On Mon, Sep 5, 2022 at 3:50 PM Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> wrote: > > On Mon, Sep 05, 2022 at 03:26:28PM +0800, Kai-Heng Feng wrote: > > Hi Mika, > > > > On Mon, Sep 5, 2022 at 3:06 PM Mika Westerberg > > <mika.westerberg@xxxxxxxxxxxxxxx> wrote: > > > > > > Hi, > > > > > > On Mon, Sep 05, 2022 at 02:56:22PM +0800, Kai-Heng Feng wrote: > > > > AMD USB4 can not detect external PCIe devices like external NVMe when > > > > it's hotplugged, because card/link are not up: > > > > > > > > pcieport 0000:00:04.1: pciehp: pciehp_check_link_active: lnk_status = 1101 > > > > > > I think the correct solution is then to block them from runtime > > > suspending entirely. > > > > Do you mean disable runtime suspend completely? Or just block runtime > > suspend for a period? > > Completely. The port should enter D3 if it cannot wake up and Linux does > not even enable runtime PM for such ports unless they declare > "HotPlugSupportInD3" in their ACPI description: > > https://docs.microsoft.com/en-us/windows-hardware/drivers/pci/dsd-for-pcie-root-ports#identifying-pcie-root-ports-supporting-hot-plug-in-d3 > > So that property should not be there if they cannot wake up. The port can wake up but card/link isn't up yet. > > > > > Use `lspci` to resume pciehp bridges can find external devices. > > > > > > > > A long delay before checking card/link presence doesn't help, either. > > > > The only way to make the hotplug work is to enable pciehp interrupt and > > > > check card presence after the TB switch is added. > > > > > > > > Since the topology of USB4 and its PCIe bridges are siblings, hardcode > > > > the bridge ID so TBT driver can wake them up to check presence. > > > > > > Let's not add PCI things into TBT driver unless absolutely necessary. > > > > OK. It's getting harder as different components are intertwined > > together on new hardwares... > > > > > > > > At least on Intel hardware the PCIe hotplug is signaled by SCI when the > > > root port is in D3, I wonder if AMD has something similar. > > > > Yes those root ports are resumed to D0 when something is plugged. They > > however fail to detect any externel PCIe devices. > > Hmm, so you see the actual hotplug but the tunneled PCIe link may not be > detected? Does the PCIe "Card Present" (or Data Link Layer Active) > status change at all or is it always 0? It changes only after tb_switch_add() is called. Kai-Heng
