Re: [PATCH v7 02/17] ACPI: scan: Add a weak function to reorder the IRQCHIP probe

[Bjorn Helgaas]

On Mon, Jul 29, 2024 at 07:52:24PM +0530, Sunil V L wrote:
> Unlike OF framework, the irqchip probe using IRQCHIP_ACPI_DECLARE has no
> order defined. Depending on the Makefile is not a good idea. So,
> usually it is worked around by mandating only root interrupt controller
> probed using IRQCHIP_ACPI_DECLARE and other interrupt controllers are
> probed via cascade mechanism.
> 
> However, this is also not a clean solution because if there are multiple
> root controllers (ex: RINTC in RISC-V which is per CPU) which need to be
> probed first, then the cascade will happen for every root controller.
> So, introduce a architecture specific weak function to order the probing
> of the interrupt controllers which can be implemented by different
> architectures as per their interrupt controller hierarchy.

Nit: I think it's nice if the commit log and even the subject line
includes the actual *name* of the function being added.

s/a architecture/an architecture/

No need to repost for these.

> Signed-off-by: Sunil V L <sunilvl@xxxxxxxxxxxxxxxx>
> ---
>  drivers/acpi/scan.c  | 3 +++
>  include/linux/acpi.h | 2 ++
>  2 files changed, 5 insertions(+)
> 
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 59771412686b..52a9dfc8e18c 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -2755,6 +2755,8 @@ static int __init acpi_match_madt(union acpi_subtable_headers *header,
>  	return 0;
>  }
>  
> +void __weak arch_sort_irqchip_probe(struct acpi_probe_entry *ap_head, int nr) { }
> +
>  int __init __acpi_probe_device_table(struct acpi_probe_entry *ap_head, int nr)
>  {
>  	int count = 0;
> @@ -2763,6 +2765,7 @@ int __init __acpi_probe_device_table(struct acpi_probe_entry *ap_head, int nr)
>  		return 0;
>  
>  	mutex_lock(&acpi_probe_mutex);
> +	arch_sort_irqchip_probe(ap_head, nr);
>  	for (ape = ap_head; nr; ape++, nr--) {
>  		if (ACPI_COMPARE_NAMESEG(ACPI_SIG_MADT, ape->id)) {
>  			acpi_probe_count = 0;
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 0687a442fec7..3fff86f95c2f 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -1343,6 +1343,8 @@ struct acpi_probe_entry {
>  	kernel_ulong_t driver_data;
>  };
>  
> +void arch_sort_irqchip_probe(struct acpi_probe_entry *ap_head, int nr);
> +
>  #define ACPI_DECLARE_PROBE_ENTRY(table, name, table_id, subtable,	\
>  				 valid, data, fn)			\
>  	static const struct acpi_probe_entry __acpi_probe_##name	\
> -- 
> 2.43.0
>