Mailinglist Archive: radeonhd (333 mails)

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[radeonhd] [patch] preliminary R5xx PowerPlay support
  • From: "Yang Zhao" <yang@xxxxxxxxxx>
  • Date: Tue, 7 Oct 2008 20:56:44 -0700
  • Message-id: <40a7b1aa0810072056h769b09ddr9702411bb1dad7dc@xxxxxxxxxxxxxx>
Hi all,

Attached is a patch giving preliminary support for PowerPlay on r5xx
chips. What's contained has been tested only on a single M52
(Mobility Radeon X1300 in a Thinkpad T60)---I figured it was about
time I got it into more people's hands.


NO GUARANTEES ARE MADE THAT THE ADDED CODE WILL FUNCTION AS EXPECTED.
YOUR EXPERIENCE MAY VARY. VOLTAGE AND CLOCK SETTINGS ARE CHANGED BY
THE NEW CODE, AND THIS MAY BE DANGEROUS TO YOUR HARDWARE. TEST AT YOUR
OWN RISK.

DO _NOT_ ATTEMPT TO RUN ON A GPU THAT IS NOT PART OF THE R500 SERIES.


(Phew! Now that I've got that out of the way...)

The patch is against current master at time of writing: commit
0fd255dbf3a861e4192ddbc4ce8453c9b3965877.

It started as a port of agd5f's experimental PowerPlay support branch
from xf86-video-radeon, with the infrastructure necessary to support
it. Some additional bit-banging were added later to enable various
power management related features not referenced by atombios.h.

I have not tried to make sure it compiles and runs with different
compile-time configurations, and as such, both AtomBIOS and RandR
support are required. If you need to use the NoRandr option to have
reliable mode setting, this patch will most likely not work for you.


At driver start time, it will parse the AtomBIOS PowerPlay table and
automatically attempt to apply the mode marked as default. You can
override the default mode by specifying a "PowerPlayMode" option with
the desired mode number, but it is not possible to disable this
behaviour completely. You can see a dump of the PowerPlay modes
available in Xorg.log. This dump is done twice: first directly from
AtomBIOS, then again from what was collected by the driver.

The effective PowerPlay mode is exposed through the POWERPLAY RandR
property, and can be viewed and set using xrandr. This property is
available on all outputs.


As PowerPlay is not yet documented, most of the options applied were
determined through guesswork and experimentation. Again, I can't make
any assurances as to whether they will work or are even safe for your
particular hardware.

If you would like to help out, a copy of Xorg.log running on your R500
hardware would be much appreciate it, as I do not have access to any
other R500 hardware. logverbose=7 is not required.

If you are feeling particularly brave and would like to experiment, it
would be nice to find out how to properly enable MC host dynamic clock
gating support. This is the only option from my own PowerPlay table
with corresponding register settings (MC_HOST_DYN_CNTL) that I have
not been able to tweak without causing issues.


Give it a go, let me know how it goes, and try not to set anything on fire. :)

Cheers,
Yang Zhao
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