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

[Bjorn Helgaas]

[+cc linux-pci]

The original commit was merged via PCI, and I think it's a good idea
to merge fixes to it the same way.  I'll try to merge this in time for
v4.16-rc1.

On Wed, Feb 7, 2018 at 11:33 PM, Alexey Kardashevskiy <aik at ozlabs.ru> wrote:
> Commit 59f47eff03a0 ("powerpc/pci: Use of_irq_parse_and_map_pci() helper")
> correctly states that of_irq_parse_and_map_pci() does the same thing as
> of_irq_parse_pci() does as it simply calls
> of_irq_parse_pci() and irq_create_of_mapping().
>
> However of_irq_parse_and_map_pci() not only returns 0 for success and
> negative value for an error but also a positive virq value from
> irq_create_of_mapping() which the mentioned commit ignores and
> INTx config fails.
>
> This fixes the of_irq_parse_and_map_pci() return value handling.
>
> Fixes: 59f47eff03a0 "powerpc/pci: Use of_irq_parse_and_map_pci() helper"
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>
> ---
>
> Found it on POWER9 + powernv system - almost all devices suddenly lost
> INTx support.
> ---
>  arch/powerpc/kernel/pci-common.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/kernel/pci-common.c b/arch/powerpc/kernel/pci-common.c
> index ae2ede4..acbb44f2 100644
> --- a/arch/powerpc/kernel/pci-common.c
> +++ b/arch/powerpc/kernel/pci-common.c
> @@ -370,7 +370,8 @@ static int pci_read_irq_line(struct pci_dev *pci_dev)
>         memset(&oirq, 0xff, sizeof(oirq));
>  #endif
>         /* Try to get a mapping from the device-tree */
> -       if (!of_irq_parse_and_map_pci(pci_dev, 0, 0)) {
> +       virq = of_irq_parse_and_map_pci(pci_dev, 0, 0);
> +       if (virq <= 0) {
>                 u8 line, pin;
>
>                 /* If that fails, lets fallback to what is in the config
> --
> 2.11.0
>