Public bug reported:
I am running PowerTOP 1.97 beta 1 on Lubuntu Precise. There are three
reported devices called "Display backlight" on my Samsung N220 with a
Pixel Qi display. I made a couple of measurements to figure out what
these devices might be:
Power est. Usage Device name
pt_bright
1.13 W 100.0% Display backlight
1.13 W 100.0% Display backlight
183 mW 28.6% Display backlight
pt_dark
1.13 W 100.0% Display backlight
220 mW 28.6% Display backlight
220 mW 0.0% Display backlight
pt_off
1.15 W 100.0% Display backlight
1.15 W 100.0% Display backlight
212 mW 28.6% Display backlight
pt_off2
1.14 W 100.0% Display backlight
211 mW 28.6% Display backlight
211 mW 0.0% Display backlight
pt_displayoff
0 mW 100.0% Display backlight
0 mW 28.6% Display backlight
0 mW 0.0% Display backlight
bright is taken with 100% display brightness, dark with the minimum the
brightness keys in Lubuntu can do (0d according to setpci on its 00-ff
scale). off is measured with the backlight completely off, set with
setpci -s 00:02.0 F4.B=00; off2 is a second measurement under the same
conditions. displayoff was done with xset dpms force off.
So it appears to me that the first "Display backlight" is the display
itself, the last one is the actual display backlight, although is still
consumes 0,2W even when switched off. The second device seems to behave
totally erratic, showing the measurement of one of the other two devices
at random. This doesn't completely hold true when running with AC power
but then there seem to be so many other issues that it almost doesn't
seem worth mentioning.
I couldn't figure out any such pattern for the usage percentage though.
Any help on how to dig deeper into this is appreciated. Also, any hints
how to really switch off the backlight would be great. Other than that,
powertop should show only existing devices and name them correctly.
Should I also report this to power [at] bughost org?
** Affects: powertop (Ubuntu)
Importance: Undecided
Status: New
** Tags: backlight battery display energy power powertop usage
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/949221
Title:
powertop incorrectly reports multiple display brightness devices to
use power
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/powertop/+bug/949221/+subscriptions
--
ubuntu-bugs mailing list
ubuntu-bugs@lists.ubuntu.com
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
