input_mt_assign_slots(9)

📦 version 7.3.1, in nixpkgs unstable

✨ input_mt_assign_slots(9) ✨

okay so bestie, welcome to the Kernel API Manual 💖 this one's a <9>-section page, aka kernel-internals territory, aka the part of town where the multitouch magic happens 🫶 we're talking input_mt_assign_slots today and honestly? she's the matchmaker of the input subsystem 💅

🌸 NAME 🌸

input_mt_assign_slots — perform a best-match assignment ✨

like, she looks at your contacts and your slots and goes "okay you two, you're a couple now" 🎀 no cap.

🦋 SYNOPSIS 🦋

int input_mt_assign_slots (struct input_dev *dev , int *slots , const
       struct input_mt_pos *pos , int num_pos , int dmax );

yes the line break is real, that's just how the manpage renders it, don't come for her 😭 copy it exactly, fr fr.

💜 ARGUMENTS 💜

  • dev — the input device that already has its MT slots allocated ✨. if you haven't allocated slots yet, bestie, go do that first, this function is not gonna do it for you 🙈
  • slots — the slot assignment array that's gonna get filled in 🫶 this is the output, the finished product, the glow-up 💅
  • pos — the position array you want to match against 🌸 these are the vibes we're trying to place
  • num_pos — how many positions are in that array, i.e. the headcount 👑
  • dmax — the maximum ABS_MT_POSITION displacement allowed, and heads up: zero means infinite ⭐ so don't be passing 0 thinking it means "no movement allowed", it's literally the opposite, iykyk 💀

🔥 DESCRIPTION 🔥

so what she does is: she runs a best match against the current contacts and hands you back the slot assignment list 📋✨. New contacts get assigned to unused slots — the way that a group chat adds a new member to the empty seat, very main character energy 👑

the assignments are balanced so that every single coordinate displacement stays below the euclidian distance dmax 🎀 that's the whole vibe check of the function. BUT — and this is important bestie — if no such assignment can be found, some contacts get assigned to unused slots anyway 🙈 she does her best, she doesn't just give up.

returns zero on success 🥳 or a negative error in case of failure 😭 that's it, that's the contract.

🧚 SEE ALSO 🧚

the kernel file lives at ./drivers/input/input-mt.c — go read it, she's iconic 📖💖 and then check out her whole friend group:

💖 ok that's the whole page bestie, you've got this. match those slots, respect the dmax, and remember: 0 means infinite, not zero 🫶✨

huge slay to the kernel devs over at ./drivers/input — this one's dated October 2026 and it's input_mt_assign_slots(9) forever and always 🎀💜

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