On Sat, Mar 24, 2018 at 02:48:07PM +0100, Lukas Wunner wrote: > On Thu, Mar 22, 2018 at 02:36:30PM -0500, Bjorn Helgaas wrote: > > I hope we can avoid adding suspend_late/resume_early callbacks in > > struct pcie_port_service_driver, > > I'm fairly certain that we cannot avoid adding at least a ->resume_noirq > callback to struct pcie_port_service_driver to fix a pciehp use case: > > On ->resume_noirq the PCI core walks down the hierarchy to put every > device in D0 and restore its state (with a few exceptions such as direct > complete). However with hotplug ports, it's possible that the user has > unplugged devices while the system was asleep, or replaced them with > other devices. That's a very real use case with Thunderbolt and we're > handling it poorly or not at all currently. We need to check if the > devices below a hotplug port are still there or have been replaced > (can probably be recognized by looking at vendor/device IDs across the > entire sub-hierarchy) during the ->resume_noirq phase. We could mark > them with pci_dev_set_disconnected(), then skip putting them into D0 > if that flag has been set. This is definitely a real issue, and I think it affects more than just Thunderbolt. We've never handled undocks very well either. I certainly agree we need a way to handle this; I would just rather do it by integrating pciehp and the other services more directly into the PCI core instead of using the port driver. Maybe we'll need a short-term ->resume_noirq, but I don't think the port driver is a good long-term solution. Bjorn
