More advanced power savings (rev. the DPMS extension).

Jim Gettys jg at
Wed Aug 2 13:55:25 PDT 2006

On Mon, 2006-07-31 at 15:41 -0400, Alex Deucher wrote:

> Would it make sense to use the chip's built in standy timer (somehow
> linked to the DPMS timer) or just explicitly enable or disable standby
> mode when we handle DPMS events?  Some chips may have more fine
> grained control over which parts of the chip get shutdown when they
> you may want to kick in before a DPMS event (like auto-shutdown of
> FIFOs or the overlay when you aren't using it).  I suppose they could
> be done as driver specific options.

One of the features I asked for (and got) in DCON is the following:
  a register I can set to disable the LCD after a period of time.

Why did I ask for hardware for this?

Because in the meanwhile, long before the screen saver has kicked in and
blanked the screen, we'll have powered down the entire system (suspend
to RAM) while leaving the screen on with the DCON driving it, and having
to resume from RAM to just turn off the screen seemed worth the cost of
a register.  So I can have the processor off long before the screen goes
to a blank state, and not have to wake the processor to get the screen
saver to ultimately trigger.

Moral: I don't necessarily want user space to have to handle everything.
                                     - Jim

Jim Gettys
One Laptop Per Child

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