FAILED: patch "[PATCH] drm/i915: Fix ilk+ watermarks when disabling pipes" failed to apply to 4.14-stable tree

The patch below does not apply to the 4.14-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <[email protected]>
Date: Thu, 25 Oct 2018 16:05:36 +0300
Subject: [PATCH] drm/i915: Fix ilk+ watermarks when disabling pipes
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We're no longer programming any watermarks when we're disabling a pipe. That means ilk_wm_merge() & co. will keep considering the any pipe that is getting disabled as still enabled. Thus we either get no LP1+ watermakrs (ilk-ivb), or we get suboptimal ones (hsw-bdw).

This seems to have been broken by commit b6b178a77210 ("drm/i915:
Calculate ironlake intermediate watermarks correctly, v2."). Before that we apparently had some difference between the intermediate and optimal watermarks and so we would program the optiomal ones. Now intermediate and optimal are identical for disabled pipes and so we don't program either.

Fix this by programming the intermediate watermarks even for disabled pipes. We were already doing that for skl+. We'll leave out gmch platforms for now since those do the merging in a different manner and should work as is. We'll want to unify this eventually, but play it safe for now and just put in a FIXME.

index b8dfdbc9ca1f..23d8008a93bb 100644
@@ -12768,17 +12768,12 @@ static void intel_atomic_commit_tail(struct drm_atomic_state *state)
 			intel_check_cpu_fifo_underruns(dev_priv);
 			intel_check_pch_fifo_underruns(dev_priv);
 
-			if (!new_crtc_state->active) {
-				/*
-				 * Make sure we don't call initial_watermarks
-				 * for ILK-style watermark updates.
-				 *
-				 * No clue what this is supposed to achieve.
-				 */
-				if (INTEL_GEN(dev_priv) >= 9)
-					dev_priv->display.initial_watermarks(intel_state,
-									     to_intel_crtc_state(new_crtc_state));
-			}
+			/* FIXME unify this for all platforms */
+			if (!new_crtc_state->active &&
+			    !HAS_GMCH_DISPLAY(dev_priv) &&
+			    dev_priv->display.initial_watermarks)
+				dev_priv->display.initial_watermarks(intel_state,
+								     to_intel_crtc_state(new_crtc_state));
 		}
 	}