drm_crtc_vbl...vblank_timer(9)

💅 drm_crtc_vbl...vblank_timer(9)

okay so this is a page from the Kernel API Manual, and bestie, it's a whole little vibe about making a fake vblank out of a timer. yes it's as niche as it sounds and yes it's iconic. 🎀

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✨ NAME ✨

drm_crtc_vblank_helper_enable_vblank_timer — literally implements struct &drm_crtc_funcs.enable_vblank, that's the whole job 🫶

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🌸 SYNOPSIS 🌸

int drm_crtc_vblank_helper_enable_vblank_timer (struct drm_crtc *crtc );

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🦋 ARGUMENTS 🦋

• crtc — The CRTC. that's it, that's the argument, she's the main character 💅

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💖 DESCRIPTION 💖

okay so picture this: the helper drm_crtc_vblank_helper_enable_vblank_timer implements enable_vblank of struct drm_crtc_helper_funcs, but specifically for CRTCs that require a VBLANK timer — like, no hardware vblank to be found, so we're doing it ourselves, no cap ⭐

the way it works: it sets up the timer on the first invocation. once started, that timer expires after the current frame duration — and if you wanna know what that number actually is, go look at struct drm_vblank_crtc.framedur_ns, she's holding the receipts 💀

also see struct drm_crtc_helper_funcs.enable_vblank — same vibe, that's the callback we're filling in 🌈

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🔥 RETURN 🔥

0 on success, or a negative errno code otherwise 😭 (that's the "something went sideways" branch, we don't love her but she exists)

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👑 SEE ALSO 👑

• kernel file ./drivers/gpu/drm/drm_vblank_helper.c
• overview(9)
• drm_crtc_vblank_atomic_flush(9)
• drm_crtc_vblank_atomic_enable(9)
• drm_crtc_vblank_atomic_disable(9)
• drm_crtc_vblank_helper_disable_vblank_timer(9)
• drm_crtc_vblank_helper_get_vblank_timestamp_from_timer(9)

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that's the whole page bestie, go forth and timer your vblanks 🧚✨

cheers from ./drivers/gpu/drm — October 2026, page `drm_crtc_vbl...vblank_timer(9)**, mwah 💋