Proposed RandR per-CRTC DPMS requests

Keith Packard keithp at
Sun Mar 23 22:41:40 PDT 2008

On Sun, 2008-03-23 at 21:06 -0700, Keith Packard wrote:
> On the list for RandR 1.3 are per-CRTC DPMS requests. I was looking at
> gnome-power-manager today and noticed that it polls the X server (!)
> every 10 seconds to check DPMS states. I figured it would be good to
> write down at least a strawman proposal for how to fix that, along with
> whatever other DPMS-ish stuff I could think of. Comments and criticism
> are welcome as always.

Eric had a good critique, which pointed out some rather silly parts of
this plan.

Here's a simpler plan:

     1. Use the IDLETIME Sync stuff to measure idle time.
     2. Send events to the power manager when clients suspend the screen
        saver through the MIT-SCREEN-SAVER extension
     3. Add per-CRTC DPMS set/get requests
     4. Make the screen saver app also use the MIT-SCREEN-SAVER suspend
        request to suppress the built-in DPMS timers

Now the external power manager can monitor idle time and yet still know
when there are clients that do not want the screen saver to activate.
This is sufficient information for it to execute whatever policy it has
in mind.

This leaves one fairly simple question -- should we pull the
suspend/suspend-notify stuff into RandR and make them per-CRTC? That
would have the distinct advantage of allowing us to (eventually) get rid
of the MIT-SCREEN-SAVER extension, which appears otherwise entirely
worthless today.

(no, I don't have protocol proposed for this, it seems very simple to me

keith.packard at
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