drm/i915: Pin fence for iomap

Acquire the fence register for the iomap in i915_vma_pin_iomap() on
behalf of the caller.

We probably want for the caller to specify whether the fence should be
pinned for their usage, but at the moment all callers do want the
associated fence, or none, so take it on their behalf.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171009084401.29090-1-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_vma.c

@@ -280,13 +280,16 @@ int i915_vma_bind(struct i915_vma *vma, enum i915_cache_level cache_level,
 void __iomem *i915_vma_pin_iomap(struct i915_vma *vma)
 {
 	void __iomem *ptr;
+	int err;
 
 	/* Access through the GTT requires the device to be awake. */
 	assert_rpm_wakelock_held(vma->vm->i915);
 
 	lockdep_assert_held(&vma->vm->i915->drm.struct_mutex);
-	if (WARN_ON(!i915_vma_is_map_and_fenceable(vma)))
-		return IO_ERR_PTR(-ENODEV);
+	if (WARN_ON(!i915_vma_is_map_and_fenceable(vma))) {
+		err = -ENODEV;
+		goto err;
+	}
 
 	GEM_BUG_ON(!i915_vma_is_ggtt(vma));
 	GEM_BUG_ON((vma->flags & I915_VMA_GLOBAL_BIND) == 0);
@@ -296,14 +299,38 @@ void __iomem *i915_vma_pin_iomap(struct i915_vma *vma)
 		ptr = io_mapping_map_wc(&i915_vm_to_ggtt(vma->vm)->mappable,
 					vma->node.start,
 					vma->node.size);
-		if (ptr == NULL)
-			return IO_ERR_PTR(-ENOMEM);
+		if (ptr == NULL) {
+			err = -ENOMEM;
+			goto err;
+		}
 
 		vma->iomap = ptr;
 	}
 
 	__i915_vma_pin(vma);
+
+	err = i915_vma_get_fence(vma);
+	if (err)
+		goto err_unpin;
+
+	i915_vma_pin_fence(vma);
+
 	return ptr;
+
+err_unpin:
+	__i915_vma_unpin(vma);
+err:
+	return IO_ERR_PTR(err);
+}
+
+void i915_vma_unpin_iomap(struct i915_vma *vma)
+{
+	lockdep_assert_held(&vma->obj->base.dev->struct_mutex);
+
+	GEM_BUG_ON(vma->iomap == NULL);
+
+	i915_vma_unpin_fence(vma);
+	i915_vma_unpin(vma);
 }
 
 void i915_vma_unpin_and_release(struct i915_vma **p_vma)