On Sun, Oct 17, 2010 at 03:25:09PM -0400, Alex Deucher wrote:
On Sun, Oct 17, 2010 at 9:07 AM, Pasi Kärkkäinen pasik@iki.fi wrote:
Hello,
While I was discussing the laptop lid/dock issues with Fedora people this issue was brought up.
How do you determine if a display is actually powered on or not?
Scenario:
- Laptop in a docking station, lid open, so internal LVDS enabled.
- External DVI display connected, but powered off.
So in this case the external display shouldn't be used, since it's off.
What happens is this:
# cat /sys/class/drm/card0-DVI-D-1/status connected
# cat /sys/class/drm/card0-DVI-D-1/enabled enabled
# cat /sys/class/drm/card0-DVI-D-1/modes 1920x1080 1600x1200 1680x1050 1280x1024 1440x900 1280x960 1280x800 1024x768 800x600 800x600 640x480
So it *looks* like it's enabled and active, but actually it's powered off. Is there a method to determine the actual state?
Unfortunately not. Monitors are designed to keep the EDID powered up even if the monitor is powered off so that graphics chips can detect that something is attached. There's no way to know whether the monitor is on of off however.
Ok. Understood.
And there are no other protocols that would reply only when the monitor is actually on? :)
-- Pasi
Alex
That is pretty important information for the daemon/tool/script implementing the "policy" of which outputs to enable/disable..
Thanks!
-- Pasi
dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel
dri-devel mailing list dri-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/dri-devel