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/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
index 254e2f6..56d1001 100644
--- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
+++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
@@ -530,18 +530,13 @@
 
 	if (has_fenced_gpu_access) {
 		if (entry->flags & EXEC_OBJECT_NEEDS_FENCE) {
-			if (obj->tiling_mode) {
-				ret = i915_gem_object_get_fence(obj, ring);
-				if (ret)
-					goto err_unpin;
+			ret = i915_gem_object_get_fence(obj, ring);
+			if (ret)
+				goto err_unpin;
 
+			if (i915_gem_object_pin_fence(obj))
 				entry->flags |= __EXEC_OBJECT_HAS_FENCE;
-				i915_gem_object_pin_fence(obj);
-			} else {
-				ret = i915_gem_object_put_fence(obj);
-				if (ret)
-					goto err_unpin;
-			}
+
 			obj->pending_fenced_gpu_access = true;
 		}
 	}