config_ep_by_speed(9)

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

okay so real talk, this is config_ep_by_speed(9) from the Kernel API Manual and it's honestly such a main character function. it sets up your endpoint for whatever speed your gadget is doing, no cap. let's get into it 🎀

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✨ NAME ✨

config_ep_by_speed — configures the given endpoint according to gadget speed. that's it, that's the vibe. 🦋

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🌸 SYNOPSIS 🌸

int config_ep_by_speed (struct usb_gadget *g , struct usb_function *f ,
       struct usb_ep *_ep );

literally the whole signature, copied exactly, don't come for me 💅

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💖 ARGUMENTS 💖

• g — pointer to the gadget. yeah, the whole gadget. iconic.
• f — the usb function. the function in question, the one doing the work 🫶
• _ep — the endpoint to configure. this is the one getting its glow-up ✨

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🌈 RETURN 🌈

an error code, bestie. and 0 on success — that's the one you want, the 0, the good ending 👑

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🔥 DESCRIPTION 🔥

okay so here's the tea ☕ — this function chooses the right descriptors for a given endpoint according to gadget speed, and then saves that in the endpoint desc field. like it's matching the outfit to the occasion, iykyk.

and if the endpoint already has a descriptor assigned to it? not me just overwriting it 🙈 — it overwrites it with the currently corresponding descriptor. rude but efficient. periodt.

also the endpoint maxpacket field gets updated according to the chosen descriptor. so everything stays consistent, fr fr. 💜

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⭐ NOTE ⭐

the supplied function should hold all the descriptors for supported speeds. like, all of them. don't show up with a partial wardrobe and expect this to slay 😭

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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)
• usb_add_function(9)
• usb_function_deactivate(9)
• usb_function_activate(9)
• usb_interface_id(9)
• usb_func_wakeup(9)
• bos_desc(9)
• usb_add_config(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)

that's the whole friend group, go say hi 🫶💖

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ngl if you skip the NOTE section you're gonna have a bad time. just saying. 💀

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and that's the page!! this little gem lives in ./drivers/usb/gadget, dated October 2026 💫 sending you off with a cute lil sign-off — mwah, go configure those endpoints, bestie 🎀🌸✨