tb_tunnel_alloc_dp(9)

💅 tb_tunnel_alloc_dp — kernel API manual, bestie edition 💅

okay so this is tb_tunnel_alloc_dp(9) from the kernel API manual and honestly? it's giving main character energy for your Thunderbolt stack 🌈✨

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✨ NAME ✨

tb_tunnel_alloc_dp — allocate a Display Port tunnel 🖥️💖 like literally it makes you a DP tunnel, no cap

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🎀 SYNOPSIS 🎀

struct tb_tunnel * tb_tunnel_alloc_dp (struct tb *tb , struct tb_port
*in , struct tb_port *out , int link_nr , int max_up , int max_down ,
void (*callback)(struct tb_tunnel *, void *) , void *callback_data );

that's the whole signature, copy it exactly girlies, character for character, don't be out here renaming params 💀

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🦋 ARGUMENTS 🦋

• tb — pointer to the domain structure. the domain. the whole vibe container 👑
• in — the DP in adapter port 🫶
• out — the DP out adapter port 🫶
• link_nr — your preferred lane adapter, but ONLY when the link is not bonded. read that again. when the link is not bonded 🎀
• max_up — maximum available upstream bandwidth for the DP tunnel. and if it's 0, that means no available bandwidth. yes literally zero means none, don't come for me 😭
• max_down — maximum available downstream bandwidth for the DP tunnel. also 0 if no available bandwidth. same rules, opposite direction 💅
• callback — the callback that gets called when the DP tunnel is fully activated (or when there's an error). she shows up either way, iconic 🔥
• callback_data — data for callback. the little snack you hand her 🍓

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🌸 DESCRIPTION 🌸

So what she does: allocates a tunnel between in and out that is capable of tunneling Display Port traffic. that's the whole job, and she ate 💅✨

The callback is called after tb_tunnel_activate — once the tunnel has been fully activated. and bestie, it can call tb_tunnel_is_active to check if activation was actually successful (or if it returns false, well… there was some sort of issue 🙈😭).

⚠️ important detail, do NOT skip: the callback is called without tb->lock held. like the lock is not held. fr fr, internalize this 🔒❌

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⭐ RETURN ⭐

Pointer to struct tb_tunnel, or NULL in case of failure. that's it, that's the deal 🎀

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💜 SEE ALSO 💜

Kernel file ./drivers/thunderbolt/tunnel.c and honestly the whole friend group:

tb_available_credits(9), tb_tunnel_event(9), tb_tunnel_discover_pci(9), tb_tunnel_alloc_pci(9), tb_tunnel_reserved_pci(9), tb_dp_bandwidth_mode_maximum_bandwidth(9), tb_tunnel_discover_dp(9), tb_tunnel_alloc_dma(9), tb_tunnel_match_dma(9), tb_tunnel_discover_usb3(9), tb_tunnel_alloc_usb3(9), tb_tunnel_is_invalid(9), tb_tunnel_activate(9), tb_tunnel_deactivate(9), tb_tunnel_port_on_path(9), tb_tunnel_maximum_bandwidth(9), tb_tunnel_allocated_bandwidth(9), tb_tunnel_alloc_bandwidth(9), tb_tunnel_consumed_bandwidth(9), tb_tunnel_release_unused_bandwidth(9), tb_tunnel_reclaim_available_bandwidth(9) 💖💖💖

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that's the whole page bestie, hope you slayed 🫶✨ this one's from ./drivers/thunderbolt, dated October 2026, and the page you just read is tb_tunnel_alloc_dp(9) — mwah, bye! 💅🎀🦋