Re: [PATCH] cxl: Add generic MSI/MSI-X interrupt support

[Davidlohr Bueso]

Thanks for having a look.

On Thu, 13 Oct 2022, Jonathan Cameron wrote:

> > +struct cxl_irq_cap {
> > +	const char *name;
> > +	int (*get_max_msgnum)(struct cxl_dev_state *cxlds);
>
> For the CPMU case I need to walk the register locator dvsec block so need
> the callback to take the pci_dev not the cxl_dev_state.

Hmm ok, however maybe I'm missing something, but given a pdev, do we have a
way to get back to the cxlds?

...

> >  static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> >  {
> >  	struct cxl_register_map map;
> > @@ -498,6 +558,9 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> >  	if (IS_ERR(cxlmd))
> >  		return PTR_ERR(cxlmd);
> >
> > +	/* TODO: When there are users, this return value must be checked */
> > +	cxl_pci_alloc_irq_vectors(cxlds);
> > +
>
> Gut feeling is this will end up moving ahead of any of the sub device creation
> because many of them end up needing interrupts.
>
> Also check response from the start - can't see a reason to not do so as we
> won't be registering any at all if no callbacks provided.
>
> So I'd move it above the devm_cxl_add_memdev() call.

Will do. In addition, are you ok with grouping the irq setup for each cxl
feature/component, ie:

if (cxl_pci_alloc_irq_vectors(cxlds) > 0) {
   cxl_setup_mbox_irq();
   cxl_setup_events_irq();
   cxl_setup_pmu_irq();
}

I ask mostly from the mailbox perspective, in that we already have
a mbox setup call and can certainly understand if people would prefer
it there, but I tend to prefer the above (logically wrt irqs).

Thanks,
Davidlohr