drm/i915: Move engine->submit_request selection to a vfunc

It turns out that we may want to restore the original
engine->submit_request (and engine->schedule) callbacks from more than
just the guc <-> execlists transition. Move this to a vfunc so we can
have a common interface.

v2: Move initial selection to intel_engines_init_common(), repaint vfunc
with engine->set_default_submission (and a similar colour for the
helper).
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170316171305.12972-2-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_guc_submission.c

@@ -1136,7 +1136,7 @@ void i915_guc_submission_disable(struct drm_i915_private *dev_priv)
 		return;
 
 	/* Revert back to manual ELSP submission */
-	intel_execlists_enable_submission(dev_priv);
+	intel_engines_reset_default_submission(dev_priv);
 }
 
 void i915_guc_submission_fini(struct drm_i915_private *dev_priv)

drivers/gpu/drm/i915/intel_engine_cs.c

@@ -193,6 +193,7 @@ int intel_engines_init(struct drm_i915_private *dev_priv)
 			goto cleanup;
 		}
 
+		GEM_BUG_ON(!engine->submit_request);
 		mask |= ENGINE_MASK(id);
 	}
 
@@ -343,6 +344,8 @@ int intel_engine_init_common(struct intel_engine_cs *engine)
 {
 	int ret;
 
+	engine->set_default_submission(engine);
+
 	/* We may need to do things with the shrinker which
 	 * require us to immediately switch back to the default
 	 * context. This can cause a problem as pinning the
@@ -1116,6 +1119,15 @@ bool intel_engines_are_idle(struct drm_i915_private *dev_priv)
 	return true;
 }
 
+void intel_engines_reset_default_submission(struct drm_i915_private *i915)
+{
+	struct intel_engine_cs *engine;
+	enum intel_engine_id id;
+
+	for_each_engine(engine, i915, id)
+		engine->set_default_submission(engine);
+}
+
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 #include "selftests/mock_engine.c"
 #endif

drivers/gpu/drm/i915/intel_lrc.c

@@ -1558,15 +1558,10 @@ void intel_logical_ring_cleanup(struct intel_engine_cs *engine)
 	kfree(engine);
 }
 
-void intel_execlists_enable_submission(struct drm_i915_private *dev_priv)
+static void execlists_set_default_submission(struct intel_engine_cs *engine)
 {
-	struct intel_engine_cs *engine;
-	enum intel_engine_id id;
-
-	for_each_engine(engine, dev_priv, id) {
 	engine->submit_request = execlists_submit_request;
 	engine->schedule = execlists_schedule;
-	}
 }
 
 static void
@@ -1584,8 +1579,8 @@ logical_ring_default_vfuncs(struct intel_engine_cs *engine)
 	engine->emit_flush = gen8_emit_flush;
 	engine->emit_breadcrumb = gen8_emit_breadcrumb;
 	engine->emit_breadcrumb_sz = gen8_emit_breadcrumb_sz;
-	engine->submit_request = execlists_submit_request;
-	engine->schedule = execlists_schedule;
+
+	engine->set_default_submission = execlists_set_default_submission;
 
 	engine->irq_enable = gen8_logical_ring_enable_irq;
 	engine->irq_disable = gen8_logical_ring_disable_irq;

drivers/gpu/drm/i915/intel_lrc.h

@@ -87,6 +87,5 @@ uint64_t intel_lr_context_descriptor(struct i915_gem_context *ctx,
 /* Execlists */
 int intel_sanitize_enable_execlists(struct drm_i915_private *dev_priv,
 				    int enable_execlists);
-void intel_execlists_enable_submission(struct drm_i915_private *dev_priv);
 
 #endif /* _INTEL_LRC_H_ */

drivers/gpu/drm/i915/intel_ringbuffer.c

@@ -2050,6 +2050,16 @@ static void intel_ring_init_irq(struct drm_i915_private *dev_priv,
 	}
 }
 
+static void i9xx_set_default_submission(struct intel_engine_cs *engine)
+{
+	engine->submit_request = i9xx_submit_request;
+}
+
+static void gen6_bsd_set_default_submission(struct intel_engine_cs *engine)
+{
+	engine->submit_request = gen6_bsd_submit_request;
+}
+
 static void intel_ring_default_vfuncs(struct drm_i915_private *dev_priv,
 				      struct intel_engine_cs *engine)
 {
@@ -2080,7 +2090,8 @@ static void intel_ring_default_vfuncs(struct drm_i915_private *dev_priv,
 				engine->emit_breadcrumb_sz++;
 		}
 	}
-	engine->submit_request = i9xx_submit_request;
+
+	engine->set_default_submission = i9xx_set_default_submission;
 
 	if (INTEL_GEN(dev_priv) >= 8)
 		engine->emit_bb_start = gen8_emit_bb_start;
@@ -2165,7 +2176,7 @@ int intel_init_bsd_ring_buffer(struct intel_engine_cs *engine)
 	if (INTEL_GEN(dev_priv) >= 6) {
 		/* gen6 bsd needs a special wa for tail updates */
 		if (IS_GEN6(dev_priv))
-			engine->submit_request = gen6_bsd_submit_request;
+			engine->set_default_submission = gen6_bsd_set_default_submission;
 		engine->emit_flush = gen6_bsd_ring_flush;
 		if (INTEL_GEN(dev_priv) < 8)
 			engine->irq_enable_mask = GT_BSD_USER_INTERRUPT;

drivers/gpu/drm/i915/intel_ringbuffer.h

@@ -273,6 +273,8 @@ struct intel_engine_cs {
 	void		(*reset_hw)(struct intel_engine_cs *engine,
 				    struct drm_i915_gem_request *req);
 
+	void		(*set_default_submission)(struct intel_engine_cs *engine);
+
 	int		(*context_pin)(struct intel_engine_cs *engine,
 				       struct i915_gem_context *ctx);
 	void		(*context_unpin)(struct intel_engine_cs *engine,
@@ -676,4 +678,6 @@ static inline u32 *gen8_emit_pipe_control(u32 *batch, u32 flags, u32 offset)
 bool intel_engine_is_idle(struct intel_engine_cs *engine);
 bool intel_engines_are_idle(struct drm_i915_private *dev_priv);
 
+void intel_engines_reset_default_submission(struct drm_i915_private *i915);
+
 #endif /* _INTEL_RINGBUFFER_H_ */