Powersaving Monitor (DPMS)

Jason Burrell (jburrell@crl.crl.com)
Wed, 25 Dec 1996 03:10:49 -0600 (CST)


On Sat, 21 Dec 1996, Bryn Paul Arnold Jones wrote:

>
> On Fri, 20 Dec 1996, Charlie Ross wrote:
>
> >
> >
> > I have a couple questions... and theyre all kernel related :)
> >
> > 1) Is there any plan to inorporate the MAC HFS fs into the kernel source?
> >
> > 2) Powersaving monitors... I dunno if anyone else has this "problem" but i
> > figure i'd ask...
> > I have a powersaving monitor... it has 2 seperate "low power" standby
> > modes... the first is triggerd by loosing one of the syncs (I think its
> > Vsync) and the other mode is triggered by loosing BOTH syncs. Currently
> > the kernel supports my first mode but not the second... Its not that I need
> > to save power... but I'd like to minimize heat. My monitor BAKES when its
> > on... simmers when in mode 1 and is cool in mode 2. My room is hot. help
> > me?
> >
>
> Hmm, the kernel supports everything. I assume you are using the util in
> linux/drivers/char/vesa_blank.c (go cut it out if your not).
>
> # vesa_blank
> usage: setvesablank on|vsync|hsync|powerdown|off
>
> well I think that gives enough control, don't you think ....

I bought myself a monitor like Charlie describes for Christmas. The thing
is designed to be turned off in software. This actually works fine for me,
since I never turn off my computer anyway. I do, however, want the system
to shutdown the monitor. Of course, the monitor has a power switch, but I
don't really like reaching behind it all the time, and besides, the
blinking lights when in standby mode look cool. ;)

What I want is for the VC screen blanker to pop my monitor into standby
mode when it blanks the screen, and perhaps turn it "off" after 20
minutes. Then, when activity wakes the VC blanker up and it releases its
blank, it turns the monitor back on.

I went into linux/drivers/char/vesa_blank.c, snipped the utility, and
tried to use it to perform the various functions. Nada. Nothing. I've
tried with APM enabled and disabled in the CMOS, and compiled the kernel
with and without APM support. If I have APM support compiled into the
kernel and APM support enabled in the CMOS, the Linux boot hoses with a
General Protection 000, and a message about the kernel stack.

I know the functions work with the hardware I have because Windoze 95 uses
them fine. The "suspend" option on the start menu suspends the machine,
and then, about two seconds later, drops the monitor into one of its
standby modes. I'm rather curious as to why Linux hoses the boot when APM
is enabled in the CMOS, too.

I'm perfectly willing to start hacking the kernel to get this to work like
it should, and willing to hack the VC screen blanker to behave as I
described, provided it's needed and that someone will point me towards the
DPMS spec.