drm/i915: Wait for LVDS panel power cycle delay on reboot

Just like with eDP let's wait for the power sequencer power
cycle delay before we reboot the machine, as otherwise we
can't guarantee the panel's minimum power cycle delay will
be respected.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201001151640.14590-5-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

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

@@ -371,6 +371,15 @@ static void pch_post_disable_lvds(struct intel_atomic_state *state,
 	intel_disable_lvds(state, encoder, old_crtc_state, old_conn_state);
 }
 
+static void intel_lvds_shutdown(struct intel_encoder *encoder)
+{
+	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
+
+	if (intel_de_wait_for_clear(dev_priv, PP_STATUS(0), PP_CYCLE_DELAY_ACTIVE, 5000))
+		drm_err(&dev_priv->drm,
+			"timed out waiting for panel power cycle delay\n");
+}
+
 static enum drm_mode_status
 intel_lvds_mode_valid(struct drm_connector *connector,
 		      struct drm_display_mode *mode)
@@ -897,6 +906,7 @@ void intel_lvds_init(struct drm_i915_private *dev_priv)
 	intel_encoder->get_hw_state = intel_lvds_get_hw_state;
 	intel_encoder->get_config = intel_lvds_get_config;
 	intel_encoder->update_pipe = intel_panel_update_backlight;
+	intel_encoder->shutdown = intel_lvds_shutdown;
 	intel_connector->get_hw_state = intel_connector_get_hw_state;
 
 	intel_connector_attach_encoder(intel_connector, intel_encoder);