v4l2_ctrl_add_handler(9)

📦 version 7.3.1, in nixpkgs unstable

💅 v4l2_ctrl_add_handler(9) — the Kernel API Manual, bestie edition 🎀

okay so this one is from the Kernel API Manual (yes, that's the manual page name, we're folding it in like a cute little bow 🎀) and it's all about v4l2_ctrl_add_handler — the function that scoops up a whole pile of controls from one handler and yeets them into another. honestly iconic behavior. ✨

✨ NAME ✨

v4l2_ctrl_add_handler — literally just: add all the controls from handler @add over to handler @hdl. that's the whole vibe. 🫶

🦋 SYNOPSIS 🦋

int v4l2_ctrl_add_handler (struct v4l2_ctrl_handler *hdl , struct
       v4l2_ctrl_handler *add , v4l2_ctrl_filter filter , bool from_other_dev
       );

like, four args, one int back. slay. 💅

🌸 ARGUMENTS 🌸

  • hdl — the control handler. the destination. the main character handler, if you will 👑
  • add — the control handler whose controls you want to add to the hdl control handler. it's the donor handler, giving its little controls away 💖
  • filter — this function will filter which controls should be added. it's the bouncer at the door of the control party 🚪
  • from_other_dev — if true, then the controls in add were defined in another device than hdl. so like, cross-device controls, we're being honest about it 🫶

💜 DESCRIPTION 💜

okay so here's the tea ☕:

Does nothing if either of the two handlers is a NULL pointer. that's it. no drama, no crash, just a polite little nothing. 🙈

If filter is NULL, then all controls are added. no filter, no problem, everyone's invited 🎉

Otherwise only those controls for which filter returns true will be added. the rest? not invited. sorry bestie 😭

and ngl, in case of an error hdl->error will be set to the error code (if it wasn't set already). so always peep that error field afterwards, fr fr 💀

⭐ SEE ALSO ⭐

the whole extended friend group 💖 — Kernel file ./include/media/v4l2-ctrls.h:

and that's the whole page bestie, no cap, every single detail intact 💯

ily, go read some more kernel docs 🧚✨ this little masterpiece lives in ./include/media and it's dated October 2026, brought to you by the lovely humans of the Kernel API Manual — and the page's own name is, of course, v4l2_ctrl_add_handler(9). mwah 💋 periodt. 🎀

📦 where this page comes from