drm/i915: Store a pointer to intel_context in i915_request

To ease the frequent and ugly pointer dance of
&request->gem_context->engine[request->engine->id] during request
submission, store that pointer as request->hw_context. One major
advantage that we will exploit later is that this decouples the logical
context state from the engine itself.

v2: Set mock_context->ops so we don't crash and burn in selftests.
    Cleanups from Tvrtko.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Acked-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180517212633.24934-3-chris@chris-wilson.co.uk

2 files changed, 34 insertions, 14 deletions

diff --git a/drivers/gpu/drm/i915/selftests/mock_context.c b/drivers/gpu/drm/i915/selftests/mock_context.c
index 501becc47c0c..8904f1ce64e3 100644
--- a/drivers/gpu/drm/i915/selftests/mock_context.c
+++ b/drivers/gpu/drm/i915/selftests/mock_context.c
@@ -30,6 +30,7 @@ mock_context(struct drm_i915_private *i915,
 	     const char *name)
 {
 	struct i915_gem_context *ctx;
+	unsigned int n;
 	int ret;
 
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
@@ -43,6 +44,12 @@ mock_context(struct drm_i915_private *i915,
 	INIT_RADIX_TREE(&ctx->handles_vma, GFP_KERNEL);
 	INIT_LIST_HEAD(&ctx->handles_list);
 
+	for (n = 0; n < ARRAY_SIZE(ctx->__engine); n++) {
+		struct intel_context *ce = &ctx->__engine[n];
+
+		ce->gem_context = ctx;
+	}
+
 	ret = ida_simple_get(&i915->contexts.hw_ida,
 			     0, MAX_CONTEXT_HW_ID, GFP_KERNEL);
 	if (ret < 0)
diff --git a/drivers/gpu/drm/i915/selftests/mock_engine.c b/drivers/gpu/drm/i915/selftests/mock_engine.c
index 26bf29d97007..33eddfc1f8ce 100644
--- a/drivers/gpu/drm/i915/selftests/mock_engine.c
+++ b/drivers/gpu/drm/i915/selftests/mock_engine.c
@@ -72,25 +72,37 @@ static void hw_delay_complete(struct timer_list *t)
 	spin_unlock(&engine->hw_lock);
 }
 
-static struct intel_ring *
-mock_context_pin(struct intel_engine_cs *engine,
-		 struct i915_gem_context *ctx)
+static void mock_context_unpin(struct intel_context *ce)
 {
-	struct intel_context *ce = to_intel_context(ctx, engine);
+	if (--ce->pin_count)
+		return;
 
-	if (!ce->pin_count++)
-		i915_gem_context_get(ctx);
+	i915_gem_context_put(ce->gem_context);
+}
 
-	return engine->buffer;
+static void mock_context_destroy(struct intel_context *ce)
+{
+	GEM_BUG_ON(ce->pin_count);
 }
 
-static void mock_context_unpin(struct intel_engine_cs *engine,
-			       struct i915_gem_context *ctx)
+static const struct intel_context_ops mock_context_ops = {
+	.unpin = mock_context_unpin,
+	.destroy = mock_context_destroy,
+};
+
+static struct intel_context *
+mock_context_pin(struct intel_engine_cs *engine,
+		 struct i915_gem_context *ctx)
 {
 	struct intel_context *ce = to_intel_context(ctx, engine);
 
-	if (!--ce->pin_count)
-		i915_gem_context_put(ctx);
+	if (!ce->pin_count++) {
+		i915_gem_context_get(ctx);
+		ce->ring = engine->buffer;
+		ce->ops = &mock_context_ops;
+	}
+
+	return ce;
 }
 
 static int mock_request_alloc(struct i915_request *request)
@@ -185,7 +197,6 @@ struct intel_engine_cs *mock_engine(struct drm_i915_private *i915,
 	engine->base.status_page.page_addr = (void *)(engine + 1);
 
 	engine->base.context_pin = mock_context_pin;
-	engine->base.context_unpin = mock_context_unpin;
 	engine->base.request_alloc = mock_request_alloc;
 	engine->base.emit_flush = mock_emit_flush;
 	engine->base.emit_breadcrumb = mock_emit_breadcrumb;
@@ -238,11 +249,13 @@ void mock_engine_free(struct intel_engine_cs *engine)
 {
 	struct mock_engine *mock =
 		container_of(engine, typeof(*mock), base);
+	struct intel_context *ce;
 
 	GEM_BUG_ON(timer_pending(&mock->hw_delay));
 
-	if (engine->last_retired_context)
-		intel_context_unpin(engine->last_retired_context, engine);
+	ce = fetch_and_zero(&engine->last_retired_context);
+	if (ce)
+		intel_context_unpin(ce);
 
 	mock_ring_free(engine->buffer);