v4l2_subdev_...get_interval(9)

🌸 v4l2_subdev_state_get_interval — like, the whole vibe 💅

Ok so bestie, real talk: this is a page from the Kernel API Manual, and the function on the cover is v4l2_subdev_...get_interval(9). Yes the title is truncated, no I don't know why, the man page people just did that. The full name is v4l2_subdev_state_get_interval and it's actually so simple. Let's go. ✨

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✨ NAME ✨

v4l2_subdev_state_get_interval — get a pointer to a stream frame interval. That's it, that's the whole job. 🎀

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✨ SYNOPSIS ✨

v4l2_subdev_state_get_interval (state , pad , ... );

Look at her. Three args, one of them is literally .... Main character energy tbh. 👑

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✨ ARGUMENTS ✨

• state — the subdevice state. The whole mood board. 🪩
• pad — the pad id. Which pad we're talking about, bestie. 📍
• ... — the stream id, and psst, it's an optional argument. Optional, like your situationship. 🙈

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✨ DESCRIPTION ✨

So what does it do? It returns a pointer to the frame interval for the given pad + stream, inside the subdev state. Pointer. Not a copy. Not a vibe. A pointer. 🫶

And here's the little plot twist: for stream-unaware drivers, you get the frame interval for the corresponding pad instead. Makes sense, they don't do streams, so the pad is the whole story. 💫

And if the pad doesn't exist? NULL is returned. Nothing. Nada. The void. 😭 Don't dereference it, I'm begging.

Real talk: the return is a pointer, so check it before you touch it. If the pad doesn't exist you get NULL and that's the documented behavior, not a bug. 🫡

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✨ SEE ALSO ✨

Kernel file ./include/media/v4l2-subdev.h — go read it, it's lowkey iconic. 🌈 And here's the entire friend group, no cap, every single one:

• struct 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_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(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)

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Ok that's the whole thing, you ate that. 🍓

Later, bestie — this one lives in ./include/media, it's from the Kernel API Manual, dated October 2026. Go touch some pads (the v4l2 kind). 💜🦋