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

Jim Gettys jg at
Tue Aug 8 04:14:41 PDT 2006

On Tue, 2006-08-08 at 11:39 +0200, Egbert Eich wrote:
> Jim Gettys writes:
>  > 
>  > > Thats is a confusing thing.  In fact if the frame buffer is powered 
>  > > down, the screen will be
>  > > undefined.  i.e. not working.
>  > 
>  > This isn't true, and I'll give two counter examples:
>  >    o E-Ink displays.
>  >    o Our DCON driven display.
> Right. This discussion went well beoyond your use case.
> We looked at the default case with todays hardware.
> Here is what I have been saying all along:
> We need more input from hardware vendors what we can
> realistically expect in the future. Are E-Ink displays
> (as much as I would like to have it) something that
> is going to happen?

To some degree, yes.  E-ink has the major feature of 0 power consumption
with a stable image.  We see e-ink in a few e-book products at this date
(the Sony LIBRie being the first, and there are others out there). So
far, these are confined to e-books as e-ink doesn't refresh fast enough
to be used for arbitrary applications.  This, along with cost and volume
requirements, is why the OLPC system uses a TFT based design (though it
is a novel TFT).

Whether e-ink will be overtaken by other display technologies and/or
becomes fast enough to compete head to head with TFT remains to be seen.
What we've shown with our chip is that there are alternatives using
conventional TFT display technology with good (if not quite so perfect)
power savings.

So we now meet the criterion of more than one example (though in the
e-ink case, you have no reason to bother to turn off the screen, since
you don't get further power savings; if you blank an e-ink display, it
is because you don't want the contents viewable rather than to save

> As long as hardware vendors don't talk to us until it
> is too late ("We need to release a driver that can do 
> this and that by the end of next month") we can hardly
> react and create an infrastrucutre.

Hey, we're talking to you (us).  And e-ink has been on the market (at a
low level) for a year or two now.  I'm very aware of the situation

Now that is up and running seriously, we ( needs to
transition from reactive mode to active engagement in technology

>  > 
>  > And there are other technologies being looked at that may make the
>  > display able to be "live", which any ability to modify the image is
>  > turned off.
> Knowing that there will be a system with this feature
> being deployed (the OLPC box) should provide sufficient
> incentive to take this case into account in our design.

                             - Jim

Jim Gettys
One Laptop Per Child

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