Bug 70256 - [snb] initial backlight brightness is zero
Summary: [snb] initial backlight brightness is zero
Status: CLOSED NOTOURBUG
Alias: None
Product: DRI
Classification: Unclassified
Component: DRM/Intel (show other bugs)
Version: unspecified
Hardware: Other All
: medium normal
Assignee: Intel GFX Bugs mailing list
QA Contact: Intel GFX Bugs mailing list
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2013-10-07 21:58 UTC by Kirill Tkhai
Modified: 2017-07-24 22:57 UTC (History)
3 users (show)

See Also:
i915 platform:
i915 features:


Attachments
dmesg (128.65 KB, text/plain)
2013-10-11 23:21 UTC, Kirill Tkhai
no flags Details
opregion (8.00 KB, application/octet-stream)
2013-10-11 23:22 UTC, Kirill Tkhai
no flags Details

Description Kirill Tkhai 2013-10-07 21:58:22 UTC
Hi,

I execute kernel v3.11 on HP 250 G1 notebook. There is strange behaviour. Two cases:

1)No parameters are passed to i915.

Screen is black: since grub is finished till X server is started. Brightness is 0, but it's possible to increase it by Fn keyboard keys.

In the process of powerdown everything is OK: I see all nice sysvinit messages.

2)Parameter invert_brigntness=1 is passed.

In the process of boot everything is OK: I see start messages of sysvinit services.

Going to powerdown is complitely black, but Fn keys light screen fires.

 lspci is:
 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) (prog-if 00 [VGA controller])
         Subsystem: Hewlett-Packard Company Device 1854
         Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
         Status: Cap+ 66MHz- UDF- FastB2B+ ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
         Latency: 0
         Interrupt: pin A routed to IRQ 42
         Region 0: Memory at c2000000 (64-bit, non-prefetchable) [size=4M]
         Region 2: Memory at b0000000 (64-bit, prefetchable) [size=256M]
         Region 4: I/O ports at 4000 [size=64]
         Expansion ROM at <unassigned> [disabled]
         Capabilities: [90] MSI: Enable+ Count=1/1 Maskable- 64bit-
                 Address: fee0f00c  Data: 41b1
         Capabilities: [d0] Power Management version 2
                 Flags: PMEClk- DSI+ D1- D2- AuxCurrent=0mA PME(D0-,D1-,D2-,D3hot-,D3cold-)
                 Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
         Capabilities: [a4] PCI Advanced Features
                 AFCap: TP+ FLR+
                 AFCtrl: FLR-
                 AFStatus: TP-
         Kernel driver in use: i915

Here is short discussion with Jani Nikula and Daniel Vetter: http://lists.freedesktop.org/archives/intel-gfx/2013-October/034341.html

Regards,
Kirill
Comment 1 Jani Nikula 2013-10-11 11:18:28 UTC
Boot without backlight related kernel parameters, set drm.debug=0xe module parameter, and attach dmesg all the way from early boot to the problem.

Do backlight hotkeys work? How is their polarity?

Please mount debugfs and attach /sys/kernel/debug/dri/0/i915_opregion.
Comment 2 Kirill Tkhai 2013-10-11 23:21:44 UTC
Created attachment 87492 [details]
dmesg
Comment 3 Kirill Tkhai 2013-10-11 23:22:24 UTC
Created attachment 87493 [details]
opregion
Comment 4 Kirill Tkhai 2013-10-11 23:26:32 UTC
Hotkeys work, polarity is standard. Kernel loads complitely in dark. Starting of X server does not change brightness. Hotkeys do.
Comment 5 Daniel Vetter 2013-10-14 07:16:35 UTC
Can you please check whether changing the brighetness through xrandr (with xrandr --output <output> --set Backlight <value>) and the raw interfaces in /sys/class/backlight/* also works?
Comment 6 Jani Nikula 2013-10-14 11:33:36 UTC
(In reply to comment #4)
> Hotkeys work, polarity is standard. Kernel loads complitely in dark.
> Starting of X server does not change brightness. Hotkeys do.

So if you use invert_brightness, the polarity is reversed, right?
Comment 7 Jani Nikula 2013-10-14 11:35:17 UTC
Please also see bug 70386.
Comment 8 Kirill Tkhai 2013-10-14 12:24:49 UTC
(In reply to comment #5)
> Can you please check whether changing the brighetness through xrandr (with
> xrandr --output <output> --set Backlight <value>) and the raw interfaces in
> /sys/class/backlight/* also works?

Daniel, I'll check this a little later, when I'm near the laptop.

(In reply to comment #6)
> (In reply to comment #4)
> > Hotkeys work, polarity is standard. Kernel loads complitely in dark.
> > Starting of X server does not change brightness. Hotkeys do.
> 
> So if you use invert_brightness, the polarity is reversed, right?

Everything is right. Tric from bug 70386 doesn't work for me: brightness is not remembered between reboots, I have to increase it by hotkeys every boot.
Comment 9 Jani Nikula 2013-10-14 16:26:16 UTC
(In reply to comment #8)
> (In reply to comment #5)
> > So if you use invert_brightness, the polarity is reversed, right?
> 
> Everything is right. Tric from bug 70386 doesn't work for me: brightness is
> not remembered between reboots, I have to increase it by hotkeys every boot.

What? So regardless of i915.invert_brightness setting, your brightness hotkeys work with the same, correct polarity?
Comment 10 Jani Nikula 2013-10-14 16:28:20 UTC
Also, what does 'ls /sys/class/backlight' output?
Comment 11 Kirill Tkhai 2013-10-14 17:48:21 UTC
(In reply to comment #9)
> (In reply to comment #8)
> > (In reply to comment #5)
> > > So if you use invert_brightness, the polarity is reversed, right?
> > 
> > Everything is right. Tric from bug 70386 doesn't work for me: brightness is
> > not remembered between reboots, I have to increase it by hotkeys every boot.
> 
> What? So regardless of i915.invert_brightness setting, your brightness
> hotkeys work with the same, correct polarity?

In case of i915.invert_brightness set, the polarity is reversed.

Ok, it looks like I understood invert_brightness wrong.

The real problem is that initial brightness is zero. If I boot without parameters:

$ cat /sys/class/backlight/acpi_video0/brightness
0

$ cat /sys/class/backlight/intel_backlight/brightness
0
Comment 12 Jani Nikula 2013-10-15 05:23:20 UTC
What if you try the acpi_osi="!Windows 2012" kernel parameter?
Comment 13 Jani Nikula 2013-10-15 05:24:28 UTC
(In reply to comment #12)
> What if you try the acpi_osi="!Windows 2012" kernel parameter?

Hmm, this was sandy bridge though... have you upgraded your bios? (I am not implying you should, I'm merely asking.)
Comment 14 Jani Nikula 2013-10-15 07:15:31 UTC
Another module parameter to try: video.use_bios_initial_backlight=0.
Comment 15 Kirill Tkhai 2013-10-15 09:33:44 UTC
(In reply to comment #13)
> (In reply to comment #12)
> > What if you try the acpi_osi="!Windows 2012" kernel parameter?
> 
> Hmm, this was sandy bridge though... have you upgraded your bios? (I am not
> implying you should, I'm merely asking.)

No yet. I'll try to do upgrade too.

(In reply to comment #14)
> Another module parameter to try: video.use_bios_initial_backlight=0.

Thanks a lot! This solves the problem. Initial values are maximum:

$ cat /sys/class/backlight/acpi_video0/brightness
100

$ cat /sys/class/backlight/intel_backlight/brightness
4845
Comment 16 Jani Nikula 2013-10-15 11:24:33 UTC
(In reply to comment #15)
> (In reply to comment #13)
> > Hmm, this was sandy bridge though... have you upgraded your bios? (I am not
> > implying you should, I'm merely asking.)
> 
> No yet. I'll try to do upgrade too.

Please don't. That may lead to more problems.

> (In reply to comment #14)
> > Another module parameter to try: video.use_bios_initial_backlight=0.
> 
> Thanks a lot! This solves the problem. Initial values are maximum:
> 
> $ cat /sys/class/backlight/acpi_video0/brightness
> 100
> 
> $ cat /sys/class/backlight/intel_backlight/brightness
> 4845

Cool! Closing as NOTOURBUG.

Please file a new bug on Power-Video component at the kernel.org bugzilla [1]. Reference this bug and that video.use_bios_initial_backlight=0 fixes the issue, and attach output of 'dmidecode' there.

[1] https://bugzilla.kernel.org/enter_bug.cgi?product=ACPI
Comment 17 Kirill Tkhai 2013-10-15 21:33:18 UTC
(In reply to comment #16)
> Please file a new bug on Power-Video component at the kernel.org bugzilla
> [1]. Reference this bug and that video.use_bios_initial_backlight=0 fixes
> the issue, and attach output of 'dmidecode' there.

Ok. Thanks again.


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