2 files changed, 24 insertions, 5 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 0c07a755b3a3..7edb5b9d5792 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2267,8 +2267,6 @@ i915_gem_object_get_fence_reg(struct drm_gem_object *obj)
                                     fence_list) {
                         old_obj = old_obj_priv->obj;
 
-                        reg = &dev_priv->fence_regs[old_obj_priv->fence_reg];
-
                         if (old_obj_priv->pin_count)
                                 continue;
 
@@ -2290,8 +2288,11 @@ i915_gem_object_get_fence_reg(struct drm_gem_object *obj)
                          */
                         i915_gem_object_flush_gpu_write_domain(old_obj);
                         ret = i915_gem_object_wait_rendering(old_obj);
-                        if (ret != 0)
+                        if (ret != 0) {
+                                drm_gem_object_unreference(old_obj);
                                 return ret;
+                        }
+
                         break;
                 }
 
@@ -2299,10 +2300,14 @@ i915_gem_object_get_fence_reg(struct drm_gem_object *obj)
                  * Zap this virtual mapping so we can set up a fence again
                  * for this object next time we need it.
                  */
-                i915_gem_release_mmap(reg->obj);
+                i915_gem_release_mmap(old_obj);
+
                 i = old_obj_priv->fence_reg;
+                reg = &dev_priv->fence_regs[i];
+
                 old_obj_priv->fence_reg = I915_FENCE_REG_NONE;
                 list_del_init(&old_obj_priv->fence_list);
+
                 drm_gem_object_unreference(old_obj);
         }
 
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 3fadb5358858..748ed50c55ca 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -2005,7 +2005,21 @@ static void igd_enable_cxsr(struct drm_device *dev, unsigned long clock,
         return;
 }
 
-const static int latency_ns = 3000; /* default for non-igd platforms */
+/*
+ * Latency for FIFO fetches is dependent on several factors:
+ *   - memory configuration (speed, channels)
+ *   - chipset
+ *   - current MCH state
+ * It can be fairly high in some situations, so here we assume a fairly
+ * pessimal value.  It's a tradeoff between extra memory fetches (if we
+ * set this value too high, the FIFO will fetch frequently to stay full)
+ * and power consumption (set it too low to save power and we might see
+ * FIFO underruns and display "flicker").
+ *
+ * A value of 5us seems to be a good balance; safe for very low end
+ * platforms but not overly aggressive on lower latency configs.
+ */
+const static int latency_ns = 5000;
 
 static int intel_get_fifo_size(struct drm_device *dev, int plane)
 {