STRUCT AMDGPU_DM_BACKLIGHT_CAPS(9)

🌸 NAME 🌸

struct amdgpu_dm_backlight_caps — literally all the info about backlight, bestie ✨

Okay so we're in the Kernel API Manual today (struct amdg...cklight_caps(9), iykyk) and this struct is the main character. It holds everything about how your display does brightness. Let's get into it 💅

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🦋 SYNOPSIS 🦋

struct amdgpu_dm_backlight_caps {
    union dpcd_sink_ext_caps *ext_caps;
    u32 aux_min_input_signal;
    u32 aux_max_input_signal;
    int min_input_signal;
    int max_input_signal;
    bool caps_valid;
    bool aux_support;
    u32 brightness_mask;
    u8 ac_level;
    u8 dc_level;
    u8 data_points;
    struct amdgpu_dm_luminance_data luminance_data[MAX_LUMINANCE_DATA_POINTS];
};

No cap, that's the whole shape of it 🫶

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🎀 Members 🎀

Okay, member-by-member, let's go — every single one, because we do not skip 💖

• ext_caps — keeps the data struct that has all the info about the display's support for HDR ✨
• aux_min_input_signal — the min brightness value supported by the display
• aux_max_input_signal — the max brightness value supported by the display, in nits 🔥
• min_input_signal — the minimum possible input, in the range 0-255
• max_input_signal — the maximum possible input, in the range 0-255
• caps_valid — true if these values came from the ACPI interface 👑
• aux_support — tells you whether the display supports AUX backlight
• brightness_mask — after deriving brightness, OR it with this mask. It's a workaround for panels that have issues with certain brightness values, so yeah, it's doing the lord's work 🙈
• ac_level — the default brightness if you booted on AC ⚡
• dc_level — the default brightness if you booted on DC 🔋
• data_points — the number of custom luminance data points
• luminance_data — the custom luminance data itself 💜

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🌈 Description 🌈

It describes the backlight support for ACPI or eDP AUX. That's the whole vibe check, fr fr.

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⭐ SEE ALSO ⭐

Kernel file ./drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.h, plus these iconic structs you should also go read:

• struct dm_compressor_info(9)
• struct dm_boot_time_crc_info(9)
• struct dmub_hpd_work(9)
• struct vblank_control_work(9)
• struct idle_workqueue(9)
• struct vupdate_offload_work(9)
• struct amdgpu_dm_luminance_data(9)
• struct dal_allocation(9)
• struct hpd_rx_irq_offload_work_queue(9)
• struct hpd_rx_irq_offload_work(9)
• struct amdgpu_display_manager(9)
• struct amdgpu_hdmi_vsdb_info(9)

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Bestie moment: all of these live over in ./drivers/gpu/drm/amd/display/... if you wanna go snooping 💀

And that's the page! Brought to you by the gang over in ./drivers/gpu/drm/amd/display/..., dated October 2026 — go off, calendar 📅💖 Slay, and see you in the next struct 🧚‍♀️✨🎀