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SubjectRe: [PATCH] m68k/mac: Allocate IOP message pool and queues dynamically

On Sun, 30 Jun 2013, Brad Boyer wrote:

> On Sun, Jun 30, 2013 at 12:02:22PM +0200, Geert Uytterhoeven wrote:
> >
> > if (iop_scc_present) {
> > printk("IOP: detected SCC IOP at %p\n", iop_base[IOP_NUM_SCC]);
> > + alloc_msg_queue(IOP_NUM_SCC);
>
> Technically, this isn't actually useful. As long as we never start this
> IOP, it can't ever send or be sent any messages.

That assumes that the SCC IOP is in a stopped state after iop_preinit().
But I don't think that's the case. If it is technically possible to
exchange messages with a device in bypass mode (?) then I think the code
above is correct.

> > @@ -315,6 +307,9 @@ void __init iop_register_interrupts(void)
> > } else {
> > printk("IOP: the ISM IOP seems to be alive.\n");
> > }
>
> The if/else above isn't useful if it is run before the call to
> iop_start. However, it's also useless if it is called immediately after
> the call to iop_alive which is now below. It was supposed to eventually
> be called in the background on a regular schedule, but that never
> happened.
>

I agree. That if/else statement and the conditional printk's should be
omitted.

I had thought that in the existing code the interrupt service routine was
registered before the call to iop_start() but in fact iop_start() happens
first. Looks like a bug to me. The interrupt handler needs to be able to
acknowledge unsolicited messages...

Finn


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