Messages in this thread |  | | Date | Thu, 7 May 2026 15:48:27 +0300 | | Subject | Re: [PATCH 1/2] usb: host: xhci: Allow non-Intel usb_link_tunnel_mode reporting | | From | Mathias Nyman <> |
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On 5/7/26 13:40, Konrad Dybcio wrote: > On 5/5/26 2:14 PM, Mika Westerberg wrote: >> Hi, >> >> On Tue, May 05, 2026 at 10:55:04AM +0200, Konrad Dybcio wrote: >>> From: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com> >>> >>> The Thunderbolt framework relies on the USB core to create device links >>> for tunneled ports, so that the USB3 controller is only kept >>> runtime-resumed for the duration of the tunneling. >>> >>> Currently, retrieving that information is only possibe on Intel XHCI >>> hosts, through a vendor-specific capability. Extend xhci-plat to allow >>> plumbing a custom one. >>> >>> Signed-off-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com> >>> --- >>> drivers/usb/host/xhci-hub.c | 4 ++-- >>> drivers/usb/host/xhci-plat.c | 2 ++ >>> drivers/usb/host/xhci-plat.h | 1 + >>> drivers/usb/host/xhci.c | 6 +++++- >>> drivers/usb/host/xhci.h | 5 ++++- >>> 5 files changed, 14 insertions(+), 4 deletions(-) >>> >>> diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c >>> index bacd0ddd0d09..09e5da912066 100644 >>> --- a/drivers/usb/host/xhci-hub.c >>> +++ b/drivers/usb/host/xhci-hub.c >>> @@ -750,7 +750,7 @@ static int xhci_exit_test_mode(struct xhci_hcd *xhci) >>> } >>> >>> /** >>> - * xhci_port_is_tunneled() - Check if USB3 connection is tunneled over USB4 >>> + * xhci_port_tunnel_mode() - Check if USB3 connection is tunneled over USB4 >>> * @xhci: xhci host controller >>> * @port: USB3 port to be checked. >>> * >>> @@ -764,7 +764,7 @@ static int xhci_exit_test_mode(struct xhci_hcd *xhci) >>> * detecting USB3 over USB4 tunnels. USB_LINK_NATIVE or USB_LINK_TUNNELED >>> * otherwise. >>> */ >>> -enum usb_link_tunnel_mode xhci_port_is_tunneled(struct xhci_hcd *xhci, >>> +enum usb_link_tunnel_mode xhci_port_tunnel_mode(struct xhci_hcd *xhci, >>> struct xhci_port *port) >> >> I'm wondering if this could be: >> >> bool xhci_port_is_tunneled() >> >> becase if I understand correctly that's the only information we need e.g is >> it going over tunnel or not. > > It was originally introduced as a tristate enum in: > > f46a6e165197 ("usb: Add tunnel_mode parameter to usb device structure") > > but the usefulness of USB_LINK_UNKNOWN is limited to a dev_dbg() print.. > I don't really have strong opinions either way >
Tunnel detection can be tried other ways if state is USB_LINK_UNKNOWN.
For example usb-acpi.c will try to create a tunnel if all the ACPI entries exists that indicate a tunnel, but the current xHC doesn't support tunnel detection.
usb_acpi_find_companion_for_device(struct usb_device *udev) { ...
/* Tunneled USB3 devices depend on USB4 Host Interface, set device link to it */ if (udev->speed >= USB_SPEED_SUPER && udev->tunnel_mode != USB_LINK_NATIVE) usb_acpi_add_usb4_devlink(udev); }
-Mathias
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