Re: [PATCH 1/4] arm64: pci: acpi: Use pci_assign_unassigned_root_bus_resources()

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Sat, Jun 15, 2019 at 10:23:56AM +1000, Benjamin Herrenschmidt wrote:
> Instead of the simpler
> 
> 	pci_bus_size_bridges(bus);
> 	pci_bus_assign_resources(bus);
> 
> Use pci_assign_unassigned_root_bus_resources(). This should have no effect
> as long as we are reassigning everything. Once we start honoring FW
> resource allocations, this will bring up the "reallocation" feature
> which can help making room for SR-IOV when necessary.

I would like to add more details on why we want to make this change,
I will update the log when we merge it, it is a bit too late for v5.3,
even if in theory no functional change is intended.

> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> ---
>  arch/arm64/kernel/pci.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/kernel/pci.c b/arch/arm64/kernel/pci.c
> index bb85e2f4603f..1419b1b4e9b9 100644
> --- a/arch/arm64/kernel/pci.c
> +++ b/arch/arm64/kernel/pci.c
> @@ -193,8 +193,7 @@ struct pci_bus *pci_acpi_scan_root(struct acpi_pci_root *root)
>  	if (!bus)
>  		return NULL;
>  
> -	pci_bus_size_bridges(bus);
> -	pci_bus_assign_resources(bus);
> +	pci_assign_unassigned_root_bus_resources(bus);

These hunks should be identical, minus the additional resource size
handling and realloc policy (which are *missing* features in current
code). We must document this change in the log.

Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

>  	list_for_each_entry(child, &bus->children, node)
>  		pcie_bus_configure_settings(child);
> -- 
> 2.17.1
>