RE: Bus Reset

[Jeff M. <Jef...@ef...>]

Sebastien,

Thanks for prompt response.  Yes, the bus reset signal would generate
whenever the target node is in "sleep" mode.

Jeff

-----Original Message-----
From: Sebastien Rougeaux [mailto:Seb...@sy...]
Sent: Sunday, April 16, 2000 9:52 PM
To: Jef...@ef...
Cc: lin...@li...
Subject: Re: Bus Reset


>>>>> "Jeff" == Jeff Mak <Jef...@ef...> writes:

Jeff> I am making use of raw1394 (dev_open) to connect to the other node
Jeff> through OHCI kernel driver, when there is a change in power status at
Jeff> PHY of the other node, a bus reset would be generated from the
hardware.
Jeff> Is it true that the connection in between would be lost?  In other
Jeff> words, can I send any other command to the target node using the same
Jeff> handle?  I know that this is not OHCI specific question but since I am
Jeff> using OHCI kernel driver written by you, I believe you may have some
Jeff> experience on that.

I don't think bus reset are handled properly yet in the current version
of the linux ieee1394 driver. If a bus reset occurs, the node numbers on 
the bus are re-assigned, and I don't think that libraw is designed to deal 
with that situation (I might be wrong though). Especially, the ohci driver
receives a specific phy packet that indicates precisely when the bus 
configuration has been modified, but this packet is currently being 
discarded since the subsystem doesn't accept it... I have to talk to 
Andreas about that.

Jeff> The reason why I ask this question is: I am currently trying to talk
to
Jeff> a target node which has a "wake up" feature.  In other words, if the
Jeff> target node is idle for period of time, it will try to shutdown itself
Jeff> until it receives a "wake up" command from my linux box.  However,
when
Jeff> the target node is idle and auto shutoff.  Bus reset would be
generated
Jeff> causing I cannot get the respond from the target node anymore using
the
Jeff> same raw1394_handle.  I have tried to deactivate the bus reset event
on
Jeff> interrupt of OHCI driver but it is not working.  I believe
deactivating
Jeff> the interrupt event mask on bus reset is just ignore the bus reset on
Jeff> kernel driver side.

Do you mean that everytime the node goes in 'sleep' mode, a bus reset is
generated ???

Jeff> I suppose if the target node get the power from the firewire bus and
my
Jeff> firewire card is a power supplier, there shouldn't be any bus reset
even
Jeff> if the target node is in power off mode.  Is my understanding correct?
Jeff> I know that this is IEEE1394 specific and if you have any suggestion,
Jeff> please let me know.

Sorry I don't know about that particular point of the ieee1394 standard.

-- 
Sebastien Rougeaux
RSISE, The Australian National University