ENUM ATCPHY_PIPEHANDLER_STATE(9)

💅 enum atcphy_pipehandler_state — kernel API manual, bestie edition

okay so this is from the Kernel API Manual, and the page is literally called enum atcphy_pipehandler_state(9). iconic. it's all about the states of the PIPE mux interface — yeah, the "pipehandler" ✨

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🌸 NAME 🌸

enum atcphy_pipehandler_state — the states of the PIPE mux interface (the "pipehandler", iykyk) 🎀

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🦋 SYNOPSIS 🦋

enum atcphy_pipehandler_state {
    ATCPHY_PIPEHANDLER_STATE_DUMMY ,
    ATCPHY_PIPEHANDLER_STATE_USB3 ,
    ATCPHY_PIPEHANDLER_STATE_USB4

};

like, that's the whole squad. three members, no more, no less 💅

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✨ Constants ✨

• ATCPHY_PIPEHANDLER_STATE_DUMMY — the "Dummy PHY" state, which disables USB3 so you're on USB2 only 🫶
• ATCPHY_PIPEHANDLER_STATE_USB3 — USB3 is directly connected to the Type-C port, no middleman 🌈
• ATCPHY_PIPEHANDLER_STATE_USB4 — USB3 is tunneled via USB4/Thunderbolt, main character energy 🔥

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👑 Description 👑

so here's the vibe check: DWC3's USB3 PIPE interface is connected to a multiplexer inside this PHY, and that mux can switch between three whole states 👀

• a dummy state — this one effectively disables any USB3 support and falls back to USB2 only operation via the separate ULPI interface 😭
• a USB3 state — for regular USB3 or USB3+DisplayPort operation 🎀
• a USB4 state — for USB3 tunneled via USB4/Thunderbolt ⭐

that's it. that's the mux. slay.

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🔍 SEE ALSO 🔍

• Kernel file ./drivers/phy/apple/atc.c — enum atcphy_mode(9), struct apple_atcphy(9) 💜

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bestie fr fr read the actual source before you poke at it, k? ./drivers/phy/apple is where the magic lives 🙈

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and that's the page, periodt 💅 this cutie came out of ./drivers/phy/apple, dated October 2026, and it's filed under enum atcphy...andler_state(9) in the Kernel API Manual — go off, kernel docs 🌸🫶