Re: [PATCH v2 2/2] Revert "Revert "PCI: Distribute available resources for root buses, too""

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Mon, 14 Nov 2022 13:59:53 +0200
Mika Westerberg <mika.westerberg@linux.intel.com> wrote:

> This reverts commit 5632e2beaf9d5dda694c0572684dea783d8a9492.
> 
> Now that pci_bridge_distribute_available_resources() takes multifunction
> devices int account we can revert this revert to fix the original issue.

into account

Looks fine to me, but I never really figured out the original logic
properly so will leave it to others to give tags on this one.

> 
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
> ---
>  drivers/pci/setup-bus.c | 62 ++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 61 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index f3f39aa82dda..dfa490da728d 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -1768,7 +1768,10 @@ static void adjust_bridge_window(struct pci_dev *bridge, struct resource *res,
>  	}
>  
>  	res->end = res->start + new_size - 1;
> -	remove_from_list(add_list, res);
> +
> +	/* If the resource is part of the add_list remove it now */
> +	if (add_list)
> +		remove_from_list(add_list, res);
>  }
>  
>  static void pci_bus_distribute_available_resources(struct pci_bus *bus,
> @@ -1971,6 +1974,8 @@ static void pci_bridge_distribute_available_resources(struct pci_dev *bridge,
>  	if (!bridge->is_hotplug_bridge)
>  		return;
>  
> +	pci_dbg(bridge, "distributing available resources\n");
> +
>  	/* Take the initial extra resources from the hotplug port */
>  	available_io = bridge->resource[PCI_BRIDGE_IO_WINDOW];
>  	available_mmio = bridge->resource[PCI_BRIDGE_MEM_WINDOW];
> @@ -1982,6 +1987,59 @@ static void pci_bridge_distribute_available_resources(struct pci_dev *bridge,
>  					       available_mmio_pref);
>  }
>  
> +static bool pci_bridge_resources_not_assigned(struct pci_dev *dev)
> +{
> +	const struct resource *r;
> +
> +	/*
> +	 * Check the child device's resources and if they are not yet
> +	 * assigned it means we are configuring them (not the boot
> +	 * firmware) so we should be able to extend the upstream
> +	 * bridge's (that's the hotplug downstream PCIe port) resources
> +	 * in the same way we do with the normal hotplug case.
> +	 */
> +	r = &dev->resource[PCI_BRIDGE_IO_WINDOW];
> +	if (!r->flags || !(r->flags & IORESOURCE_STARTALIGN))
> +		return false;
> +	r = &dev->resource[PCI_BRIDGE_MEM_WINDOW];
> +	if (!r->flags || !(r->flags & IORESOURCE_STARTALIGN))
> +		return false;
> +	r = &dev->resource[PCI_BRIDGE_PREF_MEM_WINDOW];
> +	if (!r->flags || !(r->flags & IORESOURCE_STARTALIGN))
> +		return false;
> +
> +	return true;
> +}
> +
> +static void pci_root_bus_distribute_available_resources(struct pci_bus *bus,
> +							struct list_head *add_list)
> +{
> +	struct pci_dev *dev, *bridge = bus->self;
> +
> +	for_each_pci_bridge(dev, bus) {
> +		struct pci_bus *b;
> +
> +		b = dev->subordinate;
> +		if (!b)
> +			continue;
> +
> +		/*
> +		 * Need to check "bridge" here too because it is NULL
> +		 * in case of root bus.
> +		 */
> +		if (bridge && pci_bridge_resources_not_assigned(dev)) {
> +			pci_bridge_distribute_available_resources(bridge, add_list);
> +			/*
> +			 * There is only PCIe upstream port on the bus
> +			 * so we don't need to go futher.
> +			 */
> +			return;
> +		}
> +
> +		pci_root_bus_distribute_available_resources(b, add_list);
> +	}
> +}
> +
>  /*
>   * First try will not touch PCI bridge res.
>   * Second and later try will clear small leaf bridge res.
> @@ -2021,6 +2079,8 @@ void pci_assign_unassigned_root_bus_resources(struct pci_bus *bus)
>  	 */
>  	__pci_bus_size_bridges(bus, add_list);
>  
> +	pci_root_bus_distribute_available_resources(bus, add_list);
> +
>  	/* Depth last, allocate resources and update the hardware. */
>  	__pci_bus_assign_resources(bus, add_list, &fail_head);
>  	if (add_list)