drm/i915: Reassign DPLLs only for crtcs going throug .compute_config()

Only reassign the pipe's DPLL if it's going through a full
.compute_config() cycle. If OTOH it's just getting modeset
eg. in order to change cdclk there doesn't seem much point in
picking a new DPLL for it.

This should also prevent .get_dplls() from seeing a funky port_clock
for DP even in cases where the readout produces a non-standard
clock and we (for some reason) have decided to not fully recompute
the state to remedy the situation.
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220907091057.11572-7-ville.syrjala@linux.intel.com

drivers/gpu/drm/i915/display/intel_display.c

@@ -6066,20 +6066,6 @@ void intel_crtc_update_active_timings(const struct intel_crtc_state *crtc_state)
 	}
 }
 
-static void intel_modeset_clear_plls(struct intel_atomic_state *state)
-{
-	struct intel_crtc_state *new_crtc_state;
-	struct intel_crtc *crtc;
-	int i;
-
-	for_each_new_intel_crtc_in_state(state, crtc, new_crtc_state, i) {
-		if (!intel_crtc_needs_modeset(new_crtc_state))
-			continue;
-
-		intel_release_shared_dplls(state, crtc);
-	}
-}
-
 /*
  * This implements the workaround described in the "notes" section of the mode
  * set sequence documentation. When going from no pipes or single pipe to
@@ -6913,6 +6899,7 @@ static int intel_atomic_check(struct drm_device *dev,
 			if (ret)
 				goto fail;
 
+			intel_release_shared_dplls(state, crtc);
 			continue;
 		}
 
@@ -6960,8 +6947,6 @@ static int intel_atomic_check(struct drm_device *dev,
 		ret = intel_modeset_calc_cdclk(state);
 		if (ret)
 			return ret;
-
-		intel_modeset_clear_plls(state);
 	}
 
 	ret = intel_atomic_check_crtcs(state);

drivers/gpu/drm/i915/display/intel_dpll.c

@@ -1436,11 +1436,9 @@ int intel_dpll_crtc_get_shared_dpll(struct intel_atomic_state *state,
 	int ret;
 
 	drm_WARN_ON(&i915->drm, !intel_crtc_needs_modeset(crtc_state));
+	drm_WARN_ON(&i915->drm, !crtc_state->hw.enable && crtc_state->shared_dpll);
 
-	if (drm_WARN_ON(&i915->drm, crtc_state->shared_dpll))
-		return 0;
-
-	if (!crtc_state->hw.enable)
+	if (!crtc_state->hw.enable || crtc_state->shared_dpll)
 		return 0;
 
 	if (!i915->display.funcs.dpll->crtc_get_shared_dpll)