drm/i915: Fix startup failure in LRC mode after recent init changes

A previous commit introduced engine init changes:

    commit 372ee59699d9 ("drm/i915: Only init engines once")

This broke execlists as intel_lr_context_render_state_init was trying to emit
commands to the RCS for the default context before the ring->init_hw was called.

Made a new gen8_init_rcs_context function and assign in to render ring
init_context.  Moved call to intel_logical_ring_workarounds_emit into
gen8_init_rcs_context to maintain previous functionality.

Moved call to render_state_init from lr_context_deferred_create into
gen8_init_rcs_context, and modified deferred_create to call ring->init_context
for non-default contexts.

Modified i915_gem_context_enable to call ring->init_context for the default
context.

So init_context will now always be called when the hw is ready - in
i915_gem_context_enable for the default context and in lr_context_deferred_create
for other contexts.
Signed-off-by: Thomas Daniel <thomas.daniel@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem_context.c

@@ -408,14 +408,25 @@ int i915_gem_context_enable(struct drm_i915_private *dev_priv)
 
 	BUG_ON(!dev_priv->ring[RCS].default_context);
 
-	if (i915.enable_execlists)
-		return 0;
+	if (i915.enable_execlists) {
+		for_each_ring(ring, dev_priv, i) {
+			if (ring->init_context) {
+				ret = ring->init_context(ring,
+						ring->default_context);
+				if (ret) {
+					DRM_ERROR("ring init context: %d\n",
+							ret);
+					return ret;
+				}
+			}
+		}
 
-	for_each_ring(ring, dev_priv, i) {
-		ret = i915_switch_context(ring, ring->default_context);
-		if (ret)
-			return ret;
-	}
+	} else
+		for_each_ring(ring, dev_priv, i) {
+			ret = i915_switch_context(ring, ring->default_context);
+			if (ret)
+				return ret;
+		}
 
 	return 0;
 }

drivers/gpu/drm/i915/intel_lrc.c

@@ -1336,6 +1336,18 @@ static int gen8_emit_request(struct intel_ringbuffer *ringbuf)
 	return 0;
 }
 
+static int gen8_init_rcs_context(struct intel_engine_cs *ring,
+		       struct intel_context *ctx)
+{
+	int ret;
+
+	ret = intel_logical_ring_workarounds_emit(ring, ctx);
+	if (ret)
+		return ret;
+
+	return intel_lr_context_render_state_init(ring, ctx);
+}
+
 /**
  * intel_logical_ring_cleanup() - deallocate the Engine Command Streamer
  *
@@ -1409,7 +1421,7 @@ static int logical_render_ring_init(struct drm_device *dev)
 		ring->irq_keep_mask |= GT_RENDER_L3_PARITY_ERROR_INTERRUPT;
 
 	ring->init_hw = gen8_init_render_ring;
-	ring->init_context = intel_logical_ring_workarounds_emit;
+	ring->init_context = gen8_init_rcs_context;
 	ring->cleanup = intel_fini_pipe_control;
 	ring->get_seqno = gen8_get_seqno;
 	ring->set_seqno = gen8_set_seqno;
@@ -1904,21 +1916,17 @@ int intel_lr_context_deferred_create(struct intel_context *ctx,
 
 	if (ctx == ring->default_context)
 		lrc_setup_hardware_status_page(ring, ctx_obj);
-
-	if (ring->id == RCS && !ctx->rcs_initialized) {
+	else if (ring->id == RCS && !ctx->rcs_initialized) {
 		if (ring->init_context) {
 			ret = ring->init_context(ring, ctx);
-			if (ret)
+			if (ret) {
 				DRM_ERROR("ring init context: %d\n", ret);
+				ctx->engine[ring->id].ringbuf = NULL;
+				ctx->engine[ring->id].state = NULL;
+				goto error;
+			}
 		}
 
-		ret = intel_lr_context_render_state_init(ring, ctx);
-		if (ret) {
-			DRM_ERROR("Init render state failed: %d\n", ret);
-			ctx->engine[ring->id].ringbuf = NULL;
-			ctx->engine[ring->id].state = NULL;
-			goto error;
-		}
 		ctx->rcs_initialized = true;
 	}