__set_legacy_tf(9)

💅 __set_legacy_tf(9) — the Kernel API Manual, bestie edition 🎀

okay so you're in section 9 of the Kernel API Manual and the function we're absolutely obsessing over today is called __set_legacy_tf — yes the double underscore is part of the name, it's giving "internal, don't touch unless you know her" 💅

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✨ NAME ✨

__set_legacy_tf — literally just calculates the legacy transfer function. that's it. that's the whole vibe check. 🦋

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🌸 SYNOPSIS 🌸

int __set_legacy_tf (struct dc_transfer_func *func , const struct
       drm_color_lut *lut , uint32_t lut_size , bool has_rom );

copy it exactly like that, no cap, the line break is canon 🫶

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🎀 ARGUMENTS 🎀

• func — the transfer function itself, the main character of this whole operation 👑
• lut — the lookup table that defines the color space. she's the blueprint. the blueprint is her. 🍓
• lut_size — the size of the respective lut, aka how many entries that particular table is serving ✨
• has_rom — a bool that says whether ROM can be used for the hardcoded curve. like, is the built-in backup allowed to show up? 💀

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💖 DESCRIPTION 💖

Only for sRGB input space.

that's the entire description and honestly? iconic. short. mysterious. does not elaborate. 🙈

real talk though — don't just yeet this at any old color space, it's specifically for sRGB input space and that's the rule 🌈

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⭐ RETURN ⭐

• 0 — in case of success 🎉
• -ENOMEM — if it fails 😭 (memory said no)

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🦋 SEE ALSO 🦋

Kernel file ./drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_color.c

and the whole friend group:

• overview(9)
• amdgpu_dm_init_color_mod(9)
• __extract_blob_lut(9)
• __extract_blob_lut32(9)
• __is_lut_linear(9)
• __drm_lut_to_dc_gamma(9)
• __drm_lut32_to_dc_gamma(9)
• __drm_ctm_to_dc_matrix(9)
• __drm_ctm_3x4_to_dc_matrix(9)
• __set_output_tf(9)
• __set_output_tf_32(9)
• __set_input_tf(9)
• __set_input_tf_32(9)
• amdgpu_dm_verify_lut3d_size(9)
• amdgpu_dm_verify_lut_sizes(9)
• amdgpu_dm_check_crtc_color_mgmt(9)
• amdgpu_dm_update_crtc_color_mgmt(9)
• amdgpu_dm_update_plane_color_mgmt(9)

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and that's the page, bestie!! 💜 this one comes to you from ./drivers/gpu/drm/amd/display/... and it's dated October 2026 — mark your calendars, the legacy transfer function is not going anywhere 🗓️✨ periodt