drm/i915: Queue the idling context switch after all other timelines

Before suspend, we wait for the switch to the kernel context. In order
for all the other context images to be complete upon suspend, that
switch must be the last operation by the GPU (i.e. this idling request
must not overtake any pending requests). To make this request execute last,
we make it depend on every other inflight request.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161028125858.23563-24-chris@chris-wilson.co.uk

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 525360219bbb..5ea46a7d991f 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -4362,6 +4362,15 @@ void __i915_gem_object_release_unless_active(struct drm_i915_gem_object *obj)
 		i915_gem_object_put(obj);
 }
 
+static void assert_kernel_context_is_current(struct drm_i915_private *dev_priv)
+{
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+
+	for_each_engine(engine, dev_priv, id)
+		GEM_BUG_ON(engine->last_context != dev_priv->kernel_context);
+}
+
 int i915_gem_suspend(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = to_i915(dev);
@@ -4391,6 +4400,7 @@ int i915_gem_suspend(struct drm_device *dev)
 
 	i915_gem_retire_requests(dev_priv);
 
+	assert_kernel_context_is_current(dev_priv);
 	i915_gem_context_lost(dev_priv);
 	mutex_unlock(&dev->struct_mutex);