From 54b73aef5784f971c69143528108ebfc5516e314 Mon Sep 17 00:00:00 2001
From: "Wesley W. Terpstra" <wesley@sifive.com>
Date: Wed, 12 Oct 2016 21:11:32 -0700
Subject: [PATCH] tilelink2: WidthWidget and Fragmenter no longer erase latency

---
 src/main/scala/uncore/tilelink2/Buffer.scala      | 6 +++---
 src/main/scala/uncore/tilelink2/Fragmenter.scala  | 3 +--
 src/main/scala/uncore/tilelink2/WidthWidget.scala | 5 ++---
 3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/src/main/scala/uncore/tilelink2/Buffer.scala b/src/main/scala/uncore/tilelink2/Buffer.scala
index 659cf6dd..3ca2dec0 100644
--- a/src/main/scala/uncore/tilelink2/Buffer.scala
+++ b/src/main/scala/uncore/tilelink2/Buffer.scala
@@ -5,7 +5,7 @@ package uncore.tilelink2
 import Chisel._
 import chisel3.internal.sourceinfo.SourceInfo
 import diplomacy._
-import scala.math.max
+import scala.math.{min,max}
 
 // pipe is only used if a queue has depth = 1
 class TLBuffer(a: Int = 2, b: Int = 2, c: Int = 2, d: Int = 2, e: Int = 2, pipe: Boolean = true) extends LazyModule
@@ -17,8 +17,8 @@ class TLBuffer(a: Int = 2, b: Int = 2, c: Int = 2, d: Int = 2, e: Int = 2, pipe:
   require (e >= 0)
 
   val node = TLAdapterNode(
-    clientFn  = { seq => seq(0).copy(minLatency = seq(0).minLatency + max(1,b) + max(1,c)) },
-    managerFn = { seq => seq(0).copy(minLatency = seq(0).minLatency + max(1,a) + max(1,d)) })
+    clientFn  = { seq => seq(0).copy(minLatency = seq(0).minLatency + min(1,b) + min(1,c)) },
+    managerFn = { seq => seq(0).copy(minLatency = seq(0).minLatency + min(1,a) + min(1,d)) })
 
   lazy val module = new LazyModuleImp(this) {
     val io = new Bundle {
diff --git a/src/main/scala/uncore/tilelink2/Fragmenter.scala b/src/main/scala/uncore/tilelink2/Fragmenter.scala
index a98321b1..10df7da8 100644
--- a/src/main/scala/uncore/tilelink2/Fragmenter.scala
+++ b/src/main/scala/uncore/tilelink2/Fragmenter.scala
@@ -39,10 +39,9 @@ class TLFragmenter(minSize: Int, maxSize: Int, alwaysMin: Boolean = false) exten
   def mapClient(c: TLClientParameters) = c.copy(
     sourceId = IdRange(c.sourceId.start << fragmentBits, c.sourceId.end << fragmentBits))
 
-  // Because the Fragmenter stalls inner A while serving outer, it can wipe away inner latency
   val node = TLAdapterNode(
     clientFn  = { case Seq(c) => c.copy(clients = c.clients.map(mapClient)) },
-    managerFn = { case Seq(m) => m.copy(managers = m.managers.map(mapManager), minLatency = 0) })
+    managerFn = { case Seq(m) => m.copy(managers = m.managers.map(mapManager)) })
 
   lazy val module = new LazyModuleImp(this) {
     val io = new Bundle {
diff --git a/src/main/scala/uncore/tilelink2/WidthWidget.scala b/src/main/scala/uncore/tilelink2/WidthWidget.scala
index 32dc793b..bfbf9eb4 100644
--- a/src/main/scala/uncore/tilelink2/WidthWidget.scala
+++ b/src/main/scala/uncore/tilelink2/WidthWidget.scala
@@ -10,10 +10,9 @@ import scala.math.{min,max}
 // innBeatBytes => the new client-facing bus width
 class TLWidthWidget(innerBeatBytes: Int) extends LazyModule
 {
-  // Because we stall the request while sending beats, atomics can overlap => minLatency=0
   val node = TLAdapterNode(
-    clientFn  = { case Seq(c) => c.copy(minLatency = 0) },
-    managerFn = { case Seq(m) => m.copy(minLatency = 0, beatBytes = innerBeatBytes) })
+    clientFn  = { case Seq(c) => c },
+    managerFn = { case Seq(m) => m.copy(beatBytes = innerBeatBytes) })
 
   lazy val module = new LazyModuleImp(this) {
     val io = new Bundle {