drm/i915: Consolidate L3 remapping LRI

We can use a single MI_LOAD_REGISTER_IMM command packet to write all the
L3 remapping registers, shrinking the number of bytes required to emit
the context switch.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461833819-3991-9-git-send-email-chris@chris-wilson.co.uk

drivers/gpu/drm/i915/i915_gem_context.c

@@ -603,16 +603,14 @@ mi_set_context(struct drm_i915_gem_request *req, u32 hw_flags)
 
 int i915_gem_l3_remap(struct drm_i915_gem_request *req, int slice)
 {
+	u32 *remap_info = req->i915->l3_parity.remap_info[slice];
 	struct intel_engine_cs *engine = req->engine;
-	struct drm_device *dev = engine->dev;
-	struct drm_i915_private *dev_priv = dev->dev_private;
-	u32 *remap_info = dev_priv->l3_parity.remap_info[slice];
 	int i, ret;
 
-	if (!HAS_L3_DPF(dev) || !remap_info)
+	if (!remap_info)
 		return 0;
 
-	ret = intel_ring_begin(req, GEN7_L3LOG_SIZE / 4 * 3);
+	ret = intel_ring_begin(req, GEN7_L3LOG_SIZE/4 * 2 + 2);
 	if (ret)
 		return ret;
 
@@ -621,15 +619,15 @@ int i915_gem_l3_remap(struct drm_i915_gem_request *req, int slice)
 	 * here because no other code should access these registers other than
 	 * at initialization time.
 	 */
-	for (i = 0; i < GEN7_L3LOG_SIZE / 4; i++) {
-		intel_ring_emit(engine, MI_LOAD_REGISTER_IMM(1));
+	intel_ring_emit(engine, MI_LOAD_REGISTER_IMM(GEN7_L3LOG_SIZE/4));
+	for (i = 0; i < GEN7_L3LOG_SIZE/4; i++) {
 		intel_ring_emit_reg(engine, GEN7_L3LOG(slice, i));
 		intel_ring_emit(engine, remap_info[i]);
 	}
-
+	intel_ring_emit(engine, MI_NOOP);
 	intel_ring_advance(engine);
 
-	return ret;
+	return 0;
 }
 
 static inline bool skip_rcs_switch(struct intel_engine_cs *engine,