From 213f1bd035edc36f8d68c028d1b79675cd167d1d Mon Sep 17 00:00:00 2001
From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Date: Tue, 19 Sep 2017 14:14:19 +0200
Subject: [PATCH] drm/i915: Skip vblank waits for cursor updates when watermarks dont need updating
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Git-commit: 213f1bd035edc36f8d68c028d1b79675cd167d1d
Patch-mainline: v4.15-rc1
References: FATE#322643 bsc#1055900

In legacy cursor updates we need the extra vblank waits if we update
watermarks, and then we cannot skip the vblank for cursors.

This is why for < gen9 we disabled the cursor fastpath, but we can skip
the wait when post vblank watermarks are untouched.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170919121419.13708-2-maarten.lankhorst@linux.intel.com
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/i915/intel_display.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -12566,8 +12566,16 @@ static int intel_atomic_commit(struct dr
 	 * FIXME doing watermarks and fb cleanup from a vblank worker
 	 * (assuming we had any) would solve these problems.
 	 */
-	if (INTEL_GEN(dev_priv) < 9)
-		state->legacy_cursor_update = false;
+	if (INTEL_GEN(dev_priv) < 9 && state->legacy_cursor_update) {
+		struct intel_crtc_state *new_crtc_state;
+		struct intel_crtc *crtc;
+		int i;
+
+		for_each_new_intel_crtc_in_state(intel_state, crtc, new_crtc_state, i)
+			if (new_crtc_state->wm.need_postvbl_update ||
+			    new_crtc_state->update_wm_post)
+				state->legacy_cursor_update = false;
+	}
 
 	ret = intel_atomic_prepare_commit(dev, state);
 	if (ret) {