[PATCH] of/irq: improve error message on irq discovery process failure

[Mark Rutland]

On Wed, Nov 09, 2016 at 12:05:08PM -0200, Guilherme G. Piccoli wrote:
> On PowerPC machines some PCI slots might not have Level-triggered
> interrupts capability (also know as Level Signaled Interrupts - LSI),
> leading of_irq_parse_pci() to complain by presenting error messages
> on the kernel log - in this case, the properties "interrupt-map" and
> "interrupt-map-mask" are not present on the device's node on device
> tree.

If we don't have an interrupt-map on a PCI controller, why don't we
instead log a message regarding that being missing, and give up early?

That sounds like a more generically useful error message; it's also
possible that a DT author simply forgot to add the map, and the platform
has suitable interrupts wired up.

> This patch introduces a different message for this specific case,
> and it also reduces the level of the message from error to warning.
> Before this patch, when an adapter was plugged in a slot without Level
> interrupts capabilities, we saw generic error messages like this:
> 
>     [54.239] pci 002d:70:00.0: of_irq_parse_pci() failed with rc=-22
> 
> Now, with this applied, we see the following specific message:
> 
>     [19.947] pci 0014:60:00.0: of_irq_parse_pci() gave up. The slot of this
>     device has no Level-triggered Interrupts capability.

Following my above example, this has gone from opaque to potentially
misleading.

Thanks,
Mark.