drm_crtc_vblank_restore(9)

💅 drm_crtc_vblank_restore(9) — Kernel API Manual, bestie ✨

Okay so real talk, we're in the Kernel API Manual today and the star of the show is drm_crtc_vblank_restore(9). Yes the page header literally says drm_crtc_vblank_restore(9) twice, we love a self-referential queen. 🎀

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✨ NAME ✨

drm_crtc_vblank_restore — literally just estimate the vblanks you missed and update the vblank count. That's it. That's the whole vibe. 🦋

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🌸 SYNOPSIS 🌸

void drm_crtc_vblank_restore (struct drm_crtc *crtc );

No return value, it just does the thing. Periodt. 💅

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💖 ARGUMENTS 💖

• crtc — the CRTC in question. Like, the CRTC. The one we're talking about. 👑

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🧚 DESCRIPTION 🧚

So here's the tea: power management features can cause the frame counter to reset between vblank disable and enable. Rude, honestly. 😭

Drivers can use this function inside their drm_crtc_funcs.enable_vblank implementation to estimate how many vblanks got missed since the last drm_crtc_funcs.disable_vblank, using timestamps, and then update the vblank counter. Iconic recovery arc fr fr. ✨

⚠️ Okay this part matters so listen up 👀 — drivers must have race-free high-precision timestamping support. That means drm_crtc_funcs.get_vblank_timestamp has to be hooked up, and drm_vblank_crtc_config.disable_immediate must be set, to indicate that the time-stamping functions are race-free against vblank hardware counter increments. No cap, if that's not set up you're gonna have a bad time. 💀

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🔥 SEE ALSO 🔥

Everything is connected, bestie, this is the whole friend group 🫶:

• Kernel file ./drivers/gpu/drm/drm_vblank.c vblank handling(9)
• drm_crtc_accurate_vblank_count(9)
• drm_vblank_init(9)
• drm_dev_has_vblank(9)
• drm_crtc_vblank_waitqueue(9)
• drm_calc_timestamping_constants(9)
• drm_crtc_vblank_helper_get_vblank_timestamp_internal(9)
• drm_crtc_vblank_helper_get_vblank_timestamp(9)
• drm_crtc_get_last_vbltimestamp(9)
• drm_crtc_vblank_count(9)
• drm_vblank_count_and_time(9)
• drm_crtc_vblank_count_and_time(9)
• drm_crtc_next_vblank_start(9)
• drm_crtc_arm_vblank_event(9)
• drm_crtc_send_vblank_event(9)
• drm_crtc_vblank_get(9)
• drm_crtc_vblank_put(9)
• drm_crtc_wait_one_vblank(9)
• drm_crtc_vblank_off(9)
• drm_crtc_vblank_reset(9)
• drm_crtc_set_max_vblank_count(9)
• drm_crtc_vblank_on_config(9)
• drm_crtc_vblank_on(9)
• drm_handle_vblank(9)
• drm_crtc_handle_vblank(9)
• drm_crtc_vblank_start_timer(9)
• drm_crtc_vblank_cancel_timer(9)
• drm_crtc_vblank_get_vblank_timeout(9)

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Okay that's the whole page, mwah 💋 — brought to you by the source at ./drivers/gpu/drm, version October 2026, and yeah the footer really does say drm_crtc_vblank_restore(9) again because the branding is consistent and we respect it. Stay timestamped, stay race-free, ily! 🌈💜