* [PATCH v2 1/2] usb: core: Pair ports of different hubs through their connector
2026-11-12 8:26 [PATCH v2 0/2] usb: core: Pair ports of different host controllers through their connector Arun Iyengar via B4 Relay
@ 2026-11-12 8:26 ` Arun Iyengar via B4 Relay
2026-11-12 8:50 ` sashiko-bot
2026-11-12 8:26 ` [PATCH v2 2/2] usb: hub: Retry SuperSpeed for a device stuck on its USB 2.0 peer Arun Iyengar via B4 Relay
1 sibling, 1 reply; 5+ messages in thread
From: Arun Iyengar via B4 Relay @ 2026-11-12 8:26 UTC (permalink / raw)
To: Greg Kroah-Hartman, Rob Herring, Alan Stern
Cc: linux-usb, linux-kernel, Mathias Nyman, Chen-Yu Tsai,
Chen-Yu Tsai, Arun Iyengar
From: Arun Iyengar <aiyengar1990@gmail.com>
A USB 3 port is two ports to the USB core, a USB 2.0 one and a
SuperSpeed one, and the core pairs them as peers. Root hub ports are
paired with the same port number of the other root hub of the same
xHCI, unless ACPI gives their locations.
Some SoCs route the two halves of a connector to different host
controllers. On the Rockchip RK3588, USB 3.0 host 2 is SuperSpeed-only:
its own USB 2.0 root hub port is not wired to a PHY, and the connector's
USB 2.0 lines go to a separate EHCI instead. Default pairing then joins
the SuperSpeed port to a dead USB 2.0 port, and nothing knows about the
EHCI port that really shares the connector.
A usb-connector node describes its USB 2.0 data lines as graph port 0
and its SuperSpeed lanes as graph port 1. When a hub's or host
controller's graph links one of its ports to a connector whose other
half leads to a different hub or host controller, pair the port with
that one instead, and keep it out of the default pairing. Connectors
whose two halves end on the same node, like a Type-C connector on a
DWC3, keep the default pairing.
This lets the runtime PM rules for peers (keep the SuperSpeed port
powered while its USB 2.0 peer is) apply to such connectors too.
Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
---
drivers/usb/core/hub.h | 2 +
drivers/usb/core/of.c | 101 ++++++++++++++++++++++++++++++++++++++++++++++++
drivers/usb/core/port.c | 54 ++++++++++++++++++++++++--
include/linux/usb/of.h | 9 +++++
4 files changed, 162 insertions(+), 4 deletions(-)
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 9ebc5ef54a32..78382839be48 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -97,6 +97,7 @@ struct usb_hub {
* @usb3_lpm_u2_permit: whether USB3 U2 LPM is permitted.
* @early_stop: whether port initialization will be stopped earlier.
* @ignore_event: whether events of the port are ignored.
+ * @connector_peer: @peer is on another hub, paired through a connector.
*/
struct usb_port {
struct usb_device *child;
@@ -118,6 +119,7 @@ struct usb_port {
unsigned int is_superspeed:1;
unsigned int usb3_lpm_u1_permit:1;
unsigned int usb3_lpm_u2_permit:1;
+ unsigned int connector_peer:1;
};
#define to_usb_port(_dev) \
diff --git a/drivers/usb/core/of.c b/drivers/usb/core/of.c
index a6ee20d8774e..63cead74ae8e 100644
--- a/drivers/usb/core/of.c
+++ b/drivers/usb/core/of.c
@@ -145,6 +145,107 @@ enum usb_port_connect_type usb_of_get_connect_type(struct usb_device *hub, int p
}
EXPORT_SYMBOL_GPL(usb_of_get_connect_type);
+static bool usb_of_is_connector(const struct device_node *np)
+{
+ return of_device_is_compatible(np, "usb-a-connector") ||
+ of_device_is_compatible(np, "usb-b-connector") ||
+ of_device_is_compatible(np, "usb-c-connector");
+}
+
+/*
+ * Return the device node owning the far end of @con's endpoint on @con_port,
+ * and in @port1 the number of the port that endpoint belongs to.
+ */
+static struct device_node *usb_of_connector_remote(struct device_node *con,
+ u32 con_port, u32 *port1)
+{
+ struct device_node *ep, *remote;
+ struct of_endpoint endpoint;
+
+ ep = of_graph_get_endpoint_by_regs(con, con_port, -1);
+ if (!ep)
+ return NULL;
+
+ remote = of_graph_get_remote_endpoint(ep);
+ of_node_put(ep);
+ if (!remote)
+ return NULL;
+
+ if (of_graph_parse_endpoint(remote, &endpoint)) {
+ of_node_put(remote);
+ return NULL;
+ }
+ *port1 = endpoint.port;
+
+ ep = remote;
+ remote = of_graph_get_port_parent(ep);
+ of_node_put(ep);
+
+ return remote;
+}
+
+/**
+ * usb_of_get_connector_peer() - find a port's peer through its connector
+ * @hub: hub to which the port @port1 belongs
+ * @port1: one-based index of the port
+ * @superspeed: whether @hub is a SuperSpeed hub
+ * @peer_port1: returns the one-based index of the peer port
+ *
+ * A USB connector carries its USB 2.0 data lines on graph port 0 and its
+ * SuperSpeed lanes on graph port 1. Usually both reach the same hub or host
+ * controller, whose USB 2.0 and SuperSpeed ports are paired by default. Some
+ * SoCs instead route the two halves of a connector to different host
+ * controllers, for example a SuperSpeed-only xHCI paired with an EHCI. In that
+ * case the two ports can only be paired through the connector.
+ *
+ * Return: the device node of the hub or host controller providing the peer
+ * port, with its refcount incremented, if @port1 is the @superspeed half of a
+ * connector whose other half leads to a different node. NULL otherwise.
+ */
+struct device_node *usb_of_get_connector_peer(struct usb_device *hub,
+ int port1, bool superspeed,
+ u32 *peer_port1)
+{
+ struct device_node *np = hub->dev.of_node;
+ struct device_node *ep, *con, *remote, *peer = NULL;
+ u32 remote_port1;
+
+ if (!np || !of_graph_is_present(np))
+ return NULL;
+
+ ep = of_graph_get_endpoint_by_regs(np, port1, -1);
+ if (!ep)
+ return NULL;
+
+ con = of_graph_get_remote_port_parent(ep);
+ of_node_put(ep);
+ if (!con)
+ return NULL;
+
+ if (!usb_of_is_connector(con) || !of_device_is_available(con))
+ goto out;
+
+ /* The connector's half for our speed must lead back to this port */
+ remote = usb_of_connector_remote(con, superspeed ? 1 : 0, &remote_port1);
+ if (!remote)
+ goto out;
+ of_node_put(remote);
+ if (remote != np || remote_port1 != port1)
+ goto out;
+
+ /* Peers on the same node are paired without the connector's help */
+ peer = usb_of_connector_remote(con, superspeed ? 0 : 1, peer_port1);
+ if (peer && (peer == np || !*peer_port1 ||
+ !of_device_is_available(peer))) {
+ of_node_put(peer);
+ peer = NULL;
+ }
+out:
+ of_node_put(con);
+ return peer;
+}
+EXPORT_SYMBOL_GPL(usb_of_get_connector_peer);
+
/**
* usb_of_get_interface_node() - get a USB interface node
* @udev: USB device of interface
diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index b4452b665f59..1677118ae043 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -649,10 +649,39 @@ static int match_location(struct usb_device *peer_hdev, void *p)
return 0;
}
+struct usb_connector_peer {
+ struct usb_port *port_dev;
+ struct device_node *np;
+ u32 port1;
+};
+
+/*
+ * Check whether @peer_hdev is the hub that firmware describes as providing
+ * the other half of the port's connector, and link the two ports if it is.
+ */
+static int match_connector_peer(struct usb_device *peer_hdev, void *p)
+{
+ struct usb_connector_peer *cp = p;
+ struct usb_hub *peer_hub = usb_hub_to_struct_hub(peer_hdev);
+ struct usb_port *peer;
+
+ if (!peer_hub || peer_hdev->dev.of_node != cp->np ||
+ hub_is_superspeed(peer_hdev) == cp->port_dev->is_superspeed ||
+ cp->port1 > peer_hdev->maxchild)
+ return 0;
+
+ peer = peer_hub->ports[cp->port1 - 1];
+ if (!peer || peer->connect_type == USB_PORT_NOT_USED)
+ return 0;
+
+ link_peers_report(cp->port_dev, peer);
+ return 1; /* done */
+}
+
/*
* Find the peer port either via explicit platform firmware "location"
- * data, the peer hcd for root hubs, or the upstream peer relationship
- * for all other hubs.
+ * data, a connector described in the device tree, the peer hcd for root
+ * hubs, or the upstream peer relationship for all other hubs.
*/
static void find_and_link_peer(struct usb_hub *hub, int port1)
{
@@ -660,6 +689,7 @@ static void find_and_link_peer(struct usb_hub *hub, int port1)
struct usb_device *hdev = hub->hdev;
struct usb_device *peer_hdev;
struct usb_hub *peer_hub;
+ struct usb_connector_peer cp;
/*
* If location data is available then we can only peer this port
@@ -671,7 +701,23 @@ static void find_and_link_peer(struct usb_hub *hub, int port1)
/* we link the peer in match_location() if found */
usb_for_each_dev(port_dev, match_location);
return;
- } else if (!hdev->parent) {
+ }
+
+ /*
+ * If a connector routes the two halves of this port to different
+ * hubs or host controllers, the connector alone decides the peer.
+ */
+ cp.np = usb_of_get_connector_peer(hdev, port1,
+ port_dev->is_superspeed, &cp.port1);
+ if (cp.np) {
+ cp.port_dev = port_dev;
+ port_dev->connector_peer = 1;
+ usb_for_each_dev(&cp, match_connector_peer);
+ of_node_put(cp.np);
+ return;
+ }
+
+ if (!hdev->parent) {
struct usb_hcd *hcd = bus_to_hcd(hdev->bus);
struct usb_hcd *peer_hcd = hcd->shared_hcd;
@@ -703,7 +749,7 @@ static void find_and_link_peer(struct usb_hub *hub, int port1)
* does not have location data
*/
peer = peer_hub->ports[port1 - 1];
- if (peer && peer->location == 0)
+ if (peer && peer->location == 0 && !peer->connector_peer)
link_peers_report(port_dev, peer);
}
diff --git a/include/linux/usb/of.h b/include/linux/usb/of.h
index de42f14bd280..cfcfa26e7c69 100644
--- a/include/linux/usb/of.h
+++ b/include/linux/usb/of.h
@@ -20,6 +20,9 @@ int of_usb_update_otg_caps(struct device_node *np,
struct usb_otg_caps *otg_caps);
enum usb_port_connect_type usb_of_get_connect_type(struct usb_device *hub, int port1);
struct device_node *usb_of_get_device_node(struct usb_device *hub, int port1);
+struct device_node *usb_of_get_connector_peer(struct usb_device *hub,
+ int port1, bool superspeed,
+ u32 *peer_port1);
bool usb_of_has_combined_node(struct usb_device *udev);
struct device_node *usb_of_get_interface_node(struct usb_device *udev,
u8 config, u8 ifnum);
@@ -49,6 +52,12 @@ usb_of_get_device_node(struct usb_device *hub, int port1)
{
return NULL;
}
+static inline struct device_node *
+usb_of_get_connector_peer(struct usb_device *hub, int port1, bool superspeed,
+ u32 *peer_port1)
+{
+ return NULL;
+}
static inline bool usb_of_has_combined_node(struct usb_device *udev)
{
return false;
--
2.55.0
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v2 2/2] usb: hub: Retry SuperSpeed for a device stuck on its USB 2.0 peer
2026-11-12 8:26 [PATCH v2 0/2] usb: core: Pair ports of different host controllers through their connector Arun Iyengar via B4 Relay
2026-11-12 8:26 ` [PATCH v2 1/2] usb: core: Pair ports of different hubs " Arun Iyengar via B4 Relay
@ 2026-11-12 8:26 ` Arun Iyengar via B4 Relay
2026-11-12 8:42 ` sashiko-bot
1 sibling, 1 reply; 5+ messages in thread
From: Arun Iyengar via B4 Relay @ 2026-11-12 8:26 UTC (permalink / raw)
To: Greg Kroah-Hartman, Rob Herring, Alan Stern
Cc: linux-usb, linux-kernel, Mathias Nyman, Chen-Yu Tsai,
Chen-Yu Tsai, Arun Iyengar
From: Arun Iyengar <aiyengar1990@gmail.com>
A SuperSpeed device looks for a SuperSpeed link first when it sees
VBUS, and connects at high speed when the link doesn't come up. It
looks again only when VBUS is cycled or after a USB 2.0 bus reset.
When a connector's two halves belong to different host controllers,
the USB 2.0 host can start first. On the Orange Pi 5 (RK3588S), whose
USB 3 Type-A port has VBUS on from power-up, a USB 3 flash drive
plugged in at boot was reset by the EHCI about 10 ms before the
SuperSpeed-only xHCI registered, so it came up at 480 Mb/s on the EHCI
in every one of 6 boots, while plugging it in after boot gave
5 Gb/s. It stays at high speed until it is unplugged.
When a SuperSpeed root hub with ports paired through a connector to a
root hub port of another host controller has started, check those
USB 2.0 peers. If a SuperSpeed-capable device that is not a hub is
connected at high speed there, reset it once, so that it can connect
at SuperSpeed now that the link can train. Lock the peer root hub
first, so an enumeration that is under way completes before the check.
A device that still can't train its SuperSpeed link stays connected at
high speed after that one reset.
Only the start of the root hub does this, not a resume or a reset of
it: a device that is suspended with the system can't be reset, and the
problem is the start-up order of the two controllers. Hubs are left
alone, because the USB 2.0 half of a USB 3 hub stays at high speed next
to its SuperSpeed half. The work runs on the freezable hub_wq, holds a
runtime PM reference on the SuperSpeed hub and is cancelled when the
hub is quiesced.
Signed-off-by: Arun Iyengar <aiyengar1990@gmail.com>
---
drivers/usb/core/hub.c | 113 +++++++++++++++++++++++++++++++++++++++++++++++++
drivers/usb/core/hub.h | 1 +
2 files changed, 114 insertions(+)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 199d3f535a89..eaa2a5b6aba0 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -1076,6 +1076,109 @@ int usb_remove_device(struct usb_device *udev)
return 0;
}
+/*
+ * A SuperSpeed root hub port can be paired through a connector with a USB 2.0
+ * root hub port of another host controller. With VBUS always on, a device
+ * present at boot looks for a SuperSpeed link while the SuperSpeed host is
+ * still down, gives up and connects at high speed to the USB 2.0 host. It
+ * only tries SuperSpeed again after VBUS is cycled or after a USB 2.0 bus
+ * reset, so reset it once when the SuperSpeed root hub has started.
+ */
+static void hub_reset_peer_child(struct usb_device *peer_hdev, int peer_port1)
+{
+ struct usb_hub *peer_hub;
+ struct usb_device *udev;
+
+ /* Wait for an enumeration in progress on the peer port to finish */
+ usb_lock_device(peer_hdev);
+ peer_hub = usb_hub_to_struct_hub(peer_hdev);
+ if (!peer_hub || peer_port1 > peer_hdev->maxchild)
+ goto out;
+
+ udev = peer_hub->ports[peer_port1 - 1]->child;
+ if (!udev || udev->speed != USB_SPEED_HIGH)
+ goto out;
+
+ /*
+ * The USB 2.0 half of a USB 3 hub stays at high speed next to its
+ * SuperSpeed half, and resetting it would disconnect its children.
+ */
+ if (udev->descriptor.bDeviceClass == USB_CLASS_HUB)
+ goto out;
+
+ usb_lock_device(udev);
+ if (udev->state != USB_STATE_NOTATTACHED &&
+ udev->bos && udev->bos->ss_cap) {
+ dev_info(&udev->dev,
+ "SuperSpeed peer port available, resetting\n");
+ usb_reset_device(udev);
+ }
+ usb_unlock_device(udev);
+out:
+ usb_unlock_device(peer_hdev);
+}
+
+static void hub_peer_reset_work(struct work_struct *ws)
+{
+ struct usb_hub *hub = container_of(ws, struct usb_hub, peer_reset_work);
+ struct usb_device *hdev = hub->hdev;
+ int port1;
+
+ for (port1 = 1; ; port1++) {
+ struct usb_device *peer_hdev = NULL;
+ struct usb_port *port_dev;
+ int peer_port1 = 0;
+
+ mutex_lock(&usb_port_peer_mutex);
+ if (port1 > hdev->maxchild) {
+ mutex_unlock(&usb_port_peer_mutex);
+ break;
+ }
+ port_dev = hub->ports[port1 - 1];
+ if (port_dev->connector_peer && port_dev->peer) {
+ peer_hdev = to_usb_device(port_dev->peer->dev.parent->parent);
+ peer_port1 = port_dev->peer->portnum;
+ /* Only root hub ports of another host controller */
+ if (peer_hdev->parent ||
+ peer_hdev->bus->controller == hdev->bus->controller)
+ peer_hdev = NULL;
+ else
+ usb_get_dev(peer_hdev);
+ }
+ mutex_unlock(&usb_port_peer_mutex);
+
+ if (peer_hdev) {
+ hub_reset_peer_child(peer_hdev, peer_port1);
+ usb_put_dev(peer_hdev);
+ }
+ }
+
+ usb_autopm_put_interface_async(to_usb_interface(hub->intfdev));
+ hub_put(hub);
+}
+
+/* Called when a SuperSpeed root hub has started */
+static void hub_queue_peer_reset(struct usb_hub *hub)
+{
+ struct usb_interface *intf = to_usb_interface(hub->intfdev);
+ int port1;
+
+ for (port1 = 1; port1 <= hub->hdev->maxchild; port1++) {
+ if (hub->ports[port1 - 1]->connector_peer)
+ break;
+ }
+ if (port1 > hub->hdev->maxchild)
+ return;
+
+ /* Keep the hub active until the work is done; hub_quiesce() cancels it */
+ usb_autopm_get_interface_no_resume(intf);
+ hub_get(hub);
+ if (!queue_work(hub_wq, &hub->peer_reset_work)) {
+ usb_autopm_put_interface_async(intf);
+ hub_put(hub);
+ }
+}
+
enum hub_activation_type {
HUB_INIT, HUB_INIT2, HUB_INIT3, /* INITs must come first */
HUB_POST_RESET, HUB_RESUME, HUB_RESET_RESUME,
@@ -1346,6 +1449,11 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
/* Scan all ports that need attention */
kick_hub_wq(hub);
+
+ /* Let devices stuck at high speed on a connector peer move over */
+ if (!hdev->parent && hub_is_superspeed(hdev) &&
+ (type == HUB_INIT2 || type == HUB_INIT3))
+ hub_queue_peer_reset(hub);
abort:
if (type == HUB_INIT2 || type == HUB_INIT3) {
/* Allow autosuspend if it was suppressed */
@@ -1419,6 +1527,10 @@ static void hub_quiesce(struct usb_hub *hub, enum hub_quiescing_type type)
/* Stop hub_wq and related activity */
timer_delete_sync(&hub->irq_urb_retry);
flush_delayed_work(&hub->post_resume_work);
+ if (cancel_work_sync(&hub->peer_reset_work)) {
+ usb_autopm_put_interface_no_suspend(to_usb_interface(hub->intfdev));
+ hub_put(hub);
+ }
usb_kill_urb(hub->urb);
if (hub->has_indicators)
cancel_delayed_work_sync(&hub->leds);
@@ -1978,6 +2090,7 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
INIT_DELAYED_WORK(&hub->leds, led_work);
INIT_DELAYED_WORK(&hub->init_work, NULL);
INIT_DELAYED_WORK(&hub->post_resume_work, hub_post_resume);
+ INIT_WORK(&hub->peer_reset_work, hub_peer_reset_work);
INIT_WORK(&hub->events, hub_event);
INIT_LIST_HEAD(&hub->onboard_devs);
spin_lock_init(&hub->irq_urb_lock);
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 78382839be48..edce19d7bf13 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -71,6 +71,7 @@ struct usb_hub {
struct delayed_work leds;
struct delayed_work init_work;
struct delayed_work post_resume_work;
+ struct work_struct peer_reset_work;
struct work_struct events;
spinlock_t irq_urb_lock;
struct timer_list irq_urb_retry;
--
2.55.0
^ permalink raw reply related [flat|nested] 5+ messages in thread