Gentoo Forums
Gentoo Forums
Gentoo Forums
Quick Search: in
Kernel upgrade 3.15.3 -> 3.16.1 screen dimming broke
View unanswered posts
View posts from last 24 hours

 
Reply to topic    Gentoo Forums Forum Index Kernel & Hardware
View previous topic :: View next topic  
Author Message
chias
Tux's lil' helper
Tux's lil' helper


Joined: 06 Nov 2009
Posts: 77
Location: everywhere

PostPosted: Sun Aug 17, 2014 3:25 am    Post subject: Kernel upgrade 3.15.3 -> 3.16.1 screen dimming broke Reply with quote

I use XFCE, and I just updated my kernel from 3.15.3 to 3.16.1. Since updating, the screen dimming / brightening keys no longer dim the screen, which stays at full brightness (although the notice thing works, and indicates that the screen is dimming even though it isn't). The only effect the buttons do have is that when brightness gets to zero, the screen switches off entirely (which did *not* happen under 3.15.3).

The only way I've found of actually changing screen brightness is to unplug the laptop, at which point it dims to 20% brightness, but plugging it back in restores it to 100%. Booting into the 3.15.3 kernel makes the problem go away and dimming/brightening works as expected.

I configured 3.16.1 by simply copying my 3.15.3 .config file over and running "make menuconfig". Has anyone else seen this / know how to go about diagnosing what's wrong and fixing it?
Back to top
View user's profile Send private message
Sulman
n00b
n00b


Joined: 15 Feb 2014
Posts: 63

PostPosted: Sun Aug 17, 2014 11:12 pm    Post subject: Reply with quote

What's the hardware platform? Which gpu driver? I've found screen brightness hotkeys to be the one thing that periodically break whatever flavour of Linux you use.

It sounds like XFCE is recognising the keystrokes correctly but they're not driving anything anymore. Do you know what they map to? Perhaps that behaviour has changed, either in ACPI or for e.g. xbacklight.
Back to top
View user's profile Send private message
chias
Tux's lil' helper
Tux's lil' helper


Joined: 06 Nov 2009
Posts: 77
Location: everywhere

PostPosted: Sat Sep 20, 2014 10:10 am    Post subject: Reply with quote

Thanks for the tips

Hardware platform is a "Samsung ATIV book 6", and I believe I'm using the Intel graphics drivers although the laptop does also have a Radeon card.

Since this issue arose both xfce4-power-manager and the kernel have both received an upgrade, and the problem remains :( I don't know what the keys map to (I have not changed any keymappings from the defaults) and I don't have xbacklight installed.

EDIT: after installing xbacklight, I can now dim the screen by using xbacklight. The brightness keys continue to display the brightness changing notification without changing the brightness, though
Back to top
View user's profile Send private message
albright
Advocate
Advocate


Joined: 16 Nov 2003
Posts: 2541
Location: Near Toronto

PostPosted: Sat Sep 20, 2014 12:09 pm    Post subject: Reply with quote

Did you try the kernel boot parameter:

Quote:
acpi_backlight=vendor

_________________
.... there is nothing - absolutely nothing - half so much worth
doing as simply messing about with Linux ...
(apologies to Kenneth Graeme)
Back to top
View user's profile Send private message
chias
Tux's lil' helper
Tux's lil' helper


Joined: 06 Nov 2009
Posts: 77
Location: everywhere

PostPosted: Sat Sep 20, 2014 9:33 pm    Post subject: Reply with quote

Correction to my previous post: xbacklight works with the old kernel only.

Thanks for the tip about the kernel boot parameter! I just tried it though, and screen dimming still does not work. My boot parameters are:

Code:
quiet root=/dev/ram0 crypt_root=UUID=5f1018f8-8007-43ea-9032-9b1bf1abb3c8 real_root=/dev/mapper/linux-gentoo root_keydev=UUID=399F-3122 root_key=S1AXNEAD702790F_1.bin.gpg rootfstype=ext4 key_timeout=0 dolvm acpi_backlight=vendor
Back to top
View user's profile Send private message
chias
Tux's lil' helper
Tux's lil' helper


Joined: 06 Nov 2009
Posts: 77
Location: everywhere

PostPosted: Tue Sep 23, 2014 10:09 pm    Post subject: Reply with quote

So this is interesting. I had a look in '/sys/class/backlight/intel_backlight':

Code:
human intel_backlight # cat max_brightness
4648
human intel_backlight # cat brightness
4648
human intel_backlight # cat actual_brightness
4648


Then I used the screen-dimming buttons to attempt to change the brightness. The brightness-change notification came up as always, just like volume change notifications do, and then:

Code:
human intel_backlight # cat max_brightness
4648
human intel_backlight # cat brightness
472
human intel_backlight # cat actual_brightness
472


But, and here's the kicker, the actual brightness of the screen did not change. The only way I am able to change the brightness of the screen is by unplugging or plugging in my laptop: when it's plugged in it shines with the fury of a thousand suns; when it's unplugged I can hardly see a thing.

Writing to the 'brightness' file acts exactly the same as using the brightness keys: the only time anything happens is if I set a brightness value of zero, at which point the screen turns off entirely. Anything non-zero is "on", where "on" is either full-brightness if plugged in or super-dim if not plugged in.
Back to top
View user's profile Send private message
albright
Advocate
Advocate


Joined: 16 Nov 2003
Posts: 2541
Location: Near Toronto

PostPosted: Wed Sep 24, 2014 11:39 am    Post subject: Reply with quote

I'm curious if you boot from another linux distro cd or usb stick, do
the backlight keys work?
_________________
.... there is nothing - absolutely nothing - half so much worth
doing as simply messing about with Linux ...
(apologies to Kenneth Graeme)
Back to top
View user's profile Send private message
chias
Tux's lil' helper
Tux's lil' helper


Joined: 06 Nov 2009
Posts: 77
Location: everywhere

PostPosted: Wed Sep 24, 2014 10:52 pm    Post subject: Reply with quote

Good question! Just booted using an Xubuntu live-usb, and yes the brightness keys work perfectly.
Back to top
View user's profile Send private message
chias
Tux's lil' helper
Tux's lil' helper


Joined: 06 Nov 2009
Posts: 77
Location: everywhere

PostPosted: Sun Oct 05, 2014 4:54 pm    Post subject: Reply with quote

Because 100% and 1% are both fairly unusable, my current workaround is to use kernel 3.15.3 and use xbacklight to adjust the screen brightness. I'd really like to be able to update though... does anyone have any other ideas what might solve things?
Back to top
View user's profile Send private message
chias
Tux's lil' helper
Tux's lil' helper


Joined: 06 Nov 2009
Posts: 77
Location: everywhere

PostPosted: Tue Nov 11, 2014 8:04 pm    Post subject: Reply with quote

I still haven't managed to make any headway on this... does anyone have any other suggestions?
Back to top
View user's profile Send private message
Sakaki
Apprentice
Apprentice


Joined: 21 May 2014
Posts: 287

PostPosted: Wed Nov 12, 2014 1:32 am    Post subject: Reply with quote

Hi chias,

It may be that you are affected by this i915 issue?
If so, you might try setting:
Code:
video.use_native_backlight=0

in your kernel command line, and see if that fixes things.
I had a similar issue on my Panasonic CF-AX3, and setting this option resolved it.
_________________
Regards,

sakaki
Back to top
View user's profile Send private message
chias
Tux's lil' helper
Tux's lil' helper


Joined: 06 Nov 2009
Posts: 77
Location: everywhere

PostPosted: Sat Nov 22, 2014 3:11 am    Post subject: Reply with quote

Hm, that didn't seem to help either.

Further investigation though shows that this issue continues to vex me even with a fresh Debian install on the same hardware. Which says to me that it probably isn't an issue to be fixed on the Gentoo forums :<
Back to top
View user's profile Send private message
Display posts from previous:   
Reply to topic    Gentoo Forums Forum Index Kernel & Hardware All times are GMT
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum