drm/i915: Require HW contexts (when possible)

v2: Fixed the botched locking on init_hw failure in i915_reset (Ville)
Call cleanup_ringbuffer on failed context create in init_hw (Ville)

v3: Add dev argument ti clean_ringbuffer
Reviewed-by: NKenneth Graunke <kenneth@whitecape.org>
Signed-off-by: NBen Widawsky <ben@bwidawsk.net>
Signed-off-by: NRodrigo Vivi <rodrigo.vivi@gmail.com>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.c

@@ -755,12 +755,9 @@ int i915_reset(struct drm_device *dev)
 	 */
 	if (drm_core_check_feature(dev, DRIVER_MODESET) ||
 			!dev_priv->ums.mm_suspended) {
-		bool hw_contexts_disabled = dev_priv->hw_contexts_disabled;
 		dev_priv->ums.mm_suspended = 0;
 
 		ret = i915_gem_init_hw(dev);
-		if (!hw_contexts_disabled && dev_priv->hw_contexts_disabled)
-			DRM_ERROR("HW contexts didn't survive reset\n");
 		mutex_unlock(&dev->struct_mutex);
 		if (ret) {
 			DRM_ERROR("Failed hw init on reset %d\n", ret);

drivers/gpu/drm/i915/i915_drv.h

@@ -1447,7 +1447,6 @@ typedef struct drm_i915_private {
 	struct drm_property *broadcast_rgb_property;
 	struct drm_property *force_audio_property;
 
-	bool hw_contexts_disabled;
 	uint32_t hw_context_size;
 	struct list_head context_list;
 
@@ -2151,7 +2150,7 @@ i915_gem_obj_ggtt_pin(struct drm_i915_gem_object *obj,
 }
 
 /* i915_gem_context.c */
-void i915_gem_context_init(struct drm_device *dev);
+int __must_check i915_gem_context_init(struct drm_device *dev);
 void i915_gem_context_fini(struct drm_device *dev);
 void i915_gem_context_close(struct drm_device *dev, struct drm_file *file);
 int i915_switch_context(struct intel_ring_buffer *ring,

drivers/gpu/drm/i915/i915_gem.c

@@ -4463,7 +4463,13 @@ i915_gem_init_hw(struct drm_device *dev)
 	 * XXX: There was some w/a described somewhere suggesting loading
 	 * contexts before PPGTT.
 	 */
-	i915_gem_context_init(dev);
+	ret = i915_gem_context_init(dev);
+	if (ret) {
+		i915_gem_cleanup_ringbuffer(dev);
+		DRM_ERROR("Context initialization failed %d\n", ret);
+		return ret;
+	}
+
 	if (dev_priv->mm.aliasing_ppgtt) {
 		ret = dev_priv->mm.aliasing_ppgtt->enable(dev);
 		if (ret) {

drivers/gpu/drm/i915/i915_gem_context.c

@@ -244,36 +244,34 @@ static int create_default_context(struct drm_i915_private *dev_priv)
 	return ret;
 }
 
-void i915_gem_context_init(struct drm_device *dev)
+int i915_gem_context_init(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
+	int ret;
 
-	if (!HAS_HW_CONTEXTS(dev)) {
-		dev_priv->hw_contexts_disabled = true;
-		DRM_DEBUG_DRIVER("Disabling HW Contexts; old hardware\n");
-		return;
-	}
+	if (!HAS_HW_CONTEXTS(dev))
+		return 0;
 
 	/* If called from reset, or thaw... we've been here already */
-	if (dev_priv->hw_contexts_disabled ||
-	    dev_priv->ring[RCS].default_context)
-		return;
+	if (dev_priv->ring[RCS].default_context)
+		return 0;
 
 	dev_priv->hw_context_size = round_up(get_context_size(dev), 4096);
 
 	if (dev_priv->hw_context_size > (1<<20)) {
-		dev_priv->hw_contexts_disabled = true;
 		DRM_DEBUG_DRIVER("Disabling HW Contexts; invalid size\n");
-		return;
+		return -E2BIG;
 	}
 
-	if (create_default_context(dev_priv)) {
-		dev_priv->hw_contexts_disabled = true;
-		DRM_DEBUG_DRIVER("Disabling HW Contexts; create failed\n");
-		return;
+	ret = create_default_context(dev_priv);
+	if (ret) {
+		DRM_DEBUG_DRIVER("Disabling HW Contexts; create failed %d\n",
+				 ret);
+		return ret;
 	}
 
 	DRM_DEBUG_DRIVER("HW context support initialized\n");
+	return 0;
 }
 
 void i915_gem_context_fini(struct drm_device *dev)
@@ -281,7 +279,7 @@ void i915_gem_context_fini(struct drm_device *dev)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct i915_hw_context *dctx = dev_priv->ring[RCS].default_context;
 
-	if (dev_priv->hw_contexts_disabled)
+	if (!HAS_HW_CONTEXTS(dev))
 		return;
 
 	/* The only known way to stop the gpu from accessing the hw context is
@@ -324,16 +322,16 @@ i915_gem_context_get_hang_stats(struct drm_device *dev,
 				struct drm_file *file,
 				u32 id)
 {
-	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_file_private *file_priv = file->driver_priv;
 	struct i915_hw_context *ctx;
 
 	if (id == DEFAULT_CONTEXT_ID)
 		return &file_priv->hang_stats;
 
-	ctx = NULL;
-	if (!dev_priv->hw_contexts_disabled)
-		ctx = i915_gem_context_get(file->driver_priv, id);
+	if (!HAS_HW_CONTEXTS(dev))
+		return ERR_PTR(-ENOENT);
+
+	ctx = i915_gem_context_get(file->driver_priv, id);
 	if (ctx == NULL)
 		return ERR_PTR(-ENOENT);
 
@@ -506,7 +504,7 @@ int i915_switch_context(struct intel_ring_buffer *ring,
 	struct drm_i915_private *dev_priv = ring->dev->dev_private;
 	struct i915_hw_context *to;
 
-	if (dev_priv->hw_contexts_disabled)
+	if (!HAS_HW_CONTEXTS(ring->dev))
 		return 0;
 
 	WARN_ON(!mutex_is_locked(&dev_priv->dev->struct_mutex));
@@ -531,7 +529,6 @@ int i915_switch_context(struct intel_ring_buffer *ring,
 int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
 				  struct drm_file *file)
 {
-	struct drm_i915_private *dev_priv = dev->dev_private;
 	struct drm_i915_gem_context_create *args = data;
 	struct drm_i915_file_private *file_priv = file->driver_priv;
 	struct i915_hw_context *ctx;
@@ -540,7 +537,7 @@ int i915_gem_context_create_ioctl(struct drm_device *dev, void *data,
 	if (!(dev->driver->driver_features & DRIVER_GEM))
 		return -ENODEV;
 
-	if (dev_priv->hw_contexts_disabled)
+	if (!HAS_HW_CONTEXTS(dev))
 		return -ENODEV;
 
 	ret = i915_mutex_lock_interruptible(dev);

drivers/gpu/drm/i915/i915_sysfs.c

@@ -181,13 +181,13 @@ i915_l3_write(struct file *filp, struct kobject *kobj,
 	int slice = (int)(uintptr_t)attr->private;
 	int ret;
 
+	if (!HAS_HW_CONTEXTS(drm_dev))
+		return -ENXIO;
+
 	ret = l3_access_valid(drm_dev, offset);
 	if (ret)
 		return ret;
 
-	if (dev_priv->hw_contexts_disabled)
-		return -ENXIO;
-
 	ret = i915_mutex_lock_interruptible(drm_dev);
 	if (ret)
 		return ret;