drm/i915: Fix retrieval of hangcheck stats

The default context is always supported (as it contains the global
hangcheck stats) and the contexts for hangcheck are not limited
to any ring.

References: https://bugs.freedesktop.org/show_bug.cgi?id=65845
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -1860,7 +1860,7 @@ static inline void i915_gem_context_unreference(struct i915_hw_context *ctx)
 }
 
 struct i915_ctx_hang_stats * __must_check
-i915_gem_context_get_hang_stats(struct intel_ring_buffer *ring,
+i915_gem_context_get_hang_stats(struct drm_device *dev,
 				struct drm_file *file,
 				u32 id);
 int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,

drivers/gpu/drm/i915/i915_gem_context.c

@@ -304,31 +304,24 @@ static int context_idr_cleanup(int id, void *p, void *data)
 }
 
 struct i915_ctx_hang_stats *
-i915_gem_context_get_hang_stats(struct intel_ring_buffer *ring,
+i915_gem_context_get_hang_stats(struct drm_device *dev,
 				struct drm_file *file,
 				u32 id)
 {
-	struct drm_i915_private *dev_priv = ring->dev->dev_private;
+	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_file_private *file_priv = file->driver_priv;
-	struct i915_hw_context *to;
-
-	if (dev_priv->hw_contexts_disabled)
-		return ERR_PTR(-ENOENT);
-
-	if (ring->id != RCS)
-		return ERR_PTR(-EINVAL);
-
-	if (file == NULL)
-		return ERR_PTR(-EINVAL);
+	struct i915_hw_context *ctx;
 
 	if (id == DEFAULT_CONTEXT_ID)
 		return &file_priv->hang_stats;
 
-	to = i915_gem_context_get(file->driver_priv, id);
-	if (to == NULL)
+	ctx = NULL;
+	if (!dev_priv->hw_contexts_disabled)
+		ctx = i915_gem_context_get(file->driver_priv, id);
+	if (ctx == NULL)
 		return ERR_PTR(-ENOENT);
 
-	return &to->hang_stats;
+	return &ctx->hang_stats;
 }
 
 void i915_gem_context_close(struct drm_device *dev, struct drm_file *file)