RE: detection of Isochronous resource manager

[Mark K. <mk...@co...>]

Manfred,
   The OHCI spec (Clause 11 in the 1.06 revision) specifies a 'SelfID Buffer
Pointer Register' and 'SelfID Count Register'. My presumption is that these
register are programmed prior to doing a bus reset, and then the SelfID
packets are stored there by the OHCI controller. The registers are at
offsets h064 & h068 respectively.

   Presumably you could read out the pointer address and go to memory to
find the SelfID packets, and then make your determinations from what is
stored there.

   Alternatively, you might just hunt & peck across the bus looking for
features in a give device. Since you know the root ID, at least you have an
upper bound......

Mark

   

-----Original Message-----
From: Manfred Weihs [mailto:e95...@st...]
Sent: Wednesday, May 17, 2000 3:31 AM
To: Franck Bonin
Cc: Linux1394 devel
Subject: Re: detection of isochronous resource manager


Franck Bonin wrote:
> Just look at self-ID packets :
> 
> If bit 'c' and 'L'(11 & 22) are set to one, the
> corresponding node is condidate to be the isochronous
> resource manager. And the isochronous res manager is
> the candidate node with the largest phy ID (bits
> 24~29)

This sounds reasonable, but there is one problem:
Where do I find the self-ID packets? I have to read the topology map for
that purpose, but not the topology map at the local node, but that one
on the bus manager, because that is the only one which is guaranteed to
have valid data.
So I first have to find out the id of the bus manager. For that purpose,
I think, I can read the bus_manager_id register of the local node. But
the problem is, that it is possible, that we have no bus manager (ie bus
manager id is 0x3f). In that case, I think (but I am not quite sure) I
should read the topology map of the isochronous resource manager (which
does some tasks of the bus manager). So it might be necessary to know
the id of the isochronous resource manager in order to find out the id
of the isochronous resource manager!
So there must be another way to find out the id of the isochronous
resource manager.

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