On Mon, 26 Dec 2005, Nagaraj Kanniah wrote:
> 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?
I've not found problems, but I've not done extensive testing.
Caveat experimentor!
I did notice that the system clock went awry at clocks rates less than
10M. I never did figure out why.
> 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?
I'd not thought of doing anything so drastic, but it's a way of ensuring
a known situation.
>
> 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 ...
> "Update 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 of 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
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
>
>
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