drm/i915: Reorganise rules for get_fence/put_fence

By simplifying the rules to calling get_fence when writing to the
through the GTT in a tiled manner, and calling put_fence before writing
to the object through the GTT in a linear manner, the code becomes
clearer and there is less chance of making a mistake.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
[danvet: fixed up conflict with ppgtt code and spelling in a new
comment.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 37514a5..9dfa1fa 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2152,13 +2152,11 @@
 	 * framebuffer compression.  For simplicity, we always install
 	 * a fence as the cost is not that onerous.
 	 */
-	if (obj->tiling_mode != I915_TILING_NONE) {
-		ret = i915_gem_object_get_fence(obj, pipelined);
-		if (ret)
-			goto err_unpin;
+	ret = i915_gem_object_get_fence(obj, pipelined);
+	if (ret)
+		goto err_unpin;
 
-		i915_gem_object_pin_fence(obj);
-	}
+	i915_gem_object_pin_fence(obj);
 
 	dev_priv->mm.interruptible = true;
 	return 0;