v4l2_subdev_call(9)

💅 v4l2_subdev_call — the kAPI manual, bestie edition 🎀

okay so welcome to the Kernel API Manual entry for v4l2_subdev_call(9), aka the little macro wrapper that makes your media driver actually do things ✨ grab a matcha, this one's short and sweet fr fr.

---

🌸 NAME 🌸

v4l2_subdev_call — call an operation of a v4l2_subdev. that's it. that's the whole vibe 💖

---

🦋 SYNOPSIS 🦋

v4l2_subdev_call (sd , o , f , args... );

lowkey the prettiest signature ever, no cap 🫶

---

✨ ARGUMENTS ✨

• sd — pointer to the struct v4l2_subdev 👑 like, the subdev you're trying to talk to. this is your main character.
• o — the name of the element at struct v4l2_subdev_ops that contains f. each element there groups a set of callback functions, so think of it as picking which drawer in the ops dresser you're opening 🗄️
• f — the callback function to be called. the callback functions are defined in groups, according to each element at struct v4l2_subdev_ops — so o picks the group, f picks the function inside it 💅
• args — arguments for f. whatever that callback wants, you hand it over 🎁

---

🌈 EXAMPLE 🌈

err = v4l2_subdev_call(sd, video, s_std, norm);

see how it reads?? sd = the subdev, video = the ops group, s_std = the callback, norm = the arg. literally iconic. ate and left no crumbs 🔥

---

⭐ SEE ALSO ⭐

first up, the header home base, bestie:

• Kernel file ./include/media/v4l2-subdev.h struct

and then the whole entire friend group 😭 like genuinely the longest guest list at the function:

• v4l2_decode_vbi_line(9)
• enum v4l2_subdev_io_pin_bits(9)
• struct v4l2_subdev_io_pin_config(9)
• struct v4l2_subdev_core_ops(9)
• struct v4l2_subdev_tuner_ops(9)
• struct v4l2_subdev_audio_ops(9)
• struct v4l2_mbus_frame_desc_entry_csi2(9)
• enum v4l2_mbus_frame_desc_flags(9)
• struct v4l2_mbus_frame_desc_entry(9)
• enum v4l2_mbus_frame_desc_type(9)
• struct v4l2_mbus_frame_desc(9)
• enum v4l2_subdev_pre_streamon_flags(9)
• struct v4l2_subdev_video_ops(9)
• struct v4l2_subdev_vbi_ops(9)
• struct v4l2_subdev_sensor_ops(9)
• enum v4l2_subdev_ir_mode(9)
• struct v4l2_subdev_ir_parameters(9)
• struct v4l2_subdev_ir_ops(9)
• struct v4l2_subdev_pad_config(9)
• struct v4l2_subdev_stream_configs(9)
• struct v4l2_subdev_krouting(9)
• struct v4l2_subdev_state(9)
• struct v4l2_subdev_pad_ops(9)
• struct v4l2_subdev_ops(9)
• struct v4l2_subdev_internal_ops(9)
• struct v4l2_subdev_platform_data(9)
• struct v4l2_subdev(9)
• media_entity_to_v4l2_subdev(9)
• vdev_to_v4l2_subdev(9)
• struct v4l2_subdev_fh(9)
• to_v4l2_subdev_fh(9)
• v4l2_set_subdevdata(9)
• v4l2_get_subdevdata(9)
• v4l2_set_subdev_hostdata(9)
• v4l2_get_subdev_hostdata(9)
• v4l2_subdev_get_fwnode_pad_1_to_1(9)
• v4l2_subdev_link_validate_default(9)
• v4l2_subdev_link_validate(9)
• v4l2_subdev_has_pad_interdep(9)
• __v4l2_subdev_state_alloc(9)
• __v4l2_subdev_state_free(9)
• v4l2_subdev_init_finalize(9)
• v4l2_subdev_cleanup(9)
• v4l2_subdev_state_get_format(9)
• v4l2_subdev_state_get_crop(9)
• v4l2_subdev_state_get_compose(9)
• v4l2_subdev_state_get_interval(9)
• v4l2_subdev_get_fmt(9)
• v4l2_subdev_get_frame_interval(9)
• v4l2_subdev_set_routing(9)
• for_each_active_route(9)
• v4l2_subdev_set_routing_with_fmt(9)
• v4l2_subdev_routing_find_opposite_end(9)
• v4l2_subdev_state_get_opposite_stream_format(9)
• v4l2_subdev_state_xlate_streams(9)
• enum v4l2_subdev_routing_restriction(9)
• v4l2_subdev_routing_validate(9)
• v4l2_subdev_enable_streams(9)
• v4l2_subdev_disable_streams(9)
• v4l2_subdev_s_stream_helper(9)
• __v4l2_subdev_get_frame_desc_passthrough(9)
• v4l2_subdev_get_frame_desc_passthrough(9)
• v4l2_subdev_lock_state(9)
• v4l2_subdev_unlock_state(9)
• v4l2_subdev_lock_states(9)
• v4l2_subdev_unlock_states(9)
• v4l2_subdev_get_unlocked_active_state(9)
• v4l2_subdev_get_locked_active_state(9)
• v4l2_subdev_lock_and_get_active_state(9)
• v4l2_subdev_init(9)
• v4l2_subdev_call_state_active(9)
• v4l2_subdev_call_state_try(9)
• v4l2_subdev_has_op(9)
• v4l2_subdev_notify_event(9)
• v4l2_subdev_is_streaming(9)

---

bestie REMEMBER: the vibe check here is that o is an element name of struct v4l2_subdev_ops, and f lives inside that element. don't mix 'em up or it's giving undefined silliness 💀

---

and that's the whole page, mwah 💋 this gem dropped from ./include/media, dated October 2026, and it's filed under v4l2_subdev_call(9) — go forth and call your subdev, queen 👑🦋💜