Re: [PATCH kernel v2] powerpc/pci: Fix broken INTx configuration via OF

On Thu, Feb 8, 2018 at 11:54 PM, Michael Ellerman [off-list ref] wrote:

Alexey Kardashevskiy [off-list ref] writes:

quoted

Commit 59f47eff03a0 ("powerpc/pci: Use of_irq_parse_and_map_pci() helper")
replaced of_irq_parse_pci() + irq_create_of_mapping() with
of_irq_parse_and_map_pci() but this change lost virq returned by
irq_create_of_mapping() so virq remained zero causing INTx
misconfiguration.

This fixes pci_read_irq_line() not to loose a virq returned by
of_irq_parse_and_map_pci().

Fixes: 59f47eff03a0 "powerpc/pci: Use of_irq_parse_and_map_pci() helper"
Signed-off-by: Alexey Kardashevskiy <redacted>
---
Changes:
v2:
* changed the condition from <=0 to !=0 as by design
of_irq_parse_and_map_pci() can only return 0 for an error and virq>0.

It returns int, so you should store the result in an int, and check the
result for <= 0.

Otherwise if it starts returning a negative error value this code will
break.

That won't happen until we're confident all callers expect NO_IRQ is
only 0 and don't treat negative as NO_IRQ. I expect that to be never,
but maybe of_irq_parse_and_map_pci calls can be audited more easily
than of_irq_parse_and_map. We ended up with of_irq_get() because we
need to return error codes.

Rob