Detecting screen disconnection

Benjamin Herrenschmidt benh at
Sun Oct 31 19:54:49 PST 2004

On Sun, 2004-10-31 at 16:44 +0100, Luc Verhaegen wrote:

> It would be nice to have so that one can reattach a new monitor without 
> restarting X entirely (when there are bandwidth/frequency issues). X can 
> then revalidate modes and switchmode to get a usable display again. Or 
> attach a TV and see X initialise it, while reinitialising crt. That sort 
> of thing. From what i can see, it is not that hard a task. 
> Polling all outputs all the time would be dreadful though (i'm not sure 
> if many CRT dacs can tell you if there is anything attached, dcc might 
> be an option then). Maybe a switchmode event could trigger it, maybe 
> some sort of keycombination, xrandr too, even though it's use might be 
> limited if your crt is unable to display the mode :).

It would be nice indeed if X had the capability to dynamically
add/remove displays ...

I noticed that MacOS re-triggers a detection on wakeup from sleep (maybe
we could do it in Resume() too ?) or via an explicit clic to a certain
button in a control panel.

I don't know/think we can extend easily the X protocol to send such a
message to the driver, though maybe one of the existing extensions can
be tweaked for that... Or we could have an X magic key combo triggering
an optional hook in drivers that does re-probing...


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