FAILED: patch "[PATCH] drm/i915: Extend the async flip VT-d w/a to skl/bxt" failed to apply to 5.15-stable tree

The patch below does not apply to the 5.15-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 99bac3063e8e0f437b04897a399b9394919d1a79 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <[email protected]>
Date: Thu, 30 Sep 2021 22:09:42 +0300
Subject: [PATCH] drm/i915: Extend the async flip VT-d w/a to skl/bxt
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Looks like skl/bxt/derivatives also need the plane stride stretch w/a when using async flips and VT-d is enabled, or else we get corruption on screen. To my surprise this was even documented in bspec, but only as a note on the CHICHKEN_PIPESL register description rather than on the w/a list.

So very much the same thing as on HSW/BDW, except the bits moved yet again.

index f90fe39cf8ca..ecbb3d141632 100644
@@ -77,6 +77,8 @@ struct intel_wm_config {
 
 static void gen9_init_clock_gating(struct drm_i915_private *dev_priv)
 {
+	enum pipe pipe;
+
 	if (HAS_LLC(dev_priv)) {
 		/*
 		 * WaCompressedResourceDisplayNewHashMode:skl,kbl

@@ -90,6 +92,16 @@ static void gen9_init_clock_gating(struct drm_i915_private *dev_priv)
 			   SKL_DE_COMPRESSED_HASH_MODE);
 	}
 
+	for_each_pipe(dev_priv, pipe) {
+		/*
+		 * "Plane N strech max must be programmed to 11b (x1)
+		 *  when Async flips are enabled on that plane."
+		 */
+		if (!IS_GEMINILAKE(dev_priv) && intel_vtd_active())
+			intel_uncore_rmw(&dev_priv->uncore, CHICKEN_PIPESL_1(pipe),
+					 SKL_PLANE1_STRETCH_MAX_MASK, SKL_PLANE1_STRETCH_MAX_X1);
+	}
+
 	/* See Bspec note for PSR2_CTL bit 31, Wa#828:skl,bxt,kbl,cfl */
 	intel_uncore_write(&dev_priv->uncore, CHICKEN_PAR1_1,
 		   intel_uncore_read(&dev_priv->uncore, CHICKEN_PAR1_1) | SKL_EDP_PSR_FIX_RDWRAP);