drm_atomic_..._fake_vblank(9)

✨ drm_atomic_..._fake_vblank(9) ✨

okay bestie so you've wandered into the Kernel API Manual 💖 — this is the page for drm_atomic_..._fake_vblank(9) and honestly it's a little niche but it's giving "unsung hero of the display pipeline" energy, so let's get into it 🫶

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🌸 NAME 🌸

drm_atomic_helper_fake_vblank — fake VBLANK events if needed 💅

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🎀 SYNOPSIS 🎀

void drm_atomic_helper_fake_vblank (struct drm_atomic_commit *state );

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🦋 ARGUMENTS 🦋

• state — the atomic state object being committed ✨ like, this is the thing you're pushing through, bestie.

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👑 DESCRIPTION 👑

so here's the tea ☕: this function walks all the CRTCs and fakes VBLANK events on the ones where drm_crtc_state.no_vblank is set to true and drm_crtc_state.event != NULL. Both conditions, no shortcuts, periodt 💅

The primary use of this function is writeback connectors working in oneshot mode and faking VBLANK events. In that case, they only fake the VBLANK event when a job is queued 🔥 and — this is the important bit — any change to the pipeline that does not touch the connector is leading to timeouts when calling drm_atomic_helper_wait_for_vblanks or drm_atomic_helper_wait_for_flip_done 😭 like, the wait just sits there, main character waiting forever, nobody's coming.

In addition to writeback connectors, this function can also fake VBLANK events for CRTCs without VBLANK interrupt ✨ (yes, those exist, and yes, they also deserve love).

ngl this whole thing is part of the atomic helper support for nonblocking commits — go peek at drm_atomic_helper_setup_commit for the overview, iykyk 🧚

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💜 SEE ALSO 💜

okay this list is long but every single one is here, don't come for me 💀

• Kernel file ./drivers/gpu/drm/drm_atomic_helper.c, overview(9)
• drm_atomic_helper_check_modeset(9)
• drm_atomic_helper_check_wb_connector_state(9)
• drm_atomic_helper_check_plane_state(9)
• drm_atomic_helper_check_crtc_primary_plane(9)
• drm_atomic_helper_check_planes(9)
• drm_atomic_helper_check(9)
• drm_atomic_helper_commit_encoder_bridge_disable(9)
• drm_atomic_helper_commit_crtc_disable(9)
• drm_atomic_helper_commit_encoder_bridge_post_disable(9)
• drm_atomic_helper_update_legacy_modeset_state(9)
• drm_atomic_helper_calc_timestamping_constants(9)
• drm_atomic_helper_commit_crtc_set_mode(9)
• drm_atomic_helper_commit_modeset_disables(9)
• drm_atomic_helper_commit_writebacks(9)
• drm_atomic_helper_commit_encoder_bridge_pre_enable(9)
• drm_atomic_helper_commit_crtc_enable(9)
• drm_atomic_helper_commit_encoder_bridge_enable(9)
• drm_atomic_helper_commit_modeset_enables(9)
• drm_atomic_helper_wait_for_fences(9)
• drm_atomic_helper_wait_for_vblanks(9)
• drm_atomic_helper_wait_for_flip_done(9)
• drm_atomic_helper_commit_tail(9)
• drm_atomic_helper_commit_tail_rpm(9)
• drm_atomic_helper_async_check(9)
• drm_atomic_helper_async_commit(9)
• drm_atomic_helper_commit(9)
• implementing nonblocking commit(9)
• drm_atomic_helper_setup_commit(9)
• drm_atomic_helper_wait_for_dependencies(9)
• drm_atomic_helper_commit_hw_done(9)
• drm_atomic_helper_commit_cleanup_done(9)
• drm_atomic_helper_prepare_planes(9)
• drm_atomic_helper_unprepare_planes(9)
• drm_atomic_helper_commit_planes(9)
• drm_atomic_helper_commit_planes_on_crtc(9)
• drm_atomic_helper_disable_planes_on_crtc(9)
• drm_atomic_helper_cleanup_planes(9)
• drm_atomic_helper_swap_state(9)
• drm_atomic_helper_update_plane(9)
• drm_atomic_helper_disable_plane(9)
• drm_atomic_helper_set_config(9)
• drm_atomic_helper_disable_all(9)
• drm_atomic_helper_reset_crtc(9)
• drm_atomic_helper_shutdown(9)
• drm_atomic_helper_duplicate_state(9)
• drm_atomic_helper_suspend(9)
• drm_atomic_helper_commit_duplicated_state(9)
• drm_atomic_helper_resume(9)
• drm_atomic_helper_page_flip(9)
• drm_atomic_helper_page_flip_target(9)
• drm_atomic_helper_bridge_propagate_bus_fmt(9)
• drm_atomic_helper_bridge_get_hdmi_output_bus_fmts(9)

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and that's the whole page bestie, you ate that reading it 🌈✨

sign-off vibes: this one lives in ./drivers/gpu/drm, dated October 2026, and its whole identity is drm_atomic_..._fake_vblank(9) — slay 💅🎀🦋