[Intel-gfx] [PATCH] add LVDS downclocking support
erik.andren at gmail.com
Fri Aug 7 11:35:36 PDT 2009
2009/8/7 Jesse Barnes <jbarnes at virtuousgeek.org>:
> On Mon, 23 Mar 2009 00:30:11 +0000
> Steven J Newbury <steve at snewbury.org.uk> wrote:
>> On Sun, 2009-03-22 at 20:18 +0100, Erik Andrén wrote:
>> > -----BEGIN PGP SIGNED MESSAGE-----
>> > Hash: SHA1
>> > Jesse Barnes wrote:
>> > > This is a refreshed patch from Matthew Garrett to enable LVDS
>> > > downclocking. 965+ hardware can do this automatically, but other
>> > > 9xx chips need some help. So this patch adds some damage code to
>> > > track idle time. If we're idle for more than 500ms we downclock
>> > > the display based on the value calculated at mode set time.
>> > >
>> > > Comments & testing appreciated. I've only tested on my GM45 so
>> > > far, and I think to fully realize the benefits we'll need to
>> > > enable self refresh, but it should help on many platforms as-is.
>> > >
>> > Hi,
>> > I've tested this on my 965GM laptop applied on top of Ubuntu Jauntys
>> > 2.6.3 version of the intel driver. When measuring with my Energy
>> > Monitor 3000  I did not record any power savings at all. In fact,
>> > I saw an increase of a couple of deciwatts. (Could be a measuring
>> > error though).
>> > Otherwise the system seemed stable and functioned as expected.
>> > What is the expected power decrease when using this patch?
>> > Best regards,
>> > Erik Andrén
>> > 
>> > http://www.alamaison.com.au/p/361923/voltcraft-plus-energy-monitor-3000.html
>> I'm not surprised you didn't see any change measuring power usage at
>> the outlet. Laptop power supplies are rarely switched mode, and
>> typically provide their full rating while in use. They aren't
>> typically designed with energy efficiency in mind.
>> If you want to measure the energy efficiency of a laptop, your best
>> bet is powertop when running from battery.
> Have you guys had a chance to test the latest patchset from Matthew and
> myself? Seems to save quite a bit of power on my GM45 and 915GM test
What are the software requirements to test these patches out?
> Jesse Barnes, Intel Open Source Technology Center
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