STRUCT BACKLIGHT_DEVICE(9)

💅 struct backlight_device(9) — the backlight device data page, bestie ✨

okay so real quick: this is a page from the Kernel API Manual, and it's all about struct backlight_device — the data blob that is a backlight device in the kernel. let's get into it 🫶

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✨ NAME ✨

struct backlight_device — backlight device data, literally the whole point of this page 💖

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🌸 SYNOPSIS 🌸

struct backlight_device {
    struct backlight_properties props;
    struct mutex update_lock;
    struct mutex ops_lock;
    const struct backlight_ops *ops;
    struct list_head entry;
    struct device dev;
    int use_count;
 };

like, that's the shape of it. now let's meet the members one by one 👑

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🎀 Members 🎀

• props — Backlight properties. that's it, that's the vibe ✨
• update_lock — The lock used when calling the update_status operation.

update_lock is an internal backlight lock that serialise access to the update_status operation. The backlight core holds the update_lock when calling the update_status operation. and here's the important bit, no cap: the update_lock shall not be used by backlight drivers 🙅‍♀️

• update_lock — (yep, listed a second time in the source page 💀 the note below is still all about update_lock.)

update_lock is an internal backlight lock that serialise access to the update_status operation. The backlight core holds the update_lock when calling the update_status operation. The update_lock shall not be used by backlight drivers 🫶

• ops_lock — The lock used around everything related to backlight_ops.

ops_lock is an internal backlight lock that protects the ops pointer and is used around all accesses to ops and when the operations are invoked. and same energy as above: the ops_lock shall not be used by backlight drivers ⚠️

• ops — Pointer to the backlight operations.

If ops is NULL, the driver that registered this device has been unloaded, and if class_get_devdata points to something in the body of that driver, it is also invalid. so yeah, NULL here is giving "everything's gone, don't touch it" 💀

• entry — List entry of all registered backlight devices 🦋
• dev — Parent device. the main character's parent, iykyk 👑
• use_count — The number of unblanked displays. lowkey a little counter of how many screens are awake rn 🌈

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💜 Description 💜

This structure holds all data required by a backlight device. that's the whole summary — it's the everything-bagel of backlight data 🍓

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🔥 SEE ALSO 🔥

go look at these next, bestie, they're all in the kernel file ./include/linux/backlight.h:

• enum backlight_update_reason(9)
• enum backlight_type(9)
• struct backlight_ops(9)
• struct backlight_properties(9)
• backlight_update_status(9)
• backlight_enable(9)
• backlight_disable(9)
• backlight_is_blank(9)
• backlight_get_brightness(9)
• bl_get_data(9)

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reminder: update_lock and ops_lock are internal, so drivers stay out of them, periodt 💅

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and that's the page!! it lives in ./include/linux, dated October 2026, and it's filed under struct backlight_device(9) — slay, go read the header file now, ily bye 🧚💖