drm/i915: Split execlists hardware status page initialisation from setup

Split the hardware status page into setup and initialisation,
where setup means setting up the driver state to support the
engine, and initialization means programming the hardware
with the before set up state.

This way the design matches the design of the engine setup/init
code which is split in the same fashion and it enables the
stages to be used in a balanced fashion (engine setup - hws
setup, engine init - hws init).

This will enable the upcoming improvements to slot in without
any kludges on the GPU reset path.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_lrc.c

@@ -229,9 +229,6 @@ enum {
 
 static int intel_lr_context_pin(struct intel_context *ctx,
 				struct intel_engine_cs *engine);
-static void lrc_setup_hardware_status_page(struct intel_engine_cs *engine,
-					   struct drm_i915_gem_object *default_ctx_obj);
-
 
 /**
  * intel_sanitize_enable_execlists() - sanitize i915.enable_execlists
@@ -1580,14 +1577,22 @@ out:
 	return ret;
 }
 
+static void lrc_init_hws(struct intel_engine_cs *engine)
+{
+	struct drm_i915_private *dev_priv = engine->dev->dev_private;
+
+	I915_WRITE(RING_HWS_PGA(engine->mmio_base),
+		   (u32)engine->status_page.gfx_addr);
+	POSTING_READ(RING_HWS_PGA(engine->mmio_base));
+}
+
 static int gen8_init_common_ring(struct intel_engine_cs *engine)
 {
 	struct drm_device *dev = engine->dev;
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	unsigned int next_context_status_buffer_hw;
 
-	lrc_setup_hardware_status_page(engine,
-				       dev_priv->kernel_context->engine[engine->id].state);
+	lrc_init_hws(engine);
 
 	I915_WRITE_IMR(engine,
 		       ~(engine->irq_enable_mask | engine->irq_keep_mask));
@@ -2087,6 +2092,20 @@ logical_ring_default_irqs(struct intel_engine_cs *engine, unsigned shift)
 	engine->irq_keep_mask = GT_CONTEXT_SWITCH_INTERRUPT << shift;
 }
 
+static void
+lrc_setup_hws(struct intel_engine_cs *engine,
+	      struct drm_i915_gem_object *dctx_obj)
+{
+	struct page *page;
+
+	/* The HWSP is part of the default context object in LRC mode. */
+	engine->status_page.gfx_addr = i915_gem_obj_ggtt_offset(dctx_obj) +
+				       LRC_PPHWSP_PN * PAGE_SIZE;
+	page = i915_gem_object_get_page(dctx_obj, LRC_PPHWSP_PN);
+	engine->status_page.page_addr = kmap(page);
+	engine->status_page.obj = dctx_obj;
+}
+
 static int
 logical_ring_init(struct drm_device *dev, struct intel_engine_cs *engine)
 {
@@ -2145,6 +2164,9 @@ logical_ring_init(struct drm_device *dev, struct intel_engine_cs *engine)
 		goto error;
 	}
 
+	/* And setup the hardware status page. */
+	lrc_setup_hws(engine, dctx->engine[engine->id].state);
+
 	return 0;
 
 error:
@@ -2605,24 +2627,6 @@ uint32_t intel_lr_context_size(struct intel_engine_cs *engine)
 	return ret;
 }
 
-static void lrc_setup_hardware_status_page(struct intel_engine_cs *engine,
-					   struct drm_i915_gem_object *default_ctx_obj)
-{
-	struct drm_i915_private *dev_priv = engine->dev->dev_private;
-	struct page *page;
-
-	/* The HWSP is part of the default context object in LRC mode. */
-	engine->status_page.gfx_addr = i915_gem_obj_ggtt_offset(default_ctx_obj)
-			+ LRC_PPHWSP_PN * PAGE_SIZE;
-	page = i915_gem_object_get_page(default_ctx_obj, LRC_PPHWSP_PN);
-	engine->status_page.page_addr = kmap(page);
-	engine->status_page.obj = default_ctx_obj;
-
-	I915_WRITE(RING_HWS_PGA(engine->mmio_base),
-			(u32)engine->status_page.gfx_addr);
-	POSTING_READ(RING_HWS_PGA(engine->mmio_base));
-}
-
 /**
  * intel_lr_context_deferred_alloc() - create the LRC specific bits of a context
  * @ctx: LR context to create.