[ltp] Power drain workaround with radeonfb module?

[Marius Gedminas]

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On Sun, Oct 28, 2007 at 03:42:17PM +0100, Felix E. Klee wrote:
> On Thinkwiki it's stated [1] that doing "modprobe radeonfb" before
> starting X can solve the high power drain issue on certain Thinkpads.
>=20
> Can that work? I previously thought that radeonfb has to be built into
> the kernel,

It used to work for me, with radeon as a module.

> and that's what a recent test confirms with Ubuntu 7.10
> (Gutsy Gibbon) on a T41 (2373-3kg):
>=20
> 1. The system started up in text mode (no X).
>=20
> 2. I loaded the module:
>=20
>   # modprobe radeonfb
>   # dmesg
>     [...]
>     [  932.232000] radeonfb: Monitor 1 type LCD found
>     [  932.232000] radeonfb: Monitor 2 type CRT found
>     [  932.232000] radeonfb: panel ID string: 1024x768               =20
>     [  932.232000] radeonfb: detected LVDS panel size from BIOS:
>     1024x768
>     [  932.232000] radeondb: BIOS provided dividers will be used
>     [  932.352000] radeonfb: Dynamic Clock Power Management enabled
>     [  932.352000] radeonfb: IBM Thinkpad R50/R51/T40/T41 detected,
>     enabling workaround
>     [  932.352000] radeonfb (0000:01:00.0): ATI Radeon Lf=20
>=20
> 3. I executed sleep.sh, from Thinkwiki [2]:
>=20
>   # ./sleep.sh; reboot
>   [...]
>   # tail /var/log/battery.log
>     [...]
>     Sun Oct 28 14:27:16 CET 2007
>     before: 12150 mWh
>     after: 11200 mWh
>     diff: -950 mWh
>     seconds: 3023 sec
>     result: -1131 mW
>     Your model seems to be affected.

At this point, if you check dmesg, do you see the following two
messages:

  radeonfb (0000:01:00.0): suspending to state: 2...
  radeonfb (0000:01:00.0): switching to D2 state...

before the machine went to sleep?

> On the same hardware, with Slackware 10.2 and a 2.16.14.4 kernel with
> radeonfb built in, the power drain issue is solved.
>=20
> [1]
> http://www.thinkwiki.org/wiki/Problem_with_high_power_drain_in_ACPI_sleep
>=20
> [2] http://www.thinkwiki.org/wiki/ACPI_sleep_power_drain_test_script

Marius Gedminas
--=20
BYTE editors are people who separate the wheat from the chaff, and then
carefully print the chaff.

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