[Bug 42854] Power management doesn't work on dualhead

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=42854

nautsch <nautsch2 at googlemail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
         Resolution|NOTABUG                     |

--- Comment #3 from nautsch <nautsch2 at googlemail.com> 2012-09-10 10:17:49 UTC ---
Hi.

I just found this bug and I wanted to add my 2 cents here and reopen it.

The Windows driver manages to stay underclocked in a dual head setup and so
seems the fglrx driver (which somehow kills 2D performance and is therefore not
an option).

I see, that this bug is almost a year old, but for me this is a real issue,
which does not occur in a Windows environment. The fans ramp up due to the
additional heat, and the clocks don't even drop a little, but stay at the
default speed.

This has to be adressable in some way. I don't think, that a second head needs
a 9 times higher frequency (and 15 degrees Celsius more) on both GPU and VRAM
than one head does.

I am on an HD6870 with the following setup:

# xrandr 
Screen 0: minimum 320 x 200, current 4480 x 1440, maximum 16384 x 16384
DVI-0 connected 2560x1440+1920+0 (normal left inverted right x axis y axis)
597mm x 336mm
   2560x1440      60.0*+
 --- snip ---
DisplayPort-0 disconnected (normal left inverted right x axis y axis)
DisplayPort-1 disconnected (normal left inverted right x axis y axis)
HDMI-0 connected 1920x1200+0+240 (normal left inverted right x axis y axis)
518mm x 324mm
   1920x1200      60.0*+
 --- snip ---

Both monitors are connected via DVI, which make the HDMI-0 name a little
misleading.

These are the clocks on dual head:
# cat /sys/kernel/debug/dri/0/radeon_pm_info 
default engine clock: 915000 kHz
current engine clock: 914940 kHz
default memory clock: 1050000 kHz
current memory clock: 1050000 kHz
voltage: 1200 mV

and these on single head (just deactivated HDMI-0 with xrandr --output HDMI-0
--off):
# cat /sys/kernel/debug/dri/0/radeon_pm_info 
default engine clock: 915000 kHz
current engine clock: 99990 kHz
default memory clock: 1050000 kHz
current memory clock: 150000 kHz
voltage: 1200 mV

power_profile is set to "low" and power_method obviously to "profile". dynpm
for power_method doesn't do anything here either.

I am on a 3.5 debian kernel:
# uname -a
Linux Buzz 3.5-trunk-amd64 #1 SMP Thu Aug 2 17:16:27 UTC 2012 x86_64 GNU/Linux

xorg version is the version from debian 1:7.7+1, so 7.7 and the accompanying
drivers.

Sorry for raising such an old thread but as I said, I cannot imagine that this
is actually impossible to fix.

If I can provide any additional information, I will happily do so.

Regards
  nautsch

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