load/Save Screen Backlight Brightness of acpi_video1...
Dec 21 11:25:18 blah systemd[1]: systemd-backlight start request repeated too quickly, refusing to start.
Dec 21 11:25:18 blah systemd[1]: Failed to start Load/Save Screen Backlight Brightness of acpi_video1.
Dec 21 11:25:18 blah systemd[1]: Starting Load/Save Screen Backlight Brightness of acpi_video1...
Dec 21 11:25:18 blah systemd[1]: systemd-backlight start request repeated too quickly, refusing to start.
Dec 21 11:25:18 blah systemd[1]: Failed to start Load/Save Screen Backlight Brightness of acpi_video1.
Dec 21 11:25:18 blah systemd[1]: Starting Load/Save Screen Backlight Brightness of acpi_video1...
Dec 21 11:25:18 blah systemd[1]: systemd-backlight start request repeated too quickly, refusing to start.
Dec 21 11:25:18 blah systemd[1]: Failed to start Load/Save Screen Backlight Brightness of acpi_video1.

Comment 26 Téo M. 2014-05-07 17:59:54 UTC
Reopening, something is broken with Linux 3.14.2-200.fc20.x86_64

I bet that kernel's commit 0e9f81d3b7cd0649a3bc437391b6a0650f98f844 is the culprit (or at least related), though I am not able to prove it.

Comment 27 Aaron Lu 2014-05-08 04:57:58 UTC
Please list /sys/class/backlight:
$ ls /sys/class/backlight

Comment 28 Téo M. 2014-05-08 06:23:48 UTC
Here:

#ls /sys/class/backlight
acpi_video0  acpi_video1  intel_backlight

or better yet:

acpi_video0 -> ../../devices/pci0000:00/0000:00:01.0/0000:01:00.0/backlight/acpi_video0
acpi_video1 -> ../../devices/pci0000:00/0000:00:02.0/backlight/acpi_video1
intel_backlight -> ../../devices/pci0000:00/0000:00:02.0/drm/card0/card0-LVDS-1/intel_backlight

Comment 29 Aaron Lu 2014-05-08 07:19:20 UTC
(In reply to Téo M. from comment #28)
> Here:
> 
> #ls /sys/class/backlight
> acpi_video0  acpi_video1  intel_backlight

This is not expected, unless this is not a Win8 firmware.
Please attach your acpidump:
# acpidump > acpidump.txt

Also, attach your dmesg.

Thanks.

Comment 30 Téo M. 2014-05-08 12:52:07 UTC
Created attachment 893625 [details]
output of acpidump

Comment 31 Téo M. 2014-05-08 12:52:41 UTC
Created attachment 893626 [details]
output of dmesg

Comment 32 Téo M. 2014-05-08 13:33:28 UTC
(In reply to Aaron Lu from comment #29)
> (In reply to Téo M. from comment #28)
> > Here:
> > 
> > #ls /sys/class/backlight
> > acpi_video0  acpi_video1  intel_backlight
> 
> This is not expected, unless this is not a Win8 firmware.

The laptop was shipped with Win7 pre-installed IIRC, not 100% sure though. I don't know if that information helps?

Comment 33 Aaron Lu 2014-05-08 14:53:52 UTC
Does the acpi_video and/or intel_backlight work? What about the previous kernel?

Comment 34 Téo M. 2014-05-08 15:26:41 UTC
(In reply to Aaron Lu from comment #33)
> What about the previous kernel?

With kernel 3.13.10-200.fc20.x86_64, it works like a charm.

> Does the acpi_video and/or intel_backlight work? 

Please, how can I check that?

Comment 35 Aaron Lu 2014-05-09 01:21:18 UTC
(In reply to Téo M. from comment #34)
> > Does the acpi_video and/or intel_backlight work? 
> 
> Please, how can I check that?

# cd /sys/class/backlight/acpi_videoX
# cat max_brightness
XXX
# echo x > brightness
# echo y > brightness
x, y need to be smaller than max XXX.

Then do the same thing for intel_backlight, see if any backlight level changes, thanks.

Comment 36 Téo M. 2014-05-09 05:03:41 UTC
It only works with intel_backlight. Nothing happens with acpi_video0 nor 1.

Comment 37 Aaron Lu 2014-05-09 06:03:20 UTC
You dmi table please:
# dmidecode > dmi.txt

Comment 38 Téo M. 2014-05-09 16:49:51 UTC
Created attachment 894101 [details]
output or dmidecode

Comment 39 Aaron Lu 2014-05-10 07:58:42 UTC
OK, I checked the DMI table, it is Dell Inspiron 7520, which is already in video's quirk table. And the firmware also claims win8, the i915 created the raw backlight interface, so I can't tell why the acpi_video interface is still created...

Téo, I wonder if compiling kernel is OK to you? I need to add some debug prints in acpi_video_verify_backlight_support to see what's going wrong exactly.

Comment 40 Téo M. 2014-05-10 08:18:46 UTC
> Téo, I wonder if compiling kernel is OK to you? I need to add some debug
> prints in acpi_video_verify_backlight_support to see what's going wrong
> exactly.

Compiling the kernel should be OK, if I follow those instructions: https://fedoraproject.org/wiki/Building_a_custom_kernel, it will be fine right?

Tell me what debug prints you need exctly

Comment 41 Aaron Lu 2014-05-10 08:57:10 UTC
Created attachment 894218 [details]
add debug prints to verify what's going wrong

Apply on top of v3.14.2.
I never tried fedora's srpm build so I don't know, I always use a git tree. I think the patch should aply on top of fedora's v3.14.2 kernel too.

Comment 42 Téo M. 2014-05-10 17:04:07 UTC
Created attachment 894313 [details]
dmesg with the patched kernel

I attached the output of dmesg with the patched kernel. Relevant lines are all:

acpi_video_verify_backlight_support: win8=1, use_native=0, raw=1

Comment 43 Téo M. 2014-05-10 17:05:47 UTC
Ah, and I mistakenly built 3.14.3 instead of 3.14.2... I hope it's OK? I can do the same with 3.14.2 if needed.

Comment 44 Aaron Lu 2014-05-12 05:34:07 UTC
Created attachment 894549 [details]
Fix quirk tag in video's quirk table for Dell inspiron 7520

Please test this patch, apply on top of v3.14.3.
BTW, I think I've found the problem, the tag used to identify 7520 is product version in video's quirk table while it should be product name.

Comment 45 Téo M. 2014-05-12 19:40:40 UTC
Yay! The patch #894549 fixes the bug, please push. That's really nice, thanks a lot Aaron!

Comment 46 Aaron Lu 2014-05-13 15:02:14 UTC
Patch sent out:
https://patchwork.kernel.org/patch/4162111/

Comment 47 Téo M. 2014-05-21 17:22:03 UTC
The fix landed in the main tree and will be available in the next release. Closing the bug, thanks all!

commit 5ff365fb6aed4c7ee5aae7b0239ce0b514aefabc
Author: Aaron Lu <aaron.lu>
Date:   Tue May 13 09:51:50 2014 +0800

    ACPI / video: correct DMI tag for Dell Inspiron 7520
    
    The DMI tag used to identify Dell Inspiron 7520 should be product name
    instead of product version.
    
    Fixes: 0e9f81d3b7cd (ACPI / video: Add systems that should favour native bac
    Reported-and-tested-by: Téo Mazars <teomazars>
    References: https://bugzilla.redhat.com/show_bug.cgi?id=909552
    Cc: All applicable <stable.org>
    Signed-off-by: Aaron Lu <aaron.lu>
    Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki>


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