Re: [PATCH 02/25] ACPI: irq: Add IRQ affinity reporting interface

Rafael J. Wysocki
2025-09-08T17:20:27Z

On Mon, Sep 8, 2025 at 6:31 PM Marc Zyngier <maz@kernel.org> wrote:
>
> Plug the irq_populate_fwspec_info() helper into the ACPI layer
> to offer an IRQ affinity reporting function. This is currently
> only supported for the CONFIG_ACPI_GENERIC_GSI configurations,
> but could later be extended to legacy architectures if necessary.
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
> drivers/acpi/irq.c | 15 +++++++++++++++
> include/linux/acpi.h | 7 +++++++
> 2 files changed, 22 insertions(+)
>
> diff --git a/drivers/acpi/irq.c b/drivers/acpi/irq.c
> index 76a856c32c4d0..22f93fe23ddce 100644
> --- a/drivers/acpi/irq.c
> +++ b/drivers/acpi/irq.c
> @@ -300,6 +300,21 @@ int acpi_irq_get(acpi_handle handle, unsigned int index, struct resource *res)
> }
> EXPORT_SYMBOL_GPL(acpi_irq_get);
>
> +const struct cpumask *acpi_irq_get_affinity(acpi_handle handle,
> + unsigned int index)
> +{
> + struct irq_fwspec_info info;
> + unsigned long flags;
> +
> + if (!acpi_irq_parse_one(handle, index, &info.fwspec, &flags)) {
> + if (!irq_populate_fwspec_info(&info) &&
> + info.flags & IRQ_FWSPEC_INFO_AFFINITY_VALID)
> + return info.affinity;
> + }

I would prefer fewer logical negations to be used in this, for instance:

if (acpi_irq_parse_one(handle, index, &info.fwspec, &flags))
return NULL;

if (irq_populate_fwspec_info(&info))
return NULL;

if (info.flags & IRQ_FWSPEC_INFO_AFFINITY_VALID)
return info.affinity;

return NULL;

> +
> + return NULL;
> +}
> +
> /**
> * acpi_set_irq_model - Setup the GSI irqdomain information
> * @model: the value assigned to acpi_irq_model
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 1c5bb1e887cd1..c506ae4bacc86 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -1509,12 +1509,19 @@ static inline int acpi_parse_spcr(bool enable_earlycon, bool enable_console)
>
> #if IS_ENABLED(CONFIG_ACPI_GENERIC_GSI)
> int acpi_irq_get(acpi_handle handle, unsigned int index, struct resource *res);
> +const struct cpumask *acpi_irq_get_affinity(acpi_handle handle,
> + unsigned int index);
> #else
> static inline
> int acpi_irq_get(acpi_handle handle, unsigned int index, struct resource *res)
> {
> return -EINVAL;
> }
> +static inline const struct cpumask *acpi_irq_get_affinity(acpi_handle handle,
> + unsigned int index)
> +{
> + return NULL;
> +}
> #endif
>
> #ifdef CONFIG_ACPI_LPIT
> --