On Sun, Jan 15, 2017 at 09:03:45PM +0100, Lukas Wunner wrote: > Hotplug ports generally block their parents from suspending to D3hot as > otherwise their interrupts couldn't be delivered. > > An exception are Thunderbolt host controllers: They have a separate > GPIO pin to side-band signal plug events even if the controller is > powered down or its parent ports are suspended to D3. They can be told > apart from Thunderbolt controllers in attached devices by checking if > they're situated below a non-Thunderbolt device (typically a root port, > or the downstream port of a PCIe switch in the case of the MacPro6,1). > > To enable runtime PM for Thunderbolt on the Mac, the downstream bridges > of a host controller must not block runtime PM on the upstream bridge as > power to the chip is only cut once the upstream bridge has suspended. > Amend the condition in pci_dev_check_d3cold() accordingly. > > This change does not impact non-Macs as their Thunderbolt hotplug ports > are handled by the firmware rather than natively by the OS: The hotplug > ports are not allowed to suspend in pci_bridge_d3_possible() and keep > their parent ports awake all the time. Consequently it is meaningless > whether they block runtime PM on their parent ports or not. > > Cc: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> Reviewed-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
