drm/i915: Refactor get_fence() to use the common fence writing routine

We can also take advantage of the new 'no retire' mode for seqno waiting
to avoid having to take a reference on the old fence object whilst
flushing an existing fence.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 27 insertions, 43 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e09ac3a95308..7bc4a40132ad 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2361,7 +2361,7 @@ i915_gem_object_flush_fence(struct drm_i915_gem_object *obj)
         if (obj->last_fenced_seqno) {
                 ret = i915_wait_request(obj->ring,
                                         obj->last_fenced_seqno,
-                                        true);
+                                        false);
                 if (ret)
                         return ret;
 
@@ -2449,63 +2449,47 @@ i915_gem_object_get_fence(struct drm_i915_gem_object *obj)
 {
         struct drm_device *dev = obj->base.dev;
         struct drm_i915_private *dev_priv = dev->dev_private;
+        bool enable = obj->tiling_mode != I915_TILING_NONE;
         struct drm_i915_fence_reg *reg;
         int ret;
 
-        if (obj->tiling_mode == I915_TILING_NONE)
-                return i915_gem_object_put_fence(obj);
+        /* Have we updated the tiling parameters upon the object and so
+         * will need to serialise the write to the associated fence register?
+         */
+        if (obj->tiling_changed) {
+                ret = i915_gem_object_flush_fence(obj);
+                if (ret)
+                        return ret;
+        }
 
         /* Just update our place in the LRU if our fence is getting reused. */
         if (obj->fence_reg != I915_FENCE_REG_NONE) {
                 reg = &dev_priv->fence_regs[obj->fence_reg];
-                list_move_tail(&reg->lru_list, &dev_priv->mm.fence_list);
+                if (!obj->tiling_changed) {
+                        list_move_tail(&reg->lru_list,
+                                       &dev_priv->mm.fence_list);
+                        return 0;
+                }
+        } else if (enable) {
+                reg = i915_find_fence_reg(dev);
+                if (reg == NULL)
+                        return -EDEADLK;
+
+                if (reg->obj) {
+                        struct drm_i915_gem_object *old = reg->obj;
 
-                if (obj->tiling_changed) {
-                        ret = i915_gem_object_flush_fence(obj);
+                        ret = i915_gem_object_flush_fence(old);
                         if (ret)
                                 return ret;
 
-                        goto update;
+                        i915_gem_object_fence_lost(old);
                 }
-
+        } else
                 return 0;
-        }
-
-        reg = i915_find_fence_reg(dev);
-        if (reg == NULL)
-                return -EDEADLK;
-
-        ret = i915_gem_object_flush_fence(obj);
-        if (ret)
-                return ret;
-
-        if (reg->obj) {
-                struct drm_i915_gem_object *old = reg->obj;
 
-                drm_gem_object_reference(&old->base);
-
-                if (old->tiling_mode)
-                        i915_gem_release_mmap(old);
-
-                ret = i915_gem_object_flush_fence(old);
-                if (ret) {
-                        drm_gem_object_unreference(&old->base);
-                        return ret;
-                }
-
-                old->fence_reg = I915_FENCE_REG_NONE;
-                old->last_fenced_seqno = 0;
-
-                drm_gem_object_unreference(&old->base);
-        }
-
-        reg->obj = obj;
-        list_move_tail(&reg->lru_list, &dev_priv->mm.fence_list);
-        obj->fence_reg = reg - dev_priv->fence_regs;
-
-update:
+        i915_gem_object_update_fence(obj, reg, enable);
         obj->tiling_changed = false;
-        i915_gem_write_fence(dev, reg - dev_priv->fence_regs, obj);
+
         return 0;
 }