Open firmware and Pismo

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Joined: Jun 1 2004
Posts: 67

Hi All,

I've been delving around in open firmware on my Pismo to see if I can control the internal fan, or at least set a better temp. for it to come on at.

In the device tree I've found the via-pmu, and under this is a node called 'power-mgt'. A property of this is called 'thermal-info'. As far as I know this must be related to the temp sensor in the Pismo because the G4 chip I have in it doesn't have the thermal assist temp diode on the chip enabled.

To check that this was specific to the Pismo I found the same 'power-mgt' property on a Digital Audio G4, which had everything listed the same, apart from the 'thermal-info', which was missing.

I've now hit a problem. There are 4 values of data encoded in open firmware for the 'thermal-info'. I believe they are the limits for the fan, as they do not change from boot up o when the computer is definitely toasty.

I can write one value by using the following command:

12345678 encode-int " thermal-info" property

However, I need to be able to write all 4 values - and I don't know the open firmware commands to do this... could anyone help?

Thanks (and sorry for the rambling post),


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Joined: Jun 1 2004
Posts: 67
Using OF commands, after amen

Using OF commands, after amending the settings for thermal-info I got the fan to turn on straight after booting, by setting them to 01010200 00000000 01010200 00000000.

With the open firmware dump below of the values for via-pmu / power-mgt could anyone explain what the values present could likely be. i.e. are the set of 4 hex values likely to be 2 sets of values, or 4 separate ones?

I decoded each of the hex values and got 16843264 for hex 01010200 and 1213468963 for hex 48434843. I think these refer to temperature values (perhaps F?).

ff918050: /pci@f2000000/mac-io@17/via-pmu@16000/power-mgt

compatible 7669612d 706d752d 393900.. ........ "via-pmu-99"
device_type 706f7765 722d6d67 7400.... ........ "power-mgt"
max-aux-power 00000000 ........ ........ ........ ....
name 706f7765 722d6d67 7400.... ........ "power-mgt"
prim-info 000000ff 00000060 00003e80 00017fb5 .......`..>.....
0010: 0000d607 00000000 00021300 46000220 ............F..
0020: 101400.. ........ ........ ........ ...
registry-name 65787469 6e742d67 70696f31 00...... extint-gpio1.
thermal-info 01010200 00000000 48434843 00000000 ........HCHC....

Any knowledge people may have on this and Open Firmware properties would be much appreciated.