1 files changed, 20 insertions, 5 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index e5daad5f75fb..5b205863b659 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -2936,9 +2936,9 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
         req = obj->last_read_req;
 
         /* Do this after OLR check to make sure we make forward progress polling
-         * on this IOCTL with a timeout <=0 (like busy ioctl)
+         * on this IOCTL with a timeout == 0 (like busy ioctl)
          */
-        if (args->timeout_ns <= 0) {
+        if (args->timeout_ns == 0) {
                 ret = -ETIME;
                 goto out;
         }
@@ -2948,7 +2948,8 @@ i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
         i915_gem_request_reference(req);
         mutex_unlock(&dev->struct_mutex);
 
-        ret = __i915_wait_request(req, reset_counter, true, &args->timeout_ns,
+        ret = __i915_wait_request(req, reset_counter, true,
+                                  args->timeout_ns > 0 ? &args->timeout_ns : NULL,
                                   file->driver_priv);
         mutex_lock(&dev->struct_mutex);
         i915_gem_request_unreference(req);
@@ -4792,6 +4793,9 @@ i915_gem_init_hw(struct drm_device *dev)
         if (INTEL_INFO(dev)->gen < 6 && !intel_enable_gtt())
                 return -EIO;
 
+        /* Double layer security blanket, see i915_gem_init() */
+        intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
+
         if (dev_priv->ellc_size)
                 I915_WRITE(HSW_IDICR, I915_READ(HSW_IDICR) | IDIHASHMSK(0xf));
 
@@ -4824,7 +4828,7 @@ i915_gem_init_hw(struct drm_device *dev)
         for_each_ring(ring, dev_priv, i) {
                 ret = ring->init_hw(ring);
                 if (ret)
-                        return ret;
+                        goto out;
         }
 
         for (i = 0; i < NUM_L3_SLICES(dev); i++)
@@ -4841,9 +4845,11 @@ i915_gem_init_hw(struct drm_device *dev)
                 DRM_ERROR("Context enable failed %d\n", ret);
                 i915_gem_cleanup_ringbuffer(dev);
 
-                return ret;
+                goto out;
         }
 
+out:
+        intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
         return ret;
 }
 
@@ -4877,6 +4883,14 @@ int i915_gem_init(struct drm_device *dev)
                 dev_priv->gt.stop_ring = intel_logical_ring_stop;
         }
 
+        /* This is just a security blanket to placate dragons.
+         * On some systems, we very sporadically observe that the first TLBs
+         * used by the CS may be stale, despite us poking the TLB reset. If
+         * we hold the forcewake during initialisation these problems
+         * just magically go away.
+         */
+        intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
+
         ret = i915_gem_init_userptr(dev);
         if (ret)
                 goto out_unlock;
@@ -4903,6 +4917,7 @@ int i915_gem_init(struct drm_device *dev)
         }
 
 out_unlock:
+        intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
         mutex_unlock(&dev->struct_mutex);
 
         return ret;