I'm unable to use any USB devices connected to an XHCI controller to resume from S3 standby, as something causes all connected devices to disconnect just prior to entering standby, as per the output of dmesg.
I've traced the relevant sections in the southbridge and ACPI source for my device (a haswell-based ChromeOS device with an Intel lynxpoint southbridge), but have been unable to find the culprit.
CONFIG_FINALIZE_USB_ROUTE_XHCI is set, as this device only has USB3 ports (4x), but having it set either way doesn't make a difference. The usb_xhci_sleep_prepare() call doesn't seem to be the culprit, as commenting it out has no (positive) effect.
Resuming via the power switch or wake on lan work perfectly, so it's not a general resuming issue.
Appreciate any pointers on how to proceed