drm_crtc_vblank_count(9)

💖 drm_crtc_vblank_count(9) 💖

okay so bestie, we are in the Kernel API Manual and today's main character is drm_crtc_vblank_count(9). it's a tiny little vblank counter getter and it has lore. ✨

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🎀 NAME 🎀

drm_crtc_vblank_count — retrieve the "cooked" vblank counter value. 🍓

🌸 SYNOPSIS 🌸

u64 drm_crtc_vblank_count (struct drm_crtc *crtc );

🦋 ARGUMENTS 🦋

• crtc — which counter to retrieve. yes, which one. choose ur fighter. 💅

✨ DESCRIPTION ✨

this function fetches the "cooked" vblank count value. that value represents the number of vblank events since the system was booted, including lost events due to modesetting activity. 👑

note: this timer isn't correct against a racing vblank interrupt (since it only reports the software vblank counter). see drm_crtc_accurate_vblank_count for such use-cases. 😭

Also, for a given vblank counter value, drm_crtc_handle_vblank and drm_crtc_vblank_count or drm_crtc_vblank_count_and_time provide a barrier: any writes done before calling drm_crtc_handle_vblank will be visible to callers of the later functions, if the vblank count is the same or a later one. 🫶

see also drm_vblank_crtc.count. 👀

🔥 RETURN 🔥

the software vblank counter. periodt. 💖

🌈 SEE ALSO 🌈

okay bestie, the vblank cinematic universe is huge, here's 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_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_crtc_vblank_restore(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)

mwah 💋 that's the whole page. it's from the Kernel API Manual, source ./drivers/gpu/drm, dated October 2026, and yes the title is drm_crtc_vblank_count(9). love u, go count some vblanks responsibly! 🫶✨