vb2_queue_change_type(9)

📦 version 7.3.1, in nixpkgs unstable

💅 vb2_queue_change_type 💅

ok so this is a page from the Kernel API Manual, bestie — we're literally in kernel land today, and this function is lowkey iconic. 🎀

✨ NAME ✨

vb2_queue_change_type — changes the type of an inactive vb2_queue 🦋

Like, it swaps the vibe of the queue's type — but only when nothing's going on. Noted. 🔥

🌸 SYNOPSIS 🌸

int vb2_queue_change_type (struct vb2_queue *q , unsigned int type );

🎀 ARGUMENTS 🎀

  • q — pointer to struct vb2_queue with videobuf2 queue. this is the queue we're doing a little makeover on 💅
  • type — the type to change to (V4L2_BUF_TYPE_VIDEO_*). yes bestie, it must be one of those ✨

🦋 DESCRIPTION 🦋

okay so here's the tea ☕ — this function changes the type of the vb2_queue. but there's a catch, and the catch is giving "you can only do this when the queue is free": it's only possible if the queue is not busy (i.e. no buffers have been allocated). no buffers = green light, bestie. buffers = not today. 😭

the way that vb2_queue_change_type is used? it's for supporting multiple buffer types using the same queue — one queue, many looks, we love a versatile icon 👑

so like, the driver can implement the v4l2_ioctl_ops.vidioc_reqbufs and v4l2_ioctl_ops.vidioc_create_bufs functions and call vb2_queue_change_type before calling vb2_ioctl_reqbufs or vb2_ioctl_create_bufs — and boom, that "locks" the buffer type until the buffers have been released. 🔒 periodt. that's the whole strategy and honestly it ate. 🌈

ngl the ordering matters: change the type first, then call vb2_ioctl_reqbufs or vb2_ioctl_create_bufs. miss that and you're giving chaotic energy, not main character energy. 💀

💜 SEE ALSO 💜

all the besties this function hangs out with 🫶 — first up, the kernel file:

like, read them. or don't. but they're there. 💖

ok that's the whole page, you're so welcome 🧚 and before you go — this cutie lives in ./include/media, and the page is dated October 2026 ⭐ mwah, stan kernel docs, byeeeee 💅✨🍓

📦 where this page comes from