drm/i915: Moved the for_each_ring loop outside of i915_gem_context_enable()

The start of day context initialisation code in i915_gem_context_enable() loops
over each ring and calls the legacy switch context or the execlist init context
code as appropriate.

This patch moves the ring looping out of that function in to the top level
caller i915_gem_init_hw(). This means the a single pass can be made over all
rings doing the PPGTT, L3 remap and context initialisation of each ring
altogether.

For: VIZ-5115
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Tomas Elf <tomas.elf@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_drv.h

@@ -3039,7 +3039,7 @@ int __must_check i915_gem_context_init(struct drm_device *dev);
 void i915_gem_context_fini(struct drm_device *dev);
 void i915_gem_context_reset(struct drm_device *dev);
 int i915_gem_context_open(struct drm_device *dev, struct drm_file *file);
-int i915_gem_context_enable(struct drm_i915_private *dev_priv);
+int i915_gem_context_enable(struct intel_engine_cs *ring);
 void i915_gem_context_close(struct drm_device *dev, struct drm_file *file);
 int i915_switch_context(struct intel_engine_cs *ring,
 			struct intel_context *to);

drivers/gpu/drm/i915/i915_gem.c

@@ -5052,6 +5052,8 @@ i915_gem_init_hw(struct drm_device *dev)
 	 */
 	init_unused_rings(dev);
 
+	BUG_ON(!dev_priv->ring[RCS].default_context);
+
 	ret = i915_ppgtt_init_hw(dev);
 	if (ret) {
 		DRM_ERROR("PPGTT enable HW failed %d\n", ret);
@@ -5067,6 +5069,8 @@ i915_gem_init_hw(struct drm_device *dev)
 
 	/* Now it is safe to go back round and do everything else: */
 	for_each_ring(ring, dev_priv, i) {
+		WARN_ON(!ring->default_context);
+
 		if (ring->id == RCS) {
 			for (j = 0; j < NUM_L3_SLICES(dev); j++)
 				i915_gem_l3_remap(ring, j);
@@ -5078,14 +5082,13 @@ i915_gem_init_hw(struct drm_device *dev)
 			i915_gem_cleanup_ringbuffer(dev);
 			goto out;
 		}
-	}
 
-	ret = i915_gem_context_enable(dev_priv);
-	if (ret && ret != -EIO) {
-		DRM_ERROR("Context enable failed %d\n", ret);
-		i915_gem_cleanup_ringbuffer(dev);
-
-		goto out;
+		ret = i915_gem_context_enable(ring);
+		if (ret && ret != -EIO) {
+			DRM_ERROR("Context enable ring #%d failed %d\n", i, ret);
+			i915_gem_cleanup_ringbuffer(dev);
+			goto out;
+		}
 	}
 
 out:

drivers/gpu/drm/i915/i915_gem_context.c

@@ -409,32 +409,22 @@ void i915_gem_context_fini(struct drm_device *dev)
 	i915_gem_context_unreference(dctx);
 }
 
-int i915_gem_context_enable(struct drm_i915_private *dev_priv)
+int i915_gem_context_enable(struct intel_engine_cs *ring)
 {
-	struct intel_engine_cs *ring;
-	int ret, i;
-
-	BUG_ON(!dev_priv->ring[RCS].default_context);
+	int ret;
 
 	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;
-				}
-			}
-		}
+		if (ring->init_context == NULL)
+			return 0;
 
+		ret = ring->init_context(ring, ring->default_context);
 	} else
-		for_each_ring(ring, dev_priv, i) {
-			ret = i915_switch_context(ring, ring->default_context);
-			if (ret)
-				return ret;
-		}
+		ret = i915_switch_context(ring, ring->default_context);
+
+	if (ret) {
+		DRM_ERROR("ring init context: %d\n", ret);
+		return ret;
+	}
 
 	return 0;
 }