drm/i915: don't always do full mode sets when infoframes are enabled

Partial revert of

commit 20664591
Author: Jesse Barnes <jbarnes@virtuousgeek.org>
Date:   Wed Nov 5 14:26:09 2014 -0800

    drm/i915: check for audio and infoframe changes across mode sets v2

References: https://bugs.freedesktop.org/show_bug.cgi?id=86683Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Tested-by: Li Xu <li.l.xu@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>

drivers/gpu/drm/i915/intel_display.c

@@ -11583,10 +11583,12 @@ static int intel_crtc_set_config(struct drm_mode_set *set)
 		    to_intel_crtc(set->crtc)->config.has_audio)
 			config->mode_changed = true;
 
-		/* Force mode sets for any infoframe stuff */
-		if (pipe_config->has_infoframe ||
-		    to_intel_crtc(set->crtc)->config.has_infoframe)
-			config->mode_changed = true;
+		/*
+		 * Note we have an issue here with infoframes: current code
+		 * only updates them on the full mode set path per hw
+		 * requirements.  So here we should be checking for any
+		 * required changes and forcing a mode set.
+		 */
 	}
 
 	/* set_mode will free it in the mode_changed case */