On Tue, Aug 27, 2019 at 3:48 PM Rafael J. Wysocki <raf...@kernel.org> wrote: > That depends on what exactly happens when you try to do the D0-D3-D0 > with setpci. If the device becomes unreachable (or worse) after that, > it indicates a platform issue. It should not do any harm at the > least. > > However, in principle D0-D3-D0 at the PCI level alone may not be > sufficient, because ACPI may need to be involved.
After using setpci to do D0-D3-D0 transitions, the xhci module fails to probe. xhci_hcd 0000:03:00.3: WARN: xHC restore state timeout xhci_hcd 0000:03:00.3: PCI post-resume error -110! But maybe it's not a great test; as you say I'm not involving ACPI, and also if Linux has a reason for not runtime suspending PCI devices without drivers present then maybe I should also not be doing this. > I think that PM-runtime should suspend XHCI controllers without > anything on the bus under them, so I wonder what happens if > ".../power/control" is set to "on" and then to "auto" for that device, > with the driver loaded. Good hint. # echo on > /sys/bus/pci/devices/0000\:03\:00.3/power/control # echo auto > /sys/bus/pci/devices/0000\:03\:00.3/power/control # echo 1 > /sys/bus/usb/devices/1-4/remove # cat /sys/bus/pci/devices/0000\:03\:00.3/power/runtime_status suspended # echo on > /sys/bus/pci/devices/0000\:03\:00.3/power/control The final command there triggers these messages (including a printk I added in pci_raw_set_power_state): xhci_hcd 0000:03:00.3: pci_raw_set_power_state from 3 to 0 xhci_hcd 0000:03:00.3: Refused to change power state, currently in D3 xhci_hcd 0000:03:00.3: pci_raw_set_power_state from 3 to 0 xhci_hcd 0000:03:00.3: enabling device (0000 -> 0002) xhci_hcd 0000:03:00.3: WARN: xHC restore state timeout xhci_hcd 0000:03:00.3: PCI post-resume error -110! xhci_hcd 0000:03:00.3: HC died; cleaning up So we just reproduced the same issue using runtime PM, without having to go through the whole suspend path. I guess that points towards a platform issue, although the weird thing is that Windows presumably does the D3-D0-D3 transition during suspend/resume and that appears to work fine. I'll report it to the vendor, but if you have any other debug ideas they would be much appreciated. Daniel
