FAILED: patch "[PATCH] drm/i915/bdw: Add missing delay during L3 SQC credit" failed to apply to 4.7-stable tree

FAILED: patch "[PATCH] drm/i915/bdw: Add missing delay during L3 SQC credit" failed to apply to 4.7-stable tree

[gregkh]

The patch below does not apply to the 4.7-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 <stable@vger.kernel.org>.

thanks,

greg k-h

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

>From 48e5d68d28f00c0cadac5a830980ff3222781abb Mon Sep 17 00:00:00 2001
From: Imre Deak <imre.deak@intel.com>
Date: Tue, 3 May 2016 15:54:19 +0300
Subject: [PATCH] drm/i915/bdw: Add missing delay during L3 SQC credit
 programming
MIME-Version: 1.0
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BSpec requires us to wait ~100 clocks before re-enabling clock gating,
so make sure we do this.

CC: stable@vger.kernel.org
CC: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1462280061-1457-2-git-send-email-imre.deak@intel.com

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 2422ac38ce5d..227cd2d395a9 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6738,6 +6738,12 @@ static void broadwell_init_clock_gating(struct drm_device *dev)
 	misccpctl = I915_READ(GEN7_MISCCPCTL);
 	I915_WRITE(GEN7_MISCCPCTL, misccpctl & ~GEN7_DOP_CLOCK_GATE_ENABLE);
 	I915_WRITE(GEN8_L3SQCREG1, BDW_WA_L3SQCREG1_DEFAULT);
+	/*
+	 * Wait at least 100 clocks before re-enabling clock gating. See
+	 * the definition of L3SQCREG1 in BSpec.
+	 */
+	POSTING_READ(GEN8_L3SQCREG1);
+	udelay(1);
 	I915_WRITE(GEN7_MISCCPCTL, misccpctl);
 
 	/*