media_device...ister_entity(9)

💖 media_device_register_entity(9) — the Kernel API Manual, but make it a group chat 🎀

okay so bestie, this one's from the Kernel API Manual and it's literally a whole page about getting a media entity registered. sit down, hydrate, let's go ✨

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🌸 NAME 🌸

media_device_register_entity — ngl the entire job is: it registers a media entity inside a media device that was already registered earlier. that's it. that's the vibe 💅

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🦋 SYNOPSIS 🦋

int media_device_register_entity (struct media_device *mdev , struct media_entity *entity );

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✨ ARGUMENTS ✨

• mdev — a pointer to struct media_device, aka the media device doing the hosting 👑
• entity — a pointer to the struct media_entity that you want registered 🫶

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💜 DESCRIPTION 💜

so entities get identified by a unique positive integer ID, right? and the media controller framework will hand out that ID for you automatically — you don't gotta do a thing 🌈

but hear me out: those IDs are not guaranteed to be contiguous, and the ID number can change on newer Kernel versions 😭 so like… neither the driver nor userspace should hardcode ID numbers to refer to entities. do not do it. instead, use the framework to find the ID whenever you actually need it. that's the whole move, periodt 💀

the media_entity name, type and flags fields should all be initialized before you call media_device_register_entity. and if the entities are embedded in higher-level standard structures, some of those fields can already be set by the higher-level framework — so lowkey check before you go overwriting stuff 🙈

if the device has pads, media_entity_pads_init should be called before this function. if it doesn't have pads, then media_entity.pad and media_entity.num_pads should be zeroed out before you call this. either way, handle it first, bestie 🎀

entities have flags that describe the entity's capabilities and state:

• MEDIA_ENT_FL_DEFAULT — indicates the default entity for a given type. you can use this to report the default audio and video devices, or the default camera sensor 📸

📝 NOTE 📝

Drivers should set the entity function before calling this function. and pleaseeee notice that the values MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN and MEDIA_ENT_F_UNKNOWN should not be used by the drivers. like, don't. for real fr fr 🚫

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🔥 SEE ALSO 🔥

• Kernel file ./include/media/media-device.h 📁
• struct media_entity_notify(9)
• struct media_device_ops(9)
• struct media_device(9)
• media_device_init(9)
• media_device_cleanup(9)
• __media_device_register(9)
• media_device_register(9)
• media_device_unregister(9)
• media_device_unregister_entity(9)
• media_device_register_entity_notify(9)
• media_device_unregister_entity_notify(9)
• media_device_pci_init(9)
• __media_device_usb_init(9)
• media_device_usb_init(9)
• media_set_bus_info(9)

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and that's the page, icon ✨ this lil' corner lives in ./include/media, stamped October 2026, and the whole thing goes by media_device...ister_entity(9) — mwah, go register something responsibly 💅💖🧚