Messages in this thread | | | Subject | RE: [PATCH 7/9] RapidIO: Add handling for PW message from a lost device | Date | Mon, 16 Aug 2010 11:02:21 -0700 | From | "Bounine, Alexandre" <> |
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Micha Nelissen wrote: > > Alexandre Bounine wrote: > > Add check if PW message source device is accessible and change PW message > > handler to recover if PW message source device is not available anymore (power > > down or link disconnect). > > I am not quite sure what the point is of this patch. What do you need to > recover from?
From failed maintenance read. In the previous version PW handler had troubles if maintenance read request fails. Now I am trying to detect lost or remover devices as soon as I see broken link.
> > > To avoid possible loss of notification, the PW message handler scans the route > > back from the source device to identify end of the broken link. > > Do you mean if port-writes are dropped? Then they did not reach you in > the first place. If a link in between is broken, the associated switch > will 'complain' and send port-writes, no?
Situation that I am trying to resolve is mostly applicable to larger systems that have multiple complex boards (or chassis/domains) connected together. Power down sequence on the board (chassis) combined with switch hierarchy may allow switch to send PW message to the host before its power is off. This will create an orphaned PW message. At the same time there is no guarantee that PW message from the associated switch will reach the host. That "real" PW message may be dropped by the controller (85xx is good example). Everything depends on number of PW messages directed to the host/controller. I am trying to use the first available notification to service device removal. If the "real" PW message is received it should be processed without any further action.
Alex.
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