[SOLVED] screen brightness too low when switching tty

bdantas · 2014-08-13 18:09:27

I have autologin enabled in LightDM, so when I boot I am taken to my MATE desktop automatically. This happens in the default tty (tty1).

Sometimes I want to switch to a different virtual terminal (e.g., by pressing Control+Alt+F2) without ending my session in tty1. However, most of the time when I do this I find that the brightness in the new tty (e.g., tty2) is so low that I can hardly see the login prompt. When I switch back to tty1 the brightness in the X session is fine. Switching back to tty2 I see that it is still dim. Hitting either the brightness-up or the brightness-down (!?) key on the laptop causes the brightness in tty2 to jump to normal.

Does anyone know how to fix this so that when I switch to a different tty the brightness is at a reasonable level right away? I am on a Lenovo Thinkpad T520 (no Nvidia, just integrated Intel graphics) in case it matters.

Last edited by bdantas (2014-08-19 17:53:05)

jasonwryan · 2014-08-13 18:19:46

Kernel version?

bdantas · 2014-08-13 18:22:09

3.14.15-1-lts

I observed the same behavior with the default kernel.

jasonwryan · 2014-08-13 18:23:32

I saw this immediately before the 3.16 kernels (the last two anyway, IIRC)...

bdantas · 2014-08-13 18:34:26

I just checked and my non-lts kernel is 3.15.7-1. I upgrade monthly on the 1st of the month.

So you are saying that the problem is likely kernel-related an may be resolved with kernel >= 3.16? If so, I hope the kernel developers backport the fix to the lts kernel--I like the idea of enhanced stability with the lts kernel (not that I ever had stability issues with the regular kernel) and don't want to switch back to non-lts just because of this.

Last edited by bdantas (2014-08-13 18:36:21)

jasonwryan · 2014-08-13 19:10:14

I'm not certain that it is kernel related, but my experience of the issue was correlated to that kernel span. You could always look through the bug tracker to see if it is a known issue.

bdantas · 2014-08-13 19:14:39

I upgraded the kernel to 3.16.0-2 and the problem is still there.

Last edited by bdantas (2014-08-14 18:45:50)

lilydjwg · 2014-08-17 03:21:41

I'm using 3.16.1 and have this problem. Before I used 3.14 and didn't have this problem. But there are a lot of packages upgraded so I'm not sure if it's a kernel problem.

bdantas · 2014-08-19 16:16:01

As an experiment, I logged in to non-graphic mode in tty1 (by adding "systemd.unit=multi-user.target" to grub2's kernel line), then tried switching ttys. No brightness problems!

As another experiment, I allowed regular boot to my desktop in tty1 (LightDM -> MATE autologin) but then got out of graphical mode by opening a terminal emulator and typing "sudo systemctl isolate multi-user.target". Once I had a cli in tty1 I then tried switching ttys. Again, no brightness problems.

I can conclude that when switching tty's, the new tty is too dim only if I have a graphical session running in tty1. Therefore, I don't think this is a kernel problem. Seems that something related to lightDM or X or MATE running in tty1 is causing the problem.

Scimmia · 2014-08-19 16:24:47

This is a bug in the intel drivers. There is a bug report on it in the Arch bugtracker.

bdantas · 2014-08-19 16:33:07

Which bug report is it? When I search the bugtracker for intel or i915 I do not see an obvious match.

Last edited by bdantas (2014-08-19 16:34:43)

Scimmia · 2014-08-19 16:38:30

https://bugs.archlinux.org/task/41353
https://bugs.archlinux.org/task/41390
http://cgit.freedesktop.org/xorg/driver … 0d681c171e

bdantas · 2014-08-19 16:48:21

The first link describes the problem well. I googled this ad nauseam and the bug report was never a hit for some reason.

Bummer, I guess there is nothing to do but wait. Still good to know, so thank you.

Last edited by bdantas (2014-08-19 17:00:41)

jasonwryan · 2014-08-19 17:16:15

Please remember to mark your thread as [Solved] by editing your first post and prepending it to the title.

bdantas · 2014-08-19 17:52:49

I marked it as solved--even though technically the problem will not be solved until the upstream bug in xf86-video-intel is fixed.

Last edited by bdantas (2014-08-19 17:55:01)

Arch Linux

#1 2014-08-13 18:09:27

[SOLVED] screen brightness too low when switching tty

#2 2014-08-13 18:19:46

Re: [SOLVED] screen brightness too low when switching tty

#3 2014-08-13 18:22:09

Re: [SOLVED] screen brightness too low when switching tty

#4 2014-08-13 18:23:32

Re: [SOLVED] screen brightness too low when switching tty

#5 2014-08-13 18:34:26

Re: [SOLVED] screen brightness too low when switching tty

#6 2014-08-13 19:10:14

Re: [SOLVED] screen brightness too low when switching tty

#7 2014-08-13 19:14:39

Re: [SOLVED] screen brightness too low when switching tty

#8 2014-08-17 03:21:41

Re: [SOLVED] screen brightness too low when switching tty

#9 2014-08-19 16:16:01

Re: [SOLVED] screen brightness too low when switching tty

#10 2014-08-19 16:24:47

Re: [SOLVED] screen brightness too low when switching tty

#11 2014-08-19 16:33:07

Re: [SOLVED] screen brightness too low when switching tty

#12 2014-08-19 16:38:30

Re: [SOLVED] screen brightness too low when switching tty

#13 2014-08-19 16:48:21

Re: [SOLVED] screen brightness too low when switching tty

#14 2014-08-19 17:16:15

Re: [SOLVED] screen brightness too low when switching tty

#15 2014-08-19 17:52:49

Re: [SOLVED] screen brightness too low when switching tty

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