drm/i915: Introduce ilk_pch_pre_enable()

Complete the ilk pch modeset abstraction by adding ilk_pch_pre_enable().
I did the disable vs. post_disable split already for the disable
sequence, but the enable sequence was still left with the naked
ilk_fdi_pll_enable() call for some reason.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220124193136.2397-2-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

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

@@ -1858,10 +1858,7 @@ static void ilk_crtc_enable(struct intel_atomic_state *state,
 	intel_encoders_pre_enable(state, crtc);
 
 	if (new_crtc_state->has_pch_encoder) {
-		/* Note: FDI PLL enabling _must_ be done before we enable the
-		 * cpu pipes, hence this is separate from all the other fdi/pch
-		 * enabling. */
-		ilk_fdi_pll_enable(new_crtc_state);
+		ilk_pch_pre_enable(state, crtc);
 	} else {
 		assert_fdi_tx_disabled(dev_priv, pipe);
 		assert_fdi_rx_disabled(dev_priv, pipe);

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

@@ -211,6 +211,20 @@ static void ilk_disable_pch_transcoder(struct intel_crtc *crtc)
 	}
 }
 
+void ilk_pch_pre_enable(struct intel_atomic_state *state,
+			struct intel_crtc *crtc)
+{
+	const struct intel_crtc_state *crtc_state =
+		intel_atomic_get_new_crtc_state(state, crtc);
+
+	/*
+	 * Note: FDI PLL enabling _must_ be done before we enable the
+	 * cpu pipes, hence this is separate from all the other fdi/pch
+	 * enabling.
+	 */
+	ilk_fdi_pll_enable(crtc_state);
+}
+
 /*
  * Enable PCH resources required for PCH ports:
  *   - PCH PLLs

drivers/gpu/drm/i915/display/intel_pch_display.h

@@ -10,6 +10,8 @@ struct intel_atomic_state;
 struct intel_crtc;
 struct intel_crtc_state;
 
+void ilk_pch_pre_enable(struct intel_atomic_state *state,
+			struct intel_crtc *crtc);
 void ilk_pch_enable(struct intel_atomic_state *state,
 		    struct intel_crtc *crtc);
 void ilk_pch_disable(struct intel_atomic_state *state,