Re: FireWire/SBP2 Target mode

[Chris Boot]

On 07/02/2012 19:17, Stefan Richter wrote:
> On Feb 07 Chris Boot wrote:
> > On 06/02/2012 23:09, Chris Boot wrote:
> > > On 6 Feb 2012, at 23:00, Julian Calaby wrote:
> > > > 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?
> > >
> > > The fw_address_handler callback is called in interrupt context, and
> > > I can't sleep from within there. As far as I'm aware I must call
> > > fw_send_response() from within the callback and can't defer that until
> > > I've scheduled something on a work queue. Please correct me if I'm
> > > wrong though, as that might be useful anyway.
> >
> > Hmm sorry I've thought about this overnight and clearly I was talking
> > rubbish. Yes, I need to reply in the fw_address_handler but all I tend
> > to do in there is schedule a task to the the main part of the work
> > anyway. As most of the operations require fetching an ORB from the
> > initiator I have to do this from user context.
>
> Technically there are two things to perform:
>
>   1. Finish the inbound IEEE 1394 transaction to the management agent
>      register by means of fw_send_response().  As far as I can tell, you
>      don't have to do that in the address_callback().  But there is little
>      reason not to.
>
>      fw_send_response() ends the lifetime of an fw_request, so read the
>      speed code before you respond.
>
>   2. Finish the inbound SBP-2 transaction; here the login.  This and
>      everything that leads up to it is definitely easiest to implement in
>      a process context, e.g. workqueue item.

Yep I do exactly that - I save the speed then schedule_work() inside the 
address callback, then call fw_send_response() still within the 
callback. The work callback uses fw_run_transaction() to fetch the ORB 
and deal with it.

Cheers,
Chris

--
Chris Boot
bootc@xxxxxxxxx
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