FAILED: patch "[PATCH] drm/i915: Update watermark state correctly in" 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: Maarten Lankhorst <[email protected]>
Date: Fri, 10 Nov 2017 12:34:53 +0100
Subject: [PATCH] drm/i915: Update watermark state correctly in
sanitize_watermarks
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We no longer use intel_crtc->wm.active for watermarks any more, which was incorrect. But this uncovered a bug in sanitize_watermarks(), which meant that we wrote the correct watermarks, but the next update would still use the wrong hw watermarks for calculating. This caused all further updates to fail with -EINVAL and the log would reveal an error like the one below:

[   10.043902] [drm:ilk_validate_wm_level.part.8 [i915]] Sprite WM0 too large 56 (max 0)
[   10.043960] [drm:ilk_validate_pipe_wm [i915]] LP0 watermark invalid
[   10.044030] [drm:intel_crtc_atomic_check [i915]] No valid intermediate pipe watermarks are possible

index 5c7540f3f5dc..63c8b9ccb31e 100644
@@ -14443,6 +14443,8 @@ static void sanitize_watermarks(struct drm_device *dev)
 
 		cs->wm.need_postvbl_update = true;
 		dev_priv->display.optimize_watermarks(intel_state, cs);
+
+		to_intel_crtc_state(crtc->state)->wm = cs->wm;
 	}
 
 put_state: