display brightness & slider follows hw keys or mousing, but jumps about & brightness flickers at low end

Bug #1660438 reported by kevin gunn on 2017-01-30
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Canonical System Image
Stephen M. Webb
repowerd (Ubuntu)
Alexandros Frantzis
unity8 (Ubuntu)

Bug Description

using unity8 deb session, zesty

to reproduce, reveal the "battery" indicator panel on a pc with brightness hw keys.

play around intermittently with decreasing/increasing brightness with the hw keys.
Then attempt to increase/decrease brightness with the slider.
It becomes especially interesting when the slider & actual brightness are at their max/mins.

fwiw, i was using an older dell studio laptop.

kevin gunn (kgunn72) on 2017-01-30
Changed in repowerd (Ubuntu):
assignee: nobody → Alexandros Frantzis (afrantzis)
Changed in unity8 (Ubuntu):
assignee: nobody → Lukáš Tinkl (lukas-kde)
Changed in canonical-devices-system-image:
assignee: nobody → Michał Sawicz (saviq)
Alexandros Frantzis (afrantzis) wrote :

Kevin, I can't reproduce this issue on an older dell latitude laptop. When pressing the brightness hardware keys (actually Fn + up/down arrow) the brightness slider moves accordingly, and then moving the slider correctly changes the brightness.

Note that I am running zesty with a locally fixed systemd package (see bug 1661568). I wonder if what you are seeing is a side-effect of the aforementioned systemd issue.

My proposal is to try again in a few days, when the fixed systemd package will have landed to zesty (hopefully). If the problem persists we can investigate further.

Changed in repowerd (Ubuntu):
status: New → Incomplete
kevin gunn (kgunn72) on 2017-02-22
tags: added: unity8
kevin gunn (kgunn72) wrote :

ok, this bug has evolved
to repro:
reveal the indicator panel for battery/brightness
either select drag element with mouse or choose up/down with hw brightness keys
the slider position will not respond precisely, jump about & at the extremes (max/min) settings there will be flicker between what seems to be 2 different settings

summary: - display brightness & slider follows hw keys, but brightness does not
- follow slider unity8 zesty
+ display brightness & slider follows hw keys or mousing, but jumps about
+ & brightness flickers at low end
Changed in canonical-devices-system-image:
importance: Undecided → High
Changed in repowerd (Ubuntu):
importance: Undecided → High
Changed in unity8 (Ubuntu):
importance: Undecided → High
kevin gunn (kgunn72) wrote :

added a log per request look for "kg marker" i made sure to go to the minimum and keep pressing minimum and got the flicker.

The file also has all the other scenarios i saw earlier before the "kg marker"

And i also noticed that it's constantly spewing
back to back...like every second or so. definitely not optimal.

kevin gunn (kgunn72) wrote :

also, just noticed, if i rapidly hit hw key, i get the odd flicker between settings...if i go very slow, i don't get the flicker.

kevin gunn (kgunn72) on 2017-03-02
tags: added: unity8-desktop
Changed in repowerd (Ubuntu):
status: Incomplete → Triaged
kevin gunn (kgunn72) on 2017-03-06
Changed in canonical-devices-system-image:
milestone: none → u8c-1
Michał Sawicz (saviq) wrote :

I can't see anything wrong happening with brightness on my laptop. Even playing real hard with the slider, the most I get is some lag and the slider catching up to my moves a second after I release the slider.

With buttons, everything is fine here.

I really don't see anything unity8 could be doing wrong.

Changed in unity8 (Ubuntu):
status: New → Invalid
assignee: Lukáš Tinkl (lukas-kde) → nobody
Changed in canonical-devices-system-image:
assignee: Michał Sawicz (saviq) → Stephen M. Webb (bregma)
Pat McGowan (pat-mcgowan) wrote :

I see some jitter when using the slider but it always corrects.
The hardware key shows no issue.
Samsung laptop, zesty

Changed in canonical-devices-system-image:
milestone: u8c-1 → u8c-2
status: New → Confirmed
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