FAILED: patch "[PATCH] drm/i915: Wait up to 3ms for the pcu to ack the cdclk change" failed to apply to 4.4-stable tree

FAILED: patch "[PATCH] drm/i915: Wait up to 3ms for the pcu to ack the cdclk change" failed to apply to 4.4-stable tree

[gregkh]

The patch below does not apply to the 4.4-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 848496e5902833600f7992f4faa82dc1546051ba Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ville=20Syrj=C3=A4l=C3=A4?= <ville.syrjala@linux.intel.com>
Date: Wed, 13 Jul 2016 16:32:03 +0300
Subject: [PATCH] drm/i915: Wait up to 3ms for the pcu to ack the cdclk change
 request on SKL
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Bspec tells us to keep bashing the PCU for up to 3ms when trying to
inform it about an upcoming change in the cdclk frequency. Currently
we only keep at it for 15*10usec (+ whatever delays gets added by
the sandybridge_pcode_read() itself). Let's change the limit to 3ms.

I decided to keep 10 usec delay per iteration for now, even though
the spec doesn't really tell us to do that.

Cc: stable@vger.kernel.org
Fixes: 5d96d8afcfbb ("drm/i915/skl: Deinit/init the display at suspend/resume")
Cc: David Weinehall <david.weinehall@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1468416723-23440-1-git-send-email-ville.syrjala@linux.intel.com
Tested-by: David Weinehall <david.weinehall@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 78beb7e9d384..c4c1c85366de 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5691,15 +5691,7 @@ static bool skl_cdclk_pcu_ready(struct drm_i915_private *dev_priv)
 
 static bool skl_cdclk_wait_for_pcu_ready(struct drm_i915_private *dev_priv)
 {
-	unsigned int i;
-
-	for (i = 0; i < 15; i++) {
-		if (skl_cdclk_pcu_ready(dev_priv))
-			return true;
-		udelay(10);
-	}
-
-	return false;
+	return _wait_for(skl_cdclk_pcu_ready(dev_priv), 3000, 10) == 0;
 }
 
 static void skl_set_cdclk(struct drm_i915_private *dev_priv, int cdclk, int vco)