Re: [PATCH 2/2] PCI: Skip resource distribution when no hotplug bridges

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Sat, Jun 22, 2019 at 04:03:11PM -0500, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@google.com>
> 
> If "hotplug_bridges == 0", "!dev->is_hotplug_bridge" is always true, so the
> loop that divides the remaining resources among hotplug-capable bridges
> does nothing.
> 
> Check for "hotplug_bridges == 0" earlier, so we don't even have to compute
> the amount of remaining resources.  No functional change intended.
> 
> ---
> 
> I'm pretty sure this patch preserves the previous behavior of
> pci_bus_distribute_available_resources(), but I'm not sure that
> behavior is what we want.
> 
> For example, in the following topology, when we process bus 10, we
> find two non-hotplug bridges and no hotplug bridges, so IIUC we return
> without distributing any resources to them.  But I would think we
> should try to give 10:1c.0 more space if possible because it has a
> hotplug bridge below it.
> 
>   00:1c.0: hotplug bridge to [bus 10-2f]
>     10:1c.0: non-hotplug bridge to [bus 11-2e]
>       11:00.0: hotplug bridge to [bus 12-2e]
>     10:1c.1: non-hotplug bridge to [bus 2f]

Yes, I agree in this case we want to preserve more space for 10:1c.0.

For this patch,

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>