Should green_saver.ko shut off a laptop's backlight?

John Baldwin jhb at
Mon Nov 29 21:14:26 UTC 2010

On Monday, November 29, 2010 4:10:02 pm Doug Barton wrote:
> On 11/29/2010 07:09, John Baldwin wrote:
> > On Saturday, November 27, 2010 11:30:56 pm Adam Vande More wrote:
> >> On Sat, Nov 27, 2010 at 6:39 PM, Doug Barton<dougb at>  wrote:
> >>
> >>> My recollection is that green_saver should turn off an LCD backlight, but I
> >>> just loaded it up on my laptop and it's not doing so. It does remove the
> >>> text from the screen, but the backlight is still on (i.e., it is doing
> >>> exactly what blank_saver does).
> >>>
> >>> When running X DPMS works on that same laptop, so I know the hardware is
> >>> capable. This is 9-current amd64 at r214025. Any suggestions are welcome.
> >>>
> >>
> >> It's never worked for me either and this has been around awhile.
> >>
> >>
> >
> > green_saver just ask's your video card's BIOS to shut the screen off.  If the
> > BIOS doesn't turn off the backlight, that is the BIOS's problem, not
> > something we can fix.
> Ok, so does the attached seem reasonable?

I would say 'If the monitor and the video card's BIOS support it' because
both things have to be true for green_saver to work.  and/or implies that
only one has to be true.  I'm not sure the second paragraph is truly needed
since I've seen it work fine with LCD's on other laptops and other external
monitors as well.  I think simply adding the text about the video card's
BIOS is sufficient (and a definite improvement).

John Baldwin

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