The relationship between a USB4 Host Interface providing USB3 tunnels,
and tunneled USB3 devices is not represented in device hierarchy.
This caused issues with power managment as devices may suspend and
resume in incorrect order.
A device link between the USB4 Host Interface and the USB3 xHCI was
originally added to solve this, preventing the USB4 Host Interface from
suspending if the USB3 xHCI Host was still active.
This unfortunately also prevents USB4 Host Interface from suspending even
if the USB3 xHCI Host is only serving native non-tunneled USB devices.
Improve the current powermanagement situation by creating device links
directly from tunneled USB3 devices to the USB4 Host Interface they depend
on instead of a device link between the hosts.
This way USB4 host may suspend when the last tunneled device is
disconnected.
Intel xHCI hosts are capable of reporting if connected USB3 devices are
tunneled via vendor specific capabilities.
Use this until a standard way is available.
v2:
Create device link by default if xHC host is not capable of tunnel
detection but the USB3 ports have tunnel capability reported in ACPI
_DSD object
Mathias Nyman (4):
xhci: Add USB4 tunnel detection for USB3 devices on Intel hosts
usb: Add tunnel_mode parameter to usb device structure
usb: acpi: add device link between tunneled USB3 device and USB4 Host
Interface
thunderbolt: Don't create device link from USB4 Host Interface to USB3
xHC host
drivers/thunderbolt/acpi.c | 40 ++++++------------------
drivers/usb/core/usb-acpi.c | 53 ++++++++++++++++++++++++++++++++
drivers/usb/host/xhci-ext-caps.h | 5 +++
drivers/usb/host/xhci-hub.c | 36 ++++++++++++++++++++++
drivers/usb/host/xhci.c | 14 +++++++++
drivers/usb/host/xhci.h | 3 +-
include/linux/usb.h | 8 +++++
7 files changed, 128 insertions(+), 31 deletions(-)
--
2.25.1
