FAILED: patch "[PATCH] drm/i915/gen9: fix the WM memory bandwidth WA for Y tiling" failed to apply to 4.9-stable tree

The patch below does not apply to the 4.9-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: Paulo Zanoni <[email protected]>
Date: Tue, 8 Nov 2016 18:22:11 -0200
Subject: [PATCH] drm/i915/gen9: fix the WM memory bandwidth WA for Y tiling
cases

The previous spec version said "double Ytile planes minimum lines", and I interpreted this as referring to what the spec calls "Y tile minimum", but in fact it was referring to what the spec calls "Minimum Scanlines for Y tile". I noticed that Mahesh Kumar had a different interpretation, so I sent and email to the spec authors and got clarification on the correct meaning. Also, BSpec was updated and should be clear now.

index 35c4afd2e143..f1ef9559014c 100644
@@ -3626,6 +3626,9 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
 		y_min_scanlines = 4;
 	}
 
+	if (apply_memory_bw_wa)
+		y_min_scanlines *= 2;
+
 	plane_bytes_per_line = width * cpp;
 	if (fb->modifier[0] == I915_FORMAT_MOD_Y_TILED ||
 	    fb->modifier[0] == I915_FORMAT_MOD_Yf_TILED) {

@@ -3646,8 +3649,6 @@ static int skl_compute_plane_wm(const struct drm_i915_private *dev_priv,
 				 plane_blocks_per_line);
 
 	y_tile_minimum = plane_blocks_per_line * y_min_scanlines;
-	if (apply_memory_bw_wa)
-		y_tile_minimum *= 2;
 
 	if (fb->modifier[0] == I915_FORMAT_MOD_Y_TILED ||
 	    fb->modifier[0] == I915_FORMAT_MOD_Yf_TILED) {