[PATCH v4 1/5] usb: port: track the disabled state

Marco Felsch
2025-09-11T20:22:56Z

The disable state isn't tracked at the moment, instead the state is
directly passed to the hub driver. Change this behavior to only trigger
the hub if a state change happened. Exit early in case of no state
changes but don't return an error.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
---
drivers/usb/core/hub.h | 2 ++
drivers/usb/core/port.c | 6 ++++++
2 files changed, 8 insertions(+)

diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index 9ebc5ef54a325d63e01b0deb59a1853d2b13c8d5..297adf2c6078809ca582104f228e5222c464f999 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.
+ * @disabled: whether the port is disabled
*/
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 disabled:1;
};

#define to_usb_port(_dev) \
diff --git a/drivers/usb/core/port.c b/drivers/usb/core/port.c
index f54198171b6a3fb49c5f74f4a8a303b422d099eb..cae08a9a71e65c42fb9a8f5369060bd82b8daebb 100644
--- a/drivers/usb/core/port.c
+++ b/drivers/usb/core/port.c
@@ -117,6 +117,10 @@ static ssize_t disable_store(struct device *dev, struct device_attribute *attr,
if (rc)
return rc;

+ /* Early quit if no change was detected */
+ if (port_dev->disabled == disabled)
+ return count;
+
hub_get(hub);
rc = usb_autopm_get_interface(intf);
if (rc < 0)
@@ -148,6 +152,8 @@ static ssize_t disable_store(struct device *dev, struct device_attribute *attr,
usb_clear_port_feature(hdev, port1, USB_PORT_FEAT_C_ENABLE);
}

+ port_dev->disabled = disabled;
+
if (!rc)
rc = count;

--
2.47.3