usb_udc_vbus_handler(9)

✨ NAME ✨

okay so bestie, welcome to the page for usb_udc_vbus_handler(9) from the Kernel API Manual 🫶 This is the function that updates the udc core vbus status, and try to connect or disconnect gadget. That's the name-section tea ☕.

📜 SYNOPSIS 📜

void usb_udc_vbus_handler (struct usb_gadget *gadget , bool status );

yep, it returns void — nothing comes back out, bestie 💅.

🎀 ARGUMENTS 🎀

• gadget — the gadget where the vbus change occurs. That's the one getting the vbus update.
• status — the vbus status. That's it, that's the argument 🌸.

💅 DESCRIPTION 💅

The udc driver calls it when it wants to connect or disconnect the gadget according to vbus status. Simple vibe on the surface, right? ✨

Now the important context check, because this is where people get got 💀 This function can be invoked from interrupt context by irq handlers of the gadget drivers. However, usb_udc_connect_control has to run in non-atomic context due to the following:

1. Some of the gadget driver implementations expect the ->pullup callback to be invoked in non-atomic context.
2. usb_gadget_disconnect acquires udc_lock, which is a mutex.

Hence, the invocation of usb_udc_connect_control is offloaded to a workqueue. So yeah: interrupt context for this function? fine. usb_udc_connect_control in atomic context? absolutely not, bestie 😭 context rules ate here.

🌈 SEE ALSO 🌈

go read these too, iykyk 👑:

• Kernel file ./drivers/usb/gadget/udc/core.c, struct usb_udc(9)
• usb_ep_set_maxpacket_limit(9), usb_ep_enable(9), usb_ep_disable(9)
• usb_ep_alloc_request(9), usb_ep_free_request(9), usb_ep_queue(9), usb_ep_dequeue(9)
• usb_ep_set_halt(9), usb_ep_clear_halt(9), usb_ep_set_wedge(9), usb_ep_fifo_status(9), usb_ep_fifo_flush(9)
• usb_gadget_frame_number(9), usb_gadget_wakeup(9), usb_gadget_set_remote_wakeup(9), usb_gadget_set_selfpowered(9), usb_gadget_clear_selfpowered(9)
• usb_gadget_vbus_connect(9), usb_gadget_vbus_draw(9), usb_gadget_vbus_disconnect(9), usb_gadget_connect(9), usb_gadget_disconnect(9)
• usb_gadget_deactivate(9), usb_gadget_activate(9), usb_gadget_giveback_request(9), gadget_find_ep_by_name(9)
• usb_gadget_check_config(9), usb_gadget_udc_reset(9), usb_gadget_udc_start_locked(9), usb_gadget_udc_stop_locked(9), usb_gadget_udc_set_speed(9)
• usb_gadget_enable_async_callbacks(9), usb_gadget_disable_async_callbacks(9), usb_udc_release(9)
• usb_initialize_gadget(9), usb_add_gadget(9), usb_add_gadget_udc_release(9), usb_get_gadget_udc_name(9)
• usb_add_gadget_udc(9), usb_del_gadget(9), usb_del_gadget_udc(9)

mwah 💋 that's the page! source/version: ./drivers/usb/gadget/udc · date: October 2026 · page: usb_udc_vbus_handler(9) 🫶