Hi, On Tue, Feb 7, 2012 at 09:28, Chris Boot <bootc@xxxxxxxxx> wrote: > On 6 Feb 2012, at 20:26, Stefan Richter wrote: > >> On Feb 06 Chris Boot wrote: >>> On 06/02/2012 14:43, Clemens Ladisch wrote: >>>> Chris Boot wrote: >>>>> You can pull the code from: >>>>> git://github.com/bootc/Linux-SBP-2-Target.git >>>> >>>> The TODO file says: >>>>> * Update Juju so we can get the speed in the fw_address_handler callback >>>> >>>> What is the speed needed for? >>> >>> "The speed at which the block write request to the MANAGEMENT_AGENT >>> register is received shall determine the speed used by the target for >>> all subsequent requests to read the initiator’s configuration ROM, fetch >>> ORB’s from initiator memory or store status at the initiator’s >>> status_FIFO. Command block ORB’s separately specify the speed for >>> requests addressed to the data buffer or page table." >>> >>> (T10/1155D Revision 4 page 53/54) >> >> I guess it is not too hard to add this to the AR-req handler. On the >> other hand, I see little reason to follow the SBP-2 spec to the letter >> here. The target driver could just use the maximum speed that the core >> figured out. On the other hand, this requires of course >> - the target to wait for core to finish scanning an initiator, >> - the core to offer an API to look up an fw_device by a >> card--generation--nodeID tuple. >> >> The intention of the spec is IMO clearly to enable target implementations >> that do not need to implement topology scanning. I have a hard time to >> think of a valid scenario where an initiator needs to be able to steer a >> target towards a lower wire speed than what the participating links and >> PHYs actually support. > > The only thing stopping me from getting the speed is the fact that struct fw_request is opaque. The value is easily available from request->response.speed and I kind of do that already in a very hackish way. I've sent a separate patch which adds a function that can be used to access that one value. > > Waiting until the bus scan is complete isn't actually that great as I see the first LOGIN requests often before the fw_node is seen at all. I'd have to turn away the requester and hope they try again. I'm fairly sure my little tweak in my patch is a simple enough solution. Stupid question: Could you use a completion queue or something equivalent to wait until you have seen the fw_node, *then* process the LOGIN request? Thanks, -- Julian Calaby Email: julian.calaby@xxxxxxxxx Profile: http://www.google.com/profiles/julian.calaby/ .Plan: http://sites.google.com/site/juliancalaby/ -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
