usb_add_config(9)

💅 usb_add_config — like, the Kernel API Manual page for usb_add_config(9), bestie

okay so real talk, this is section 9 of the Kernel API Manual and it's about usb_add_config(9). In the NAME section it literally just says: add a configuration to a device. That's the whole vibe. ✨

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✨ SYNOPSIS ✨

int usb_add_config (struct usb_composite_dev *cdev , struct
usb_configuration *config , int (*bind)(struct usb_configuration *) );

yes that function pointer is doing the absolute most, we love to see it 🫶

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🎀 ARGUMENTS 🎀

• cdev — this one wraps the USB gadget. it's giving "the whole container of the whole situation" energy 💅
• config — the configuration itself, and heads up: it needs bConfigurationValue already assigned before you hand it over. no coin flips, assign it 😭
• bind — the configuration's bind function. this is the callback that actually makes the magic happen ⭐

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🧚 CONTEXT 🧚

single threaded during gadget setup. so like, chill, nobody's racing you here. one thing at a time, bestie 🦋

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👑 DESCRIPTION 👑

So here's the tea: one of the main tasks of a composite bind routine is to add each of the configurations it supports, and this routine is literally the one you use to do that. main character function, no cap 🔥

This function returns the value of the configuration's bind — which is zero for success, else a negative errno value. Love that for us when it's zero 💖

And binding configurations is not just vibing, okay? it assigns global resources including string IDs, plus per-configuration resources such as interface IDs and endpoints. so it's doing a lot of very real work behind the scenes 🌸

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🌈 SEE ALSO 🌈

• Kernel file ./drivers/usb/gadget/composite.c
• struct usb_os_string(9)
• function_descriptors(9)
• next_desc(9)
• config_ep_by_speed_and_alt(9)
• config_ep_by_speed(9)
• usb_add_function(9)
• usb_function_deactivate(9)
• usb_function_activate(9)
• usb_interface_id(9)
• usb_func_wakeup(9)
• bos_desc(9)
• usb_string_id(9)
• usb_string_ids_tab(9)
• usb_gstrings_attach(9)
• usb_string_ids_n(9)
• usb_composite_probe(9)
• usb_composite_unregister(9)
• usb_composite_setup_continue(9)

like, that's a whole friend group right there, go read the whole squad 🫶

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ngl bestie, the one thing to remember: bConfigurationValue has to be set on config before you call this, and the return value comes straight from your bind. zero = slay, negative errno = not slay 💀

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that's the whole page!! sourced from ./drivers/usb/gadget, dated October 2026, and it's usb_add_config(9) the whole way through — periodt 🎀✨💜