Forces LVDS downclock with module parameter. Module paramter is the dot clock in Khz
diff -uNrp a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
--- a/drivers/gpu/drm/i915/i915_drv.c	2012-12-10 22:30:57.000000000 -0500
+++ b/drivers/gpu/drm/i915/i915_drv.c	2012-12-27 16:21:43.607099597 -0500
@@ -90,6 +90,12 @@ MODULE_PARM_DESC(lvds_channel_mode,
 		 "Specify LVDS channel mode "
 		 "(0=probe BIOS [default], 1=single-channel, 2=dual-channel)");
 
+unsigned int i915_lvds_force_downclock __read_mostly = 0;
+module_param_named(lvds_force_downclock, i915_lvds_force_downclock, int, 0444);
+MODULE_PARM_DESC(lvds_force_downclock,
+		 "Force lvds panel downclock to be on with a the "
+		 "dotclock given");
+
 int i915_panel_use_ssc __read_mostly = -1;
 module_param_named(lvds_use_ssc, i915_panel_use_ssc, int, 0600);
 MODULE_PARM_DESC(lvds_use_ssc,
diff -uNrp a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
--- a/drivers/gpu/drm/i915/i915_drv.h	2012-12-10 22:30:57.000000000 -0500
+++ b/drivers/gpu/drm/i915/i915_drv.h	2012-12-27 16:42:25.968568436 -0500
@@ -1210,6 +1210,7 @@ extern int i915_panel_ignore_lid __read_
 extern unsigned int i915_powersave __read_mostly;
 extern int i915_semaphores __read_mostly;
 extern unsigned int i915_lvds_downclock __read_mostly;
+extern unsigned int i915_lvds_force_downclock __read_mostly;
 extern int i915_lvds_channel_mode __read_mostly;
 extern int i915_panel_use_ssc __read_mostly;
 extern int i915_vbt_sdvo_panel_type __read_mostly;
diff -uNrp a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
--- a/drivers/gpu/drm/i915/intel_lvds.c	2012-12-10 22:30:57.000000000 -0500
+++ b/drivers/gpu/drm/i915/intel_lvds.c	2012-12-27 16:21:43.613099523 -0500
@@ -838,6 +838,15 @@ static void intel_find_lvds_downclock(st
 			      "Normal clock %dKhz, downclock %dKhz\n",
 			      fixed_mode->clock, temp_downclock);
 	}
+	else if (i915_lvds_force_downclock > 0 && i915_lvds_downclock) {
+		/* Using user set downclock for LVDS. */
+		dev_priv->lvds_downclock_avail = 1;
+		temp_downclock = i915_lvds_force_downclock;
+		dev_priv->lvds_downclock = temp_downclock;
+		DRM_DEBUG_KMS("LVDS downclock forced by user. "
+				"Normal clock %dKhz, downclock %dKhz\n",
+				fixed_mode->clock, temp_downclock);
+	}
 }
 
 /*