[ltp] Re: Comparison: rovclock and PowerPlay

[David Abrahams]

"Matthias Redlich" <matthias.redlich@gmx.de> writes:

> Hello,
>
> I use a ThinkPad R52 with an ATI Radeon Mobility x300. I have always
> used fglrx with ATI Powerplay to save power. I am using my laptop for
> office tasks and programming only so I do not need extraordninary
> graphics.

I am in the same situation with different equipment.  I need lots of
resolution, so IBM decided I must be a gamer and stuffed too much
power into the GPU ;-)

Unfortunately, it gets really hot.  It's routinely at 70 degrees
centigrade when idling in the lowest power state.  In higher power
states, it gets really, really hot at idle unless the fan runs hard
(god help you if a 3d screensaver kicks in). And worse for me, ATI
decided not to enable any low-power states when in dual-head mode (but
read on...)

  Aside: I have to say, I don't understand the output of the following
  on my machine

    $ sudo aticonfig --set-powerstate=1
    $ aticonfig --lsp
        core/mem      [flags]
    -----------------
      1: 128/135 MHz  [low voltage]
    *    209/135 MHz  [low voltage]
      2: 324/135 MHz
      3: 398/324 MHz  [default state]

  It seems to indicate that I'm in an odd, unnumbered state we could
  call "1.5" that uses a higher core frequency than I'd get in state
  1.  If anyone knows what this means I'd love to hear it.

> Now I wonder whether rovclock or Powerplay is better for power saving
> and lower temperature (fan always-on problem). Has anybody got a
> comparison? What about temperature? Do you have other good hints to
> reduce the power consumption of your ATI card?

Well, I just tried rovclock and it hosed my display.  Haven't tried it
since.

Well, I've been playing around with ACPI and hotkeys and just
discovered some really interesting things.  Before I could use the
video hotkey I had to enable all the hotkeys with

  sudo echo 0xffff > /proc/acpi/ibm/hotkey

(stuck it in my /etc/rc.local actually).  Without customizing the
event response, /etc/acpi/events/ibm-videobtn was just a do-nothing
stub, but the button actually did lots: it would cycle through all
combinations of screens I had connected.  Brilliant!

I added a script that subsequently sets the GPU powerstate to 1
whenever there is only one monitor enabled.  And *then* I noticed that
when I cycled back into dual-head mode, I was still in the lowest
power state!  Not only that, but as I've been working in this state,
the GPU is the coolest I've ever seen it (67 degrees at times, though
it /is/ a cool day).

So now I'm pretty happy ;-)

Remaining complaints:

1. 67 still seems too hot for idling in the lowest power state, but
   I'm going to deal with IBM on that one.  Once my on-site service
   kicks in I might get a mobo replacement to see if it helps.

2. I'm not sure if I can control the relative order of the displays.
   I just changed it to horizontal,reverse in my xorg.conf and will
   report back whether that helps with the dynamic switching.
   However, a single
   
     aticonfig --swap

   is enough to handle that problem, and fglrx remembers the order for
   the rest of my session.
   
3. When cycling through screen configurations, the hotkey orders the
   states so that the laptop LCD is the last single screen that's on
   before it goes into dual head mode.  As a result, my gnome panels
   are on the little screen, where I don't want them, and have to be
   dragged over by hand.  Unlike the workaround for #2, that isn't
   sticky.  However, the xorg.conf change mentioned in #2 might affect
   this too.  Will report back.

4. I don't know a way to force the driver into this low-power,
   dual-head state under software control.

I hope this info is useful to someone!  Will keep poking away at this
and other issues until I have the highly usable laptop I've been
dreaming of ;-)

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com