discrete radeon HD 6400M/7400M intense heating even though it's "off"

Submitted by Tomas Pospisek

Assigned to Default DRI bug account

Link to original bug (#67178)

Description

kernel 3.11-rc1 (also tested with 3.10 from Debian, 3.7, 3,2)

lspci -vnnn | grep VGA

00:02.0 VGA compatible controller [0300]: Intel Corporation 2nd
Generation Core Processor Family Integrated Graphics Controller
[8086:0116] (rev 09) (prog-if 00 [VGA controller])
01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc.
[AMD/ATI] Seymour [Radeon HD 6400M/7400M Series] [1002:6760] (rev ff)
(prog-if ff)

This is a HP Pavillon dv7 6130ez

Sometimes, at random, the radeon card goes into full heat production mode. This seems to occur a while (a few minutes?) after wakeup from resume, however I'm not sure about that. Suspending and resuming the laptop a few times (1 <= x <= ~4) seems to calm the card down again.

Power consumption according to powertop goes from ~14W up to ~50W. This happens even though the card should be in theory switched off. Aka:

cat /sys/kernel/debug/vgaswitcheroo/switch

0:IGD:+:Pwr:0000:00:02.0
1:DIS: :Off:0000:01:00.0

echo IGD > /sys/kernel/debug/vgaswitcheroo/switch

echo OFF > /sys/kernel/debug/vgaswitcheroo/switch

doesn't seem to have no effect whatsoever.

It *seems* that setting "radeon.dpm=1" kernel boot options and then:

# echo "battery" > /sys/class/drm/card$no/device/power_dpm_state

puts the card in an "active" but "relatively low" power consumption mode. It is then using about 20W (instead of the "normal" ~14W) so it's continuously faning out slightly warm air. And it "seems that when the card is running in this mode, then it won't get so often, or ever (I'm not very sure) into the berserk heating mode.

The lowest observed power consumption of the laptop is ~7W. It'd be very nice if it'd be possible to shut the card down electrically via software and stay in this 7W mode.