From eac4d44131325c1a11c7f3e520a675003500ac49 Mon Sep 17 00:00:00 2001
From: "Wesley W. Terpstra" <wesley@sifive.com>
Date: Tue, 30 Aug 2016 16:16:45 -0700
Subject: [PATCH] tilelink2: don't apply HintHandler to B=>C by default

---
 .../main/scala/tilelink2/HintHandler.scala    | 66 ++++++++++++-------
 1 file changed, 43 insertions(+), 23 deletions(-)

diff --git a/uncore/src/main/scala/tilelink2/HintHandler.scala b/uncore/src/main/scala/tilelink2/HintHandler.scala
index 53c2ca0b..e32df111 100644
--- a/uncore/src/main/scala/tilelink2/HintHandler.scala
+++ b/uncore/src/main/scala/tilelink2/HintHandler.scala
@@ -5,11 +5,11 @@ package uncore.tilelink2
 import Chisel._
 
 // Acks Hints for managers that don't support them or Acks all Hints if !passthrough
-class TLHintHandler(passthrough: Boolean = true) extends TLSimpleFactory
+class TLHintHandler(supportManagers: Boolean = true, supportClients: Boolean = false, passthrough: Boolean = true) extends TLSimpleFactory
 {
   val node = TLAdapterNode(
-    clientFn  = { case Seq(c) => c.copy(clients  = c.clients .map(_.copy(supportsHint = true))) },
-    managerFn = { case Seq(m) => m.copy(managers = m.managers.map(_.copy(supportsHint = true))) })
+    clientFn  = { case Seq(c) => if (supportClients)  c.copy(clients  = c.clients .map(_.copy(supportsHint = true))) else c },
+    managerFn = { case Seq(m) => if (supportManagers) m.copy(managers = m.managers.map(_.copy(supportsHint = true))) else m })
 
   lazy val module = Module(new TLModule(this) {
     val io = new Bundle {
@@ -22,29 +22,49 @@ class TLHintHandler(passthrough: Boolean = true) extends TLSimpleFactory
     val edgeIn  = node.edgesIn(0)
     val edgeOut = node.edgesOut(0)
 
-    val handleA = if (passthrough) !edgeOut.manager.supportsHint(in.a.bits.address) else Bool(true)
-    val bypassD = handleA && in.a.bits.opcode === TLMessages.Hint
+    if (supportManagers) {
+      val handleA = if (passthrough) !edgeOut.manager.supportsHint(in.a.bits.address) else Bool(true)
+      val bypassD = handleA && in.a.bits.opcode === TLMessages.Hint
 
-    // Prioritize existing D traffic over HintAck
-    in.d.valid  := out.d.valid || (bypassD && in.a.valid)
-    out.d.ready := in.d.ready
-    in.d.bits   := Mux(out.d.valid, out.d.bits, edgeIn.HintAck(in.a.bits.source, in.a.bits.size))
+      // Prioritize existing D traffic over HintAck
+      in.d.valid  := out.d.valid || (bypassD && in.a.valid)
+      out.d.ready := in.d.ready
+      in.d.bits   := Mux(out.d.valid, out.d.bits, edgeIn.HintAck(in.a.bits.source, in.a.bits.size))
 
-    in.a.ready  := Mux(bypassD, in.d.ready && !out.d.valid, out.a.ready)
-    out.a.valid := in.a.valid && !bypassD
-    out.a.bits  := in.a.bits
-    
-    val handleB = if (passthrough) !edgeIn.client.supportsHint(out.b.bits.source) else Bool(true)
-    val bypassC = handleB && out.b.bits.opcode === TLMessages.Hint
+      in.a.ready  := Mux(bypassD, in.d.ready && !out.d.valid, out.a.ready)
+      out.a.valid := in.a.valid && !bypassD
+      out.a.bits  := in.a.bits
+    } else {
+      out.a.valid := in.a.valid
+      in.a.ready := out.a.ready
+      out.a.bits := in.a.bits
 
-    // Prioritize existing C traffic over HintAck
-    out.c.valid := in.c.valid || (bypassC && in.b.valid)
-    in.c.ready  := out.c.ready
-    out.c.bits  := Mux(in.c.valid, in.c.bits, edgeOut.HintAck(out.b.bits.address, out.b.bits.size))
-    
-    out.b.ready := Mux(bypassC, out.c.ready && !in.c.valid, in.b.ready)
-    in.b.valid  := out.b.valid && !bypassC
-    in.b.bits   := out.b.bits
+      in.d.valid := out.d.valid
+      out.d.ready := in.d.ready
+      in.d.bits := out.d.bits
+    }
+
+    if (supportClients) {
+      val handleB = if (passthrough) !edgeIn.client.supportsHint(out.b.bits.source) else Bool(true)
+      val bypassC = handleB && out.b.bits.opcode === TLMessages.Hint
+
+      // Prioritize existing C traffic over HintAck
+      out.c.valid := in.c.valid || (bypassC && in.b.valid)
+      in.c.ready  := out.c.ready
+      out.c.bits  := Mux(in.c.valid, in.c.bits, edgeOut.HintAck(out.b.bits.address, out.b.bits.size))
+
+      out.b.ready := Mux(bypassC, out.c.ready && !in.c.valid, in.b.ready)
+      in.b.valid  := out.b.valid && !bypassC
+      in.b.bits   := out.b.bits
+    } else {
+      in.b.valid := out.b.valid
+      out.b.ready := in.b.ready
+      in.b.bits := out.b.bits
+
+      out.c.valid := in.c.valid
+      in.c.ready := out.c.ready
+      out.c.bits := in.c.bits
+    }
 
     // Pass E through unchanged
     out.e.valid := in.e.valid