Thanks a lot Jim.
I was away for a couple of days, just saw your mail. I would look into the possible power savings that I can get using your utility. However, I would like to know if there is any impact if I bring down the clock rate for sometime (say 2.5 hrs) and then bring it back to 166 MHz for say 0.5 hr. and then bring it down again for 2.5hrs and so on. Can I cycle the clock rate like this without impact on the CPU or OS? Is it advisable? Because to save power during the 2.5 hrs between my data acquisition, I don't need the full speed of the CPU. Or do I need to reboot?
Thanks and with regards,
- Nagi
Jim Jackson <> wrote:
On Tue, 20 Dec 2005, nagi_kann wrote:
> Has anyone tried 'Advanced Power Management' on the TS7200!
?
APM as per the standard APM or ACPI (http://www.acpi.info/) is not
supported. However there are features you can use to save power.
You can turn off the Ethernet controller, you can reduce the various
internal clock rates. I've written a utility (cctl) to assist with this,
it's in the software section of my TS7200 web page. Also there are some
patches to the kernel to support changing cpu clocking via the cpufreq
interface.
re. ethernet interface, here's what I wrote in a previous thread on the
subject..... "I've found that the ether interface can get into a funny
very slow state if just arbitrarily powered off and on. I would recommend
ifconfig'ing eth0 down, and waiting a few secs, before powering off. And
on power back up, wait a few secs before ifconfig'ing it up again."
and this is a usefull snippet from Bob Lees from another thread ...
"Updat!
e to clk
restriction on enet. Ethernet will work at a 12.5MHz clock
(CPU and BUS) if the connection is at 10MBit (10baseT) which can be forced
by config (haven't done that yet) or by connection to 10MBit hub (have
done that). In the ep93xx_eth driver the auto-negotiation has been
disabled (don't know by whom) because it is set in Redboot. This is fine
until you start changing the clock or disabling/enabling the phy. So if
you intend to change clock and/or disable the phy then you need to
re-enable the auto-negotiate and then do a ifconfig down, ifconfig up
around the clock change/enable phy which causes the phy to re-establish
proper comms. Not yet clear why the clock change causes the problem as
well as the disable/enable, haven't looked at the Micrel data sheet yet.
This is NOT in the patch of 250705."
How much power can you save? Well I have an early TS7200 with an EP9301
(default CPU clock o!
f 166MHz)
and my base line power consumtion is
0.35A at 5v (1.75W). Turning the ethernet controller off and reducing the
CPU and memory clocks to 20MHz and 10MHz resp. I got power consumtion down
to 0.17A at 5V (0.85W).
I'd be interested to see what the savings would be on one of the new
TS7260 boards - I reckon you could really get the power down, because the
residual peripheral board consumption is probably very low.
cheers
Jim
>
> My application of the TS7200 is a data acquisition system wherein data
> acquisition is every 3 hours and the acquisition process takes just 30
> to 35 mins. So for roughly 2 hrs, the TS7200 is consuming power
> without really doing any work. I want to put the unit in an 'low
> power' mode (the ep9302 has support for this but how do I do it from
> Linux?) during the 2.5 hr break between data acquisition cylcles.
>
> Any !
ideas on
how I can acheive it?
>
> I went through the linux literature and found 'apm' (basically for
> laptops), but would it work on the TS7200 (if I compiled it for TS7200)?
>
> Thanks and with regards,
> - Nagi
>
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