fb_get_vblank(9)

🎀 fb_get_vblank(9) 🎀

okay so we're in the Kernel API Manual, and this is the page for fb_get_vblank(9). it's giving very specific kernel math energy, and honestly? iconic. 💖

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✨ NAME ✨

fb_get_vblank — get vertical blank time. that's the whole name vibe, bestie. 💅

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🌸 SYNOPSIS 🌸

here's the signature, exactly as it is:

u32 fb_get_vblank (u32 hfreq );

literally copy it like that, spaces and all. no cap. ✨

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🎀 ARGUMENTS 🎀

• hfreq — horizontal freq. that's it. that's the argument. 🦋

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💅 DESCRIPTION 💅

okay so the main formula is literally this:

vblank = right_margin + vsync_len + left_margin

and the given numbers are right here:

given: right_margin = 1 (V_FRONTPORCH) vsync_len    = 3 flyback      =
550

then the left_margin math is giving this exact layout:

flyback * hfreq left_margin  = --------------- - vsync_len 1000000

that's the whole description, bestie. the math is mathing. 🫶

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🌈 SEE ALSO 🌈

go check these besties:

• Kernel file ./drivers/video/fbdev/core/fbmon.c
• fb_create_modedb(9)
• fb_destroy_modedb(9)
• fb_get_hblank_by_hfreq(9)
• fb_get_hblank_by_dclk(9)
• fb_get_hfreq(9)
• of_get_fb_videomode(9)

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💖 that's the page, bestie! source/version: ./drivers/video/fbdev/core · date: October 2026 · go get that vertical blank time 💅✨