STRUCT USB_EP_CAPS(9)

💅 struct usb_ep_caps(9) — like, the whole vibe of an endpoint's abilities, bestie

okay so this is a page from the Kernel API Manual and it's genuinely so iconic — it's the lil' struct that tells you what a USB endpoint can and can't do. think of it as an endpoint's resume, but make it six bitfields. no cap. 🎀

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✨ NAME ✨

struct usb_ep_caps — the description of endpoint capabilities. that's it, that's the whole job, and she ate. 💖

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🦋 SYNOPSIS 🦋

here's the struct in all her glory, copy it exactly pls, don't touch a single character:

struct usb_ep_caps {
    unsigned type_control:1;
    unsigned type_iso:1;
    unsigned type_bulk:1;
    unsigned type_int:1;
    unsigned dir_in:1;
    unsigned dir_out:1;
 };

look at those :1 bitfields. frugal. efficient. main character energy. ✨

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🌸 Members 🌸

every single one, bestie, no skipping:

• type_control — this endpoint supports the control type. but important: it's reserved for ep0, so don't be out here claiming it for anything else. 🙈
• type_iso — this endpoint supports isochronous transfers.
• type_bulk — this endpoint supports bulk transfers.
• type_int — this endpoint supports interrupt transfers.
• dir_in — this endpoint supports the IN direction.
• dir_out — this endpoint supports the OUT direction.

so basically five of these are "can she do the thing: yes/no" and two are "which way does the data flow". vibe check complete. 🫶

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🌈 SEE ALSO 🌈

these live in the kernel file ./include/linux/usb/gadget.h and honestly the whole friend group is here, all of them, iykyk:

• struct usb_request(9)
• struct usb_ep(9)
• free_usb_request(9)
• struct usb_gadget(9)
• usb_ep_align(9)
• usb_ep_align_maybe(9)
• gadget_is_altset_supported(9)
• gadget_is_stall_supported(9)
• gadget_is_zlp_supported(9)
• gadget_avoids_skb_reserve(9)
• gadget_is_dualspeed(9)
• gadget_is_superspeed(9)
• gadget_is_superspeed_plus(9)
• gadget_is_otg(9)
• struct usb_gadget_driver(9)
• usb_gadget_register_driver_owner(9)
• usb_gadget_unregister_driver(9)
• struct usb_string(9)
• struct usb_gadget_strings(9)
• usb_free_descriptors(9)

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lowkey reminder: type_control is reserved for ep0. that's not me being dramatic, that's just the rule. 💀

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and that's the page!! shoutout to ./include/linux/usb for hosting this masterpiece, dated October 2026, filed under struct usb_ep_caps(9). periodt. 👑💜