drm_cvt_mode(9)

✨ drm_cvt_mode(9) ✨

okay so bestie, welcome to the Kernel API Manual 💅 this one's a kernel page, and we're talking about drm_cvt_mode — the lil function that builds you a modeline using the CVT algorithm. iconic behavior tbh 🎀

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🌸 NAME 🌸

drm_cvt_mode — create a modeline based on the CVT algorithm ✨

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🦋 SYNOPSIS 🦋

struct drm_display_mode * drm_cvt_mode (struct drm_device *dev , int
hdisplay , int vdisplay , int vrefresh , bool reduced , bool interlaced
, bool margins );

like, it takes a whole lil friend group of args and hands you back a struct drm_display_mode * 🫶

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💖 ARGUMENTS 💖

• dev — drm device 💻 (the main character, obviously)
• hdisplay — hdisplay size 📐
• vdisplay — vdisplay size 📏
• vrefresh — vrefresh rate 🔄
• reduced — whether to use reduced blanking 🫧
• interlaced — whether to compute an interlaced mode 🌀
• margins — whether to add margins (borders) 🖼️

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👑 DESCRIPTION 👑

so this function is the one you call when you want to generate the modeline based on the CVT algorithm, using your hdisplay, vdisplay, and vrefresh values 💫 ngl it's giving math girlie and we love that for her.

the lore?? it's based from the VESA(TM) Coordinated Video Timing Generator by Graham Loveridge, dated April 9, 2003, and you can find that at http://www.elo.utfsm.cl/~elo212/docs/CVTd6r1.xls 📊 (yes bestie, an .xls file, we stan a spreadsheet era 💀).

and it's also copied from xf86CVTmode in xserver/hw/xfree86/modes/xf86cvt.c. what the author did — and I'm quoting the vibe here — is translate it by using integer calculation 🧮✨ no floats, no drama, just integers slaying.

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🎀 RETURN 🎀

you get the modeline based on the CVT algorithm, stored in a drm_display_mode object 😌💖 and that display mode object is allocated with drm_mode_create.

heads up bestie 🚨 it returns NULL when no mode could be allocated — so like, always check, fr fr 🙈

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🌈 SEE ALSO 🌈

• Kernel file ./drivers/gpu/drm/drm_modes.c 🗂️

and the whole extended fam 👇

• drm_mode_debug_printmodeline(9)
• drm_mode_create(9)
• drm_mode_destroy(9)
• drm_mode_probed_add(9)
• drm_analog_tv_mode(9)
• drm_gtf_mode_complex(9)
• drm_gtf_mode(9)
• drm_display_mode_from_videomode(9)
• drm_display_mode_to_videomode(9)
• drm_bus_flags_from_videomode(9)
• of_get_drm_display_mode(9)
• of_get_drm_panel_display_mode(9)
• drm_mode_set_name(9)
• drm_mode_vrefresh(9)
• drm_mode_get_hv_timing(9)
• drm_mode_set_crtcinfo(9)
• drm_mode_copy(9)
• drm_mode_init(9)
• drm_mode_duplicate(9)
• drm_mode_match(9)
• drm_mode_equal(9)
• drm_mode_equal_no_clocks(9)
• drm_mode_equal_no_clocks_no_stereo(9)
• drm_mode_validate_driver(9)
• drm_mode_validate_size(9)
• drm_mode_validate_ycbcr420(9)
• drm_mode_prune_invalid(9)
• drm_mode_compare(9)
• drm_mode_sort(9)
• drm_connector_list_update(9)
• drm_mode_parse_command_line_for_connector(9)
• drm_mode_create_from_cmdline_mode(9)
• drm_mode_convert_to_umode(9)
• drm_mode_convert_umode(9)
• drm_mode_is_420_only(9)
• drm_mode_is_420_also(9)
• drm_mode_is_420(9)
• drm_set_preferred_mode(9)

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and that's the whole page bestie!! 💜 this one lives in ./drivers/gpu/drm and the version/date stamp is October 2026 — so like, future-era manual page energy 🦋✨ mwah, go forth and compute those modelines 💅🎀