STRUCT USB_ROLE_SWITCH_DESC(9)

✨ NAME ✨

struct usb_role_switch_desc — the USB Role Switch Descriptor 💅

okay so basically this is a kernel API manual page, bestie — it's from the struct usb_role_switch_desc(9) family, and it's literally just describing one lil struct and every field inside it. no cap, that's the whole vibe. 🎀

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🦋 SYNOPSIS 🦋

here's the whole thing, character for character, so you can copy it and slay:

struct usb_role_switch_desc {
    struct fwnode_handle *fwnode;
    struct device *usb2_port;
    struct device *usb3_port;
    struct device *udc;
    usb_role_switch_set_t set;
    usb_role_switch_get_t get;
    bool allow_userspace_control;
    void *driver_data;
    const char *name;
 };

she's giving "small struct, big responsibilities" honestly 😭

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🌸 Members 🌸

okay now the main character energy — every single field, one by one, no skips:

• fwnode — the device node that gets associated with the role switch 🔗
• usb2_port — optional reference to the host controller port device (USB2) 🍓
• usb3_port — optional reference to the host controller port device (USB3) 🍓
• udc — optional reference to the peripheral controller device 🌈
• set — the callback for setting the role 🔥
• get — the callback for getting the role (optional, king) 👑
• allow_userspace_control — if true, userspace may change the role through sysfs 👀
• driver_data — private data pointer, mind your business 🫶
• name — name for the switch (optional) 🎀

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💜 Description 💜

so like, the way this works: usb2_port and usb3_port will point to the USB host port, and udc points to the USB device controller behind the USB connector with the role switch. that's the picture, periodt. ✨

⚠️ okay this is the important bit, bestie, don't skip it: if usb2_port, usb3_port and udc are included in the description, the reference count for them should be incremented by the caller of usb_role_switch_register before registering the switch. the way that's not optional… yeah. do it in that order fr fr 🫡

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🧚 SEE ALSO 🧚

• kernel file ./include/linux/usb/role.h — go read it, iykyk 📖

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and that's a wrap, bestie!! 🌟 this page lives in ./include/linux/usb, dated October 2026, and it's literally the struct usb_role_switch_desc(9) page — iconic, ate, no crumbs. see you in the group chat 💖🦋✨