drm/i915/evict: Always switch away from the current context

Currently execlists is exempt from emitting a request to switch each
ring away from the current context over to the dev_priv->kernel_context
(for whatever reason, just under execlists the GGTT is unlikely to be as
fragmented, however the switch may help in some extreme cases). Extract
the switcher and enable it for execlsts as well, as we need to do so in
a later patch to force the context switch before suspend. (And since for
that switch we explicitly require the disposable kernel context, rename
the extracted function.)

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Mika Kuoppala <mika.kuoppala@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1468590980-6186-1-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_drv.h

@@ -3525,6 +3525,7 @@ void i915_gem_context_reset(struct drm_device *dev);
 int i915_gem_context_open(struct drm_device *dev, struct drm_file *file);
 void i915_gem_context_close(struct drm_device *dev, struct drm_file *file);
 int i915_switch_context(struct drm_i915_gem_request *req);
+int i915_gem_switch_to_kernel_context(struct drm_i915_private *dev_priv);
 void i915_gem_context_free(struct kref *ctx_ref);
 struct drm_i915_gem_object *
 i915_gem_alloc_context_obj(struct drm_device *dev, size_t size);

drivers/gpu/drm/i915/i915_gem_context.c

@@ -926,6 +926,35 @@ int i915_switch_context(struct drm_i915_gem_request *req)
 	return do_rcs_switch(req);
 }
 
+int i915_gem_switch_to_kernel_context(struct drm_i915_private *dev_priv)
+{
+	struct intel_engine_cs *engine;
+
+	for_each_engine(engine, dev_priv) {
+		struct drm_i915_gem_request *req;
+		int ret;
+
+		if (engine->last_context == NULL)
+			continue;
+
+		if (engine->last_context == dev_priv->kernel_context)
+			continue;
+
+		req = i915_gem_request_alloc(engine, dev_priv->kernel_context);
+		if (IS_ERR(req))
+			return PTR_ERR(req);
+
+		ret = 0;
+		if (!i915.enable_execlists)
+			ret = i915_switch_context(req);
+		i915_add_request_no_flush(req);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
 static bool contexts_enabled(struct drm_device *dev)
 {
 	return i915.enable_execlists || to_i915(dev)->hw_context_size;

drivers/gpu/drm/i915/i915_gem_evict.c

@@ -33,37 +33,6 @@
 #include "intel_drv.h"
 #include "i915_trace.h"
 
-static int switch_to_pinned_context(struct drm_i915_private *dev_priv)
-{
-	struct intel_engine_cs *engine;
-
-	if (i915.enable_execlists)
-		return 0;
-
-	for_each_engine(engine, dev_priv) {
-		struct drm_i915_gem_request *req;
-		int ret;
-
-		if (engine->last_context == NULL)
-			continue;
-
-		if (engine->last_context == dev_priv->kernel_context)
-			continue;
-
-		req = i915_gem_request_alloc(engine, dev_priv->kernel_context);
-		if (IS_ERR(req))
-			return PTR_ERR(req);
-
-		ret = i915_switch_context(req);
-		i915_add_request_no_flush(req);
-		if (ret)
-			return ret;
-	}
-
-	return 0;
-}
-
-
 static bool
 mark_free(struct i915_vma *vma, struct list_head *unwind)
 {
@@ -184,7 +153,7 @@ none:
 		struct drm_i915_private *dev_priv = to_i915(dev);
 
 		if (i915_is_ggtt(vm)) {
-			ret = switch_to_pinned_context(dev_priv);
+			ret = i915_gem_switch_to_kernel_context(dev_priv);
 			if (ret)
 				return ret;
 		}
@@ -303,7 +272,7 @@ int i915_gem_evict_vm(struct i915_address_space *vm, bool do_idle)
 		struct drm_i915_private *dev_priv = to_i915(vm->dev);
 
 		if (i915_is_ggtt(vm)) {
-			ret = switch_to_pinned_context(dev_priv);
+			ret = i915_gem_switch_to_kernel_context(dev_priv);
 			if (ret)
 				return ret;
 		}