drm/i915: Make downclock deduction common for all panels

If one mode of a internal panel has more than one refresh rate, then a reduced
clock is found for the LFP (LVDS/eDP). This enables switching between low
and high frequency dynamically. Moving downclock calculation to intel_panel
so that it is common for LVDS and eDP.

Signed-off-by: Vandana Kannan <vandana.kannan@intel.com>
Signed-off-by: Pradeep Bhat <pradeep.bhat@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 5dea389..9f8b465 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -155,6 +155,7 @@
 
 struct intel_panel {
 	struct drm_display_mode *fixed_mode;
+	struct drm_display_mode *downclock_mode;
 	int fitting_mode;
 
 	/* backlight */
@@ -823,7 +824,10 @@
 void intel_panel_destroy_backlight(struct drm_connector *connector);
 void intel_panel_init_backlight_funcs(struct drm_device *dev);
 enum drm_connector_status intel_panel_detect(struct drm_device *dev);
-
+extern struct drm_display_mode *intel_find_panel_downclock(
+				struct drm_device *dev,
+				struct drm_display_mode *fixed_mode,
+				struct drm_connector *connector);
 
 /* intel_pm.c */
 void intel_init_clock_gating(struct drm_device *dev);