Power management and linux1394?

Stefan Richter wrote on 2004-06-06:

>On the other hand, the 1394 spec also describes software related
>features for power management on 1394 buses. Two different topics
>are covered by these power management features:
>
>1. A bus manager software may activate the higher functions of
> power draining devices. The bus manager checks how much power
> is provided and how much is consumed overall by all nodes. It
> may then send "link on" packets to devices that did not power
> up themselves.
> You can check with gscanbus if the zip drive has an inactive link.
> In that case, a link-on packet may help.
>
>2. A bus manager software may suspend and resume devices, similar
> to a PC OS that suspends and resumes internal PC hardware.
>
>The Linux ieee1394 driver does not implement bus management
>(except for isochronous resource management which is unrelated to
>power management).
>
>
>
At this time I did not worry about this. Things have changed now that I
got an external
disk enclosure which (I think) uses those features. It works well on
Windows2000
and is supposed to work well on MacOS X (have not tested). It does not work
well at all on Linux: The unit does not spin reliably up, and even
worse, when it
does, it spins the disks down again after some minutes, only to spin them up
seconds later. No need to say this is not good at all.

Using gscanbus I can sometimes not see the device at all (link
inactive), sometimes
it is visible (when the disks are on) and it vanished and comes again
when the
disks are going up and down and up and down.

I assume that the problem is related to those power managent functions, as
this enclosure only poweres on the disks when the computer it's connected to
is on. If it's off (e.g. going to standby or turning off), they spin
down nicely.
All other enclosures power up the disks whenever they see electrivity from
the main power supply of the enclosure.

Now my question: what is needed to check whether that enclosure uses
IEEE1394 power
management functions? I already contacted the manufacturer, but so far
no reply. As it's not
a question a sales rep can answer, I don't expect an answer quickly.

I thought it might be a simple hardware trick (sensing voltage on the
firewire sockets),
but using a notebook with a 4 pin firewire plug worked reliably, so it
must be something
else like a software command.

If it uses power management functions and Linux1394 does not support
them, what
are the options? 1394commander? Implementing those functions in the
linux1394 driver?
I am not good enough to implement those, but I'll do whatever I can do
to make this work.

Harald

-------------------------------------------------------
SF email is sponsored by - The IT Product Guide
Read honest & candid reviews on hundreds of IT Products from real users.
Discover which products truly live up to the hype. Start reading now.
http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click
_______________________________________________
mailing list Linux1394-user@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux1394-user
Received on Mon Apr 4 15:59:09 2005