struct intel_dpll_funcs {
        int (*crtc_compute_clock)(struct intel_atomic_state *state,
                                  struct intel_crtc *crtc);
+       int (*crtc_get_shared_dpll)(struct intel_atomic_state *state,
+                                   struct intel_crtc *crtc);
 };
 
 struct intel_limit {
 
 static int hsw_crtc_compute_clock(struct intel_atomic_state *state,
                                  struct intel_crtc *crtc)
+{
+       return 0;
+}
+
+static int hsw_crtc_get_shared_dpll(struct intel_atomic_state *state,
+                                   struct intel_crtc *crtc)
 {
        struct drm_i915_private *dev_priv = to_i915(state->base.dev);
        struct intel_crtc_state *crtc_state =
                intel_atomic_get_new_crtc_state(state, crtc);
        const struct intel_limit *limit;
        int refclk = 120000;
-       int ret;
 
        /* CPU eDP is the only output that doesn't need a PCH PLL of its own. */
        if (!crtc_state->has_pch_encoder)
        ilk_compute_dpll(crtc_state, &crtc_state->dpll,
                         &crtc_state->dpll);
 
+       return 0;
+}
+
+static int ilk_crtc_get_shared_dpll(struct intel_atomic_state *state,
+                                   struct intel_crtc *crtc)
+{
+       struct drm_i915_private *dev_priv = to_i915(state->base.dev);
+       struct intel_crtc_state *crtc_state =
+               intel_atomic_get_new_crtc_state(state, crtc);
+       int ret;
+
+       /* CPU eDP is the only output that doesn't need a PCH PLL of its own. */
+       if (!crtc_state->has_pch_encoder)
+               return 0;
+
        ret = intel_reserve_shared_dplls(state, crtc, NULL);
        if (ret) {
                drm_dbg_kms(&dev_priv->drm,
 
 static const struct intel_dpll_funcs hsw_dpll_funcs = {
        .crtc_compute_clock = hsw_crtc_compute_clock,
+       .crtc_get_shared_dpll = hsw_crtc_get_shared_dpll,
 };
 
 static const struct intel_dpll_funcs ilk_dpll_funcs = {
        .crtc_compute_clock = ilk_crtc_compute_clock,
+       .crtc_get_shared_dpll = ilk_crtc_get_shared_dpll,
 };
 
 static const struct intel_dpll_funcs chv_dpll_funcs = {
        return i915->dpll_funcs->crtc_compute_clock(state, crtc);
 }
 
+int intel_dpll_crtc_get_shared_dpll(struct intel_atomic_state *state,
+                                   struct intel_crtc *crtc)
+{
+       struct drm_i915_private *i915 = to_i915(state->base.dev);
+       struct intel_crtc_state *crtc_state =
+               intel_atomic_get_new_crtc_state(state, crtc);
+
+       drm_WARN_ON(&i915->drm, !intel_crtc_needs_modeset(crtc_state));
+
+       if (drm_WARN_ON(&i915->drm, crtc_state->shared_dpll))
+               return 0;
+
+       if (!crtc_state->hw.enable)
+               return 0;
+
+       if (!i915->dpll_funcs->crtc_get_shared_dpll)
+               return 0;
+
+       return i915->dpll_funcs->crtc_get_shared_dpll(state, crtc);
+}
+
 void
 intel_dpll_init_clock_hook(struct drm_i915_private *dev_priv)
 {