Laptop screen brightness keeps dropping down

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chrisonmint
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Laptop screen brightness keeps dropping down

Post by chrisonmint »

Since upgrading to 17.2 from 17.1 (I *think*) we are having problems with the Dell laptop i am using. At regular intervals, often after a user logs in, but sometimes 5-10mins after login, the brightness drops down from max to almost nothing.

I am using XFCE and the power settings are set to "never" dim the display for energy saving etc. I have checked this for all 3 users.

In the /sys/class/backlight/ folder, there are two folders;
  • dell_backlight
    intel_backlight
The laptop is a DELL Latitude, with intel integrated graphics.

The files in the intel folder (actual brightness, max_brightness) say 93
The equivalent files in the dell folder say 15.

Can I remove the dell folder?
Should i edit the dell files to have max=93?

I am guessing that the laptop is confused about the two folders and switches between them somehow...

I would appreciate some help on this! Thanks
Last edited by chrisonmint on Sat Aug 29, 2015 3:20 am, edited 1 time in total.
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Pjotr
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Re: Laptop screen bightness keeps dropping down

Post by Pjotr »

Don't remove the Dell folder; it's safer to let it be. Editing the Dell files looks like a good idea, though.... Afterwards, reboot your computer.
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chrisonmint
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Re: Laptop screen bightness keeps dropping down

Post by chrisonmint »

Pjotr wrote:Don't remove the Dell folder; it's safer to let it be. Editing the Dell files looks like a good idea, though.... Afterwards, reboot your computer.
even as root, it wont let me edit the files. Either by pico editor or echo...

Code: Select all

DELL dell_backlight # sudo echo 93 > max_brightness 
echo: write error: Input/output error
I added rw permissions to the file, so it should be editable...

Code: Select all

-rw-r--r-- 1 root root 4096 Aug 28 21:04 actual_brightness
-rw-r--r-- 1 root root 4096 Aug 28 14:17 bl_power
-rw-r--r-- 1 root root 4096 Aug 27 08:13 brightness
-rw-r--r-- 1 root root 4096 Aug 28 21:05 max_brightness
These files are in active use - if I drop the brightness down using the Fn keys, the number in the "brightness" and "actual_brightness" files drops down to 9..7 etc (The intel one never changes from 93. )
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Re: Laptop screen bightness keeps dropping down

Post by Pjotr »

OK.... Please generate an overview of your system like this:
- Launch a terminal window;
- make the terminal window full screen, to avoid chopped lines;
- copy/paste this command into the terminal:

Code: Select all

inxi -Fxz
(if you type: the letter F is a capital letter)

Press Enter.

Copy/paste the output in your next message.
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chrisonmint
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Re: Laptop screen bightness keeps dropping down

Post by chrisonmint »

Pjotr wrote:OK.... Please generate an overview of your system
Hi Pjotr, thanks for your help. After my posts yesterday, I remembered I had already dried some suggestions from @Cosmo - temporarily adding the following to the linux parameters in grub:

Code: Select all

acpi_osi=Linux acpi_backlight=vendor
I rebooted without those additions and the DELL folder has gone. Files inside the INTEL folder still all read 93 (for actucal, brightness and max). This number doesnt change when adjusting the brightness with Fn keys.

On boot (at the MDM login screen) the brightness was back down low and it stayed low after I logged in. Fn keys allowed me to bring the brightness back up to full.

My system info is as below. What would you recommend?

Code: Select all

System:    Host: DELL Kernel: 3.13.0-37-generic x86_64 (64 bit, gcc: 4.8.2) 
           Desktop: Xfce 4.12.2 (Gtk 2.24.23) Distro: Linux Mint 17.2 Rafaela
Machine:   System: Dell (portable) product: Latitude E4310 version: 0001
           Mobo: Dell model: 0T6M8G version: A00 Bios: Dell version: A02 date: 05/28/2010
CPU:       Dual core Intel Core i5 CPU M 520 (-HT-MCP-) cache: 3072 KB flags: (lm nx sse sse2 sse3 sse4_1 sse4_2 ssse3 vmx) bmips: 9575.5 
           Clock Speeds: 1: 1199.00 MHz 2: 1199.00 MHz 3: 1199.00 MHz 4: 1199.00 MHz
Graphics:  Card: Intel Core Processor Integrated Graphics Controller bus-ID: 00:02.0 
           X.Org: 1.15.1 drivers: intel (unloaded: fbdev,vesa) Resolution: 1366x768@60.0hz 
           GLX Renderer: Mesa DRI Intel Ironlake Mobile GLX Version: 2.1 Mesa 10.1.3 Direct Rendering: Yes
Audio:     Card: Intel 5 Series/3400 Series High Definition Audio driver: snd_hda_intel bus-ID: 00:1b.0 
           Sound: Advanced Linux Sound Architecture ver: k3.13.0-37-generic
Network:   Card-1: Intel Centrino Advanced-N 6200 driver: iwlwifi ver: in-tree: bus-ID: 02:00.0
           IF: wlan0 state: up mac: <filter>
           Card-2: Intel 82577LM Gigabit Network Connection driver: e1000e ver: 2.3.2-k port: 6040 bus-ID: 00:19.0
           IF: eth0 state: down mac: <filter>
Drives:    HDD Total Size: 160.0GB (9.3% used) 1: id: /dev/sda model: WDC_WD1600BEVT size: 160.0GB 
Partition: ID: / size: 143G used: 14G (11%) fs: ext4 ID: swap-1 size: 4.08GB used: 0.00GB (0%) fs: swap 
RAID:      No RAID devices detected - /proc/mdstat and md_mod kernel raid module present
Sensors:   System Temperatures: cpu: 43.0C mobo: N/A 
           Fan Speeds (in rpm): cpu: N/A 
Info:      Processes: 194 Uptime: 8 min Memory: 486.8/3753.1MB Runlevel: 2 Gcc sys: 4.8.4 
           Client: Shell (bash 4.3.11) inxi: 1.9.17
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Pjotr
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Re: Laptop screen brightness keeps dropping down

Post by Pjotr »

OK..... you can try xbacklight as startup application then:
https://sites.google.com/site/easylinux ... xbacklight
(item 6.3, right column)
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Re: Laptop screen brightness keeps dropping down

Post by mbott »

chrisonmint
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Re: Laptop screen brightness keeps dropping down

Post by chrisonmint »

mbott wrote:I'll be monitoring this. http://forums.linuxmint.com/viewtopic.php?f=49&t=202085

--
Mike
Hi Mike,

I have added the following command to my "application autostart" list in the "Session and Startup" preference tool. I havent seen it dim yet, but its too early to tell if this is a fix.

Code: Select all

xbacklight set 100
mbott
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Re: Laptop screen brightness keeps dropping down

Post by mbott »

chrisonmint wrote:
One question - did you see it happening with mint 17.1? I didnt on my Dell Latitude, ran an upgrade and have since seen the problem.
I will have to say [tentatively] yes, but I'm not 100% sure.

My Dell has become my primary system for the time being, so it will be a bit before I'm about to swap out the 15.04 Ubuntu drive and install the one with 17.2.

--
Mike
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Re: Laptop screen brightness keeps dropping down

Post by mbott »

chrisonmint wrote:
Hi Mike,

I have added the following command to my "application autostart" list in the "Session and Startup" preference tool. I havent seen it dim yet, but its too early to tell if this is a fix.

Code: Select all

xbacklight set 100
Will, I would not classify this as a true fix, but it does resolve the step of having to manually increasing the brightness after logging in. So, it's better but the initial cause is still present ... whatever it is.

--
Mike
chrisonmint
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Re: Laptop screen brightness keeps dropping down

Post by chrisonmint »

mbott wrote: Will, I would not classify this as a true fix, but it does resolve the step of having to manually increasing the brightness after logging in. So, it's better but the initial cause is still present ... whatever it is.

--
Mike
Well, I havent seen anything obvious in the log files when dimming occurs, and most annoyingly the xbacklight command has NOT helped. Xfce and the xbacklight command both think the brightness is still at 100% (the popup notification window in Xfce and running 'xbacklight -get' returns 100).

When it dims, running xbacklight -set 100 doesnt change the setting. I guess that the command thinks its already at max, so doesnt make the system call (if that makes sense).

Still looking for a resolution...
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