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orange-kao
Blue Screen Again
Posts: 4
Registered: ‎08-03-2018
Location: AU
Views: 677
Message 1 of 1

X280 screen brightness fluctuates occasionally in Ubuntu 18.04

Hello.

 

I have bought X280 one month ago and the screen brightness fluctuates occasionally, about once every 2~4 hours, for a duration of 10~20 seconds. When it happens, the brightness level fluctuates for around 1~2% at a frequency of change around 10 times per second. This issue is more likely (but not always) to happen after waking up from suspend mode, and happens almost every day.

 

I use lowest (1 out of 1515) or second lowest level of brightness (76 out of 1515 in /sys/class/backlight/intel_backlight/brightness) by pressing Fn+F5/F6 on X280. My previous machine, X201s, can run on a similar level of brightness without any issue.

 

After doing some experiment, I found that reduce the brightness to 0 (backlight off), and increase to 1 (out of 1515), can reproduce this issue easily.

 

Just wonder does there anyone running Linux and experienced the similar issue? Is it more likely a hardware design limitation, or a hardware failure?

 

Note: Contacted Lenovo via online chat, unfortunately they cannot provide useful information because I'm not running Windows. Searched online but didn't find similar issue on X280.

 

Thank you.


Details as below:

  • Screen brightness: lowest (1 out of 1515) or second lowest (76 out of 1515 in /sys/class/backlight/intel_backlight/brightness )
  • OS: Ubuntu Desktop 18.04 LTS
  • ThinkShutter: webcam covered
  • Power supply: This issue can be reproduced with or without the power supply connected. I'm using 45W PSU come with the machine.
  • Other device(s) connected: none. It is possible to reproduce this issue while there is no USB device nor HDMI screen is connected.
  • Wi-Fi: This issue can be reproduced no matter it's associated with AP or not.

 

Firmware version as below

  • BIOS 1.16 (N20ET31W)
  • EC 1.05 (N20HT18W)
  • ME 11.8.50.3460 (N20RG10W)

 

SMBIOS type 1 information as below

Manufacturer: LENOVO
Product Name: 20KFS05Q00
Version: ThinkPad X280
SKU Number: LENOVO_MT_20KF_BU_Think_FM_ThinkPad X280
Family: ThinkPad X280

 

 

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