DISPLAY PLLS(9)

💅 Display PLLs(9) — a.k.a. the Display PLLs page from the Kernel API Manual ✨

okay so bestie, grab a 🍓 and settle in, because this one is all about Display PLLs — the literal main character clocks that drive your outputs 🎀

🌸 DESCRIPTION 🌸

so here's the tea: the Display PLLs used for driving outputs vary by platform 🦋 like, every platform does its own thing, no cap.

some platforms have per-pipe or per-encoder dedicated PLLs 👑 — very "this is my PLL, mine only" energy. others? they let you use any PLL from a pool 💅 which is honestly iconic and flexible of them.

and in that pool scenario 🫶 it's totally possible that multiple pipes share a PLL — but only if their configurations match. iykyk, matching configs = sharing privileges unlocked 🔥

this file provides an abstraction over display PLLs ✨. the function intel_dpll_init initializes the PLLs for the given platform 🧚

the users of a PLL are tracked 📋 and that tracking is integrated with the atomic modset interface. and during an atomic operation, the required PLLs can be reserved for a given CRTC and encoder configuration by calling intel_dpll_reserve 🔒 and previously reserved PLLs can be released with intel_dpll_release 🔓 — so polite, so clean.

changes to the users are first staged in the atomic state 🙈 and then made effective by calling intel_dpll_swap_state during the atomic commit phase ⭐ like the glow-up happens at commit time, periodt 💜

✨ SEE ALSO ✨

the kernel file lives right here, bestie:

• ./drivers/gpu/drm/i915/display/intel_dpll_mgr.c 🎀

and the whole friend group of related pages, all of them, no skips 👇

• intel_get_dpll_by_id(9)
• intel_dpll_enable(9)
• intel_dpll_disable(9)
• intel_dpll_crtc_get(9)
• intel_dpll_crtc_put(9)
• intel_dpll_swap_state(9)
• icl_set_active_port_dpll(9)
• intel_dpll_init(9)
• intel_dpll_compute(9)
• intel_dpll_reserve(9)
• intel_dpll_release(9)
• intel_dpll_update_active(9)
• intel_dpll_get_freq(9)
• intel_dpll_get_hw_state(9)
• intel_dpll_dump_hw_state(9)
• intel_dpll_compare_hw_state(9)

and that's the whole page, bestie 🫶 this beauty comes from ./drivers/gpu/drm/i915/display and it's dated October 2026 ⭐ so go forth and reserve those PLLs responsibly 💖💅