I'm building several wall mounted kiosk that will be placed in remote locations and i'm trying to find a way to build in some longevity / power saving options (IE put them to sleep when the location is outside of operating hours).
I'm running the standard raspbian wheezy image on them.
Currently what I have working is running
xset dpms force off to disable it and
xset dpms force on && xset s reset && xset s off && xset -dpms $$ xset s noblank to wake it back up and disable the blanking again (it resets to the default of going to sleep after 10 minutes after forcing it on / off).
I was hoping to be able to put the display (a Westinghouse 32" HDTV connected over HDMI) to sleep with
tvservice -o which works with one small problem. I'm powering the Pi off of the TV USB port and when the monitor goes to sleep power is cut to the Pi so that won't really work.
I could tell the location personnel to power off and on the tv when they open and close which would in-turn cut power to the Pi; while I've yet to have any problems with hard power-offs like that, I don't really want to make that the standard operating model for units that would require two day shipping of a new drive to restore should something happen to them. Having it truly offline through the night also means I can not push large video content to them over night and in general introduces new problems with the potential of it being powered off in the middle of receiving a large content update (I do have protections build in to the process by which it checks in for new content to recover from this but again, would prefer to minimize the potential problems this could introduce).
I'm mostly happy with the dpms setting method with the exception that the backlight stays on. I attempted to install and use
xbacklight -set 0 to dim the display but it reports that there are no configurable displays detected.
The man page for xbacklight indicates that it only supports particular video cards and that you may want to look for a card specific utility to handle this issue.
Does such a utility exist for the Raspberry Pi's video card specifically?