Re: [PATCH] PCI: Blacklist power management of Gigabyte X299 DESIGNARE EX PCIe ports

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

On Tue, Dec 04, 2018 at 09:40:49PM +0100, Lukas Wunner wrote:
> > I wonder if our pci_bridge_d3_possible() heuristics would need to be
> > refined somehow? At least if this blacklist starts growing.
> 
> We do blacklist such non-native hotplug ports, but of course only if
> the Hot-Plug Capable bit is set:
> 
> 	/*
> 	 * Hotplug ports handled by firmware in System Management Mode
> 	 * may not be put into D3 by the OS (Thunderbolt on non-Macs).
> 	 */
> 	if (bridge->is_hotplug_bridge && !pciehp_is_native(bridge))
> 		return false;
> 
> I guess your question boils down to, is there any better way to recognize
> ports which are handled by the platform firmware?

Exactly :) Gigabyte makes lots of motherboards and many of them have
USB-C ports so it may be that they use the same BIOS accross them.

> Does acpiphp bind to this port?

It does, yes but AFAIK it binds to any PCI bus (bridge) if it has an
ACPI companion.