Mailinglist Archive: radeonhd (333 mails)

["Alex Deucher" <alexdeucher@xxxxxxxxx>]

On Wed, Oct 8, 2008 at 2:46 PM, Yang Zhao <yang@xxxxxxxxxx> wrote:
> 2008/10/8 Rafał Miłecki <zajec5@xxxxxxxxx>:
> > Did you compare power consumption with and without patch?
>
> I gathered some numbers through ACPI battery state, but I frankly
> don't trust it.
>
> On my T60, no wireless, lowest brightness, and CPU at lowest stepping
> mode yielded ~15W with stock radeonhd. Switching on PowerPlay dropped
> this number slightly, but I personally don't consider it statistically
> significant. Manually switching to mode 0, which down-clocks GPU and
> memory as low as it will go, gives 0.5 to 0.8W of saving.
>
> It seems that the hardware already initializes to a fairly efficient
> state, at least for me, regardless of PowerPlay.

Many laptop bioses enable basic power saving stuff by default.  There
are atom command tables to do this:
DynamicClockGating
EnableASIC_StaticPwrMgt
Take a look at the radeon driver to see how to use them.

> As I understand it, dynamic clock gating of the memory controller
> block and dynamic voltage drop can yield more, but these areas are
> proving problematic.

Much of the clock gating stuff is handled by the tables I mentioned
above.  The voltage stuff involves gpio twiddling and can be
problematic, I haven't really had a chance to play with that in depth
yet.

> > How hard will it be to introduce R600/R700 support in your patch?
>
> I've been told PowerPlay was changed entirely for R600, so it's hard
> to say until they give us those headers. In any case, the AtomBIOS
> portion will most likely just work, or do nothing; the existing
> bit-banging parts won't affect and can't be re-sued for R600+
> PowerPlay at all.

The r6xx and newer powerplay bits got a lot more complex and the
necessary bits are no longer int atombios.h.

Alex
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