drm_crtc_helper_set_config(9)

💅 drm_crtc_helper_set_config(9) 💅

okay so this is the Kernel API Manual page for drm_crtc_helper_set_config(9), and bestie, we are getting into legacy CRTC helper business ✨

🌸 NAME 🌸

drm_crtc_helper_set_config — set a new config from userspace

✨ SYNOPSIS ✨

int drm_crtc_helper_set_config (struct drm_mode_set *set , struct
       drm_modeset_acquire_ctx *ctx );

🌀 ARGUMENTS 🌀

• set — mode set configuration
• ctx — lock acquire context, not used here — literally just vibing in the parameter list 🫶

💖 DESCRIPTION 💖

okay so drm_crtc_helper_set_config is the helper function that implements the drm_crtc_funcs.set_config callback for drivers using the legacy CRTC helpers. It's giving legacy-era main character energy, iykyk 💅

First thing it does: it tries to locate the best encoder for each connector by calling the connector drm_connector_helper_funcs.best_encoder helper operation. Bestie matching service, but for encoders ✨

After locating the appropriate encoders, the helper function calls the mode_fixup encoder and CRTC helper operations to adjust the requested mode — or reject it completely. If it rejects it, an error gets returned to the application. Rude, but valid 💀

If the new configuration after mode adjustment is identical to the current configuration, the helper function returns without performing any other operation. Literally “same vibe, bye” 🦋

If the adjusted mode is identical to the current mode but changes to the frame buffer need to be applied, drm_crtc_helper_set_config calls the CRTC drm_crtc_helper_funcs.mode_set_base helper operation. So: same mode, but frame buffer updates? It hits mode_set_base 🎀

If the adjusted mode differs from the current mode, or if the ->mode_set_base helper operation is not provided, the helper function performs a full mode set sequence by calling the ->prepare, ->mode_set and ->commit CRTC and encoder helper operations, in that order. Order matters, bestie — do not shuffle it 🙈 Alternatively it can also use the dpms and disable helper operations. For details see struct drm_crtc_helper_funcs and struct drm_encoder_helper_funcs 👑

⚠️ deprecated alert — this function is deprecated. New drivers must implement atomic modeset support, for which this function is unsuitable. Instead, drivers should use drm_atomic_helper_set_config. That's not a maybe, that's the official move, periodt 💅

🎀 RETURN 🎀

Returns 0 on success, negative errno numbers on failure. Clean, simple, iconic ✨

👑 SEE ALSO 👑

• Kernel file ./drivers/gpu/drm/drm_crtc_helper.c overview(9)
• drm_helper_encoder_in_use(9)
• drm_helper_crtc_in_use(9)
• drm_helper_disable_unused_functions(9)
• drm_crtc_helper_set_mode(9)
• drm_crtc_helper_atomic_check(9)
• drm_helper_connector_dpms(9)
• drm_helper_resume_force_mode(9)
• drm_helper_force_disable_all(9)

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byeee bestie 🫶 this page's source/version is ./drivers/gpu/drm, dated October 2026, and it's the drm_crtc_helper_set_config(9) page. Now go forth and set that config — or better yet, use atomic helpers 😭💖