RandR 1.3 additions?

[Alex Deucher]

On 7/17/07, Jerome Glisse <j.glisse at gmail.com> wrote:
> On 7/17/07, Nicolas Trangez <eikke at eikke.com> wrote:
> > On Tue, 2007-07-17 at 03:44 +0200, Jerome Glisse wrote:
> > > Talking of power management i have been wondering if it wouldn't be
> > > nice
> > > to have some kind of infrastructure to scale down GPU & VRAM clock
> > > (on card which can) anytime we don't have activity. The tricky point
> > > is that
> > > is bit hard to find out what we can call activity maybe we should just
> > > provide
> > > infrastructure and let a user program/daemon choose what is inactivity
> > > (no
> > > input in last minute, or nothing got refreshed, maybe better
> > > information is how
> > > many change happen to the currently displayed framebuffer things like
> > > damage
> > > extension might provide such information in more or less accurate
> > > way).
> > Providing infrastructure would be great, policy would go into something
> > like gnome-volume-manager I guess, which could e.g. go into low-power
> > mode when the session screensaver starts, or when the display goes into
> > DPMS mode, when the battery reaches 10%,... This fits pretty well into
> > HAL's power management methods.
> >
> > Nicolas
>
> I think we could save lot power by downclocking gpu & ram anytimes there
> is not much activity on screen this why i have though about damage extension
> to provide information on how much the screen change. If there is only the
> cursor or slow refresh things you don't want to have gpu going at 400Mhz,
> 200MHz should be more than enough. The things is that i would like to avoid
> using a daemon which query damage extension in order to set gpu clock.
> I guess it would require to add some new extension which report to a daemon
> anytime there is a major change in graphics activity, we might also want to
> avoid downclocking and upclocking the gpu every second.
>
> Anyway i guess for a first step providing infrastructure to change GPU clock
> and VRAM clock (or any other power saving things the card can offer) would
> be the first step. Then we could think to add more cleverness either by
> adding new things to damage or by adding a new extension which can take
> advantage of damage information. Btw i don't know much about damage
> extension so maybe i am wrong when thinking that it could provide
> usefull information on how much graphics activity we got.

This is starting to move into the chips control domain.  Many newer
GPUs already scale their clocks, voltage, etc. or toggle special power
modes automatically without user space intervention.

Alex