Re: [PATCH] perf/arm-smmuv3: Propagate errors from optional IRQ lookup

[Bui Duc Phuc]

Hi Will,

> > > Sorry, but how is failing the probe possibly better than continuing without
> > > the optional interrupt? Add a diagnostic if you like, but aborting the probe
> > > feels completely unnecessary to me.
> > >
> >
> > My understanding is that the driver is designed to be generic and
> > support various hardware configurations, some with this resource (IRQ,
> > GPIO, clock, ...) and some without.
> >
> > If a configuration describes the resource, it means the board is
> > designed to use it. For that hardware the "optional" nature of the
> > driver no longer applies, so if we fail to get the resource the error
> > should be returned.
> >
> > A log alone is easy to miss, and the root cause still has to be found
> > and fixed later anyway. Failing the probe makes the problem visible
> > right away, when the board is being brought up.
>
> If you're doing bring-up, you should probably pay attention to the logs.

OK. Then we should probably write it as:
-------------------------------------------------------------------------
irq = platform_get_irq_optional(pdev, 0);
if (irq < 0 && irq != -ENXIO)
        return dev_err_probe(pdev, irq, "failed to get irq\n");
-------------------------------------------------------------------------

> If you're trying to use the device, you probably don't care about the
> interrupt.

If we're worried about returning an error here because it might cause
the device probe to fail, then shouldn't we hide errors from all
the other functions in probe() as well? :-)

Best regards,
Phuc