drm/i915: Track gpu fence usage

Track if the gpu requires the fence for the execution of a batch buffer
and so only wait upon the retirement of the object's last rendering
seqno if the fence is in use by the GPU.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

2 files changed, 10 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 790ffec135df..6e22be4f3585 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -128,6 +128,7 @@ struct drm_i915_master_private {
 struct drm_i915_fence_reg {
         struct drm_gem_object *obj;
         struct list_head lru_list;
+        bool gpu;
 };
 
 struct sdvo_device_mapping {
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index b242530ffcbd..a5d5751bad30 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2461,7 +2461,9 @@ i915_gem_object_put_fence_reg(struct drm_gem_object *obj,
                               bool interruptible)
 {
         struct drm_device *dev = obj->dev;
+        struct drm_i915_private *dev_priv = dev->dev_private;
         struct drm_i915_gem_object *obj_priv = to_intel_bo(obj);
+        struct drm_i915_fence_reg *reg;
 
         if (obj_priv->fence_reg == I915_FENCE_REG_NONE)
                 return 0;
@@ -2476,7 +2478,8 @@ i915_gem_object_put_fence_reg(struct drm_gem_object *obj,
          * therefore we must wait for any outstanding access to complete
          * before clearing the fence.
          */
-        if (INTEL_INFO(dev)->gen < 4) {
+        reg = &dev_priv->fence_regs[obj_priv->fence_reg];
+        if (reg->gpu) {
                 int ret;
 
                 ret = i915_gem_object_flush_gpu_write_domain(obj, true);
@@ -2486,6 +2489,8 @@ i915_gem_object_put_fence_reg(struct drm_gem_object *obj,
                 ret = i915_gem_object_wait_rendering(obj, interruptible);
                 if (ret)
                         return ret;
+
+                reg->gpu = false;
         }
 
         i915_gem_object_flush_gtt_write_domain(obj);
@@ -3180,11 +3185,13 @@ i915_gem_object_pin_and_relocate(struct drm_gem_object *obj,
          * properly handle blits to/from tiled surfaces.
          */
         if (need_fence) {
-                ret = i915_gem_object_get_fence_reg(obj, false);
+                ret = i915_gem_object_get_fence_reg(obj, true);
                 if (ret != 0) {
                         i915_gem_object_unpin(obj);
                         return ret;
                 }
+
+                dev_priv->fence_regs[obj_priv->fence_reg].gpu = true;
         }
 
         entry->offset = obj_priv->gtt_offset;