Fixed display power management

[Tichun]

Due to Raspberry Pi's peculiarity, default linux DPMS doesn't turn the screen off after idle time, it only fills it with a dark color.
That is solved when using the unfinished OpenGL driver. But that isn't the only way!

Minimal C code

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#include <X11/extensions/scrnsaver.h>
#include <stdio.h>

int main(void) {
    Display *dpy = XOpenDisplay(NULL);

    if (!dpy) {
        return(1);
    }

    XScreenSaverInfo *info = XScreenSaverAllocInfo();
    XScreenSaverQueryInfo(dpy, DefaultRootWindow(dpy), info);
    printf("%u\n", info->idle);

        return(0);
}

And a script to make it all work

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#!/bin/bash
idle=false
idleAfter=480000
while true; do
          idleTimeMillis=$(./getIdle)
              if [[ $idle = false && $idleTimeMillis -gt $idleAfter ]] ; then
                              idle=true
                              vcgencmd display_power 0
                fi

	if [[ $idle = true && $idleTimeMillis -lt $idleAfter ]] ; then
		idle=false
		vcgencmd display_power 1
	fi
                sleep 4      # polling interval
                done

Source of information

I hope something like this gets into Raspbian.

[klricks]

Adding this to /boot/config.txt will automatically turn off video output on blanking timeout.

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hdmi_blanking=1

On blanking my TV will show no signal message for about 20 min then turn off. Once the screen has gone off it won't wake up again unless I press the ON button. While the no signal message is displayed the RPi screen will wake up as expected.

I also get the same behavior when using vcgencmd display_power 0 from command line.... After the 20 min screen off, issuing vcgencmd display_power 1 will not turn on the display without also pressing the power ON button. (Tested by VNC connection).