On 05/23/2015 10:07 AM, Jape Person wrote:
At some point during the recent slew of updates in testing I
noticed that one of my four systems began exhibiting a strange
behavior. When I log out from a desktop session to the greeter
or switch to a console screen, the display is so dark I can
hardly see its content. I would point out that the first time
the login screen is seen after boot it shines at normal brightness.
The affected system is a Lenovo Thinkpad T520i, the only system
among my 4 machines running the AMD64 kernel. Fortunately it has
screen brightness control built into the hardware, so remedying
the dim screens is easy enough.
I recall having to fiddle with screen brightness on in the DE
(Xfce) more than once in the past as versions of the power
manager changed. But, in those cases, the login screen and
console screen brightness were not affected.
The other odd effect I see is that using the screen brightness
keys when at the login screen or on the console doesn't step the
brightness. The first touch of the brightness control takes
brightness all the way to 100%. Once logged in, the brightness
control is properly granular.
One more oddity about brightness control on the system is that
the new power manager plugin for the Xfce panel behaves as I
would expect -- except that, if it is sitting in the
notification area instead of out on the panel, use of the mouse
scrollwheel with the cursor positioned over the power icon does
not control screen brightness.
This latter issue might well be attributed to the plugin itself,
but is the issue of login screen and console screen brightness
not a function of non-DE components?
There are many, many reports online of people having problems
with display brightness recently, but none that I have read
seems at all a close match to my situation.
Could someone here steer me toward documentation or testing
methods that could help me resolve the issue of login screen and
console brightness?
Thanks!
Additional Information:
Once the first use of the brightness key has brightened the
login screen or the console screen, the control becomes granular
when decreasing or increasing screen brightness. Each time a
brightness control keypress is made with a console screen
visible, a "^@" appears on the command line or prompt line in
addition to the change in screen brightness.
The initial adjustment to screen brightness has to be performed
separately on the login screen and one of the console screens.
(Obviously, I think, making the adjustment on one console screen
affects all console screens.)
If I adjust the brightness on a console screen, then switch to
the login screen, then switch back to the console screen, the
console screen has become dimmed again.