From afc38abe082e69ed2e88e50b1c686ef05e4a7f03 Mon Sep 17 00:00:00 2001
From: bbracker <bbracker@hmc.edu>
Date: Thu, 21 Apr 2022 10:31:16 -0700
Subject: [PATCH] change how tristate I/O is spoofed in GPIO loopback test

---
 pipelined/src/uncore/gpio.sv | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pipelined/src/uncore/gpio.sv b/pipelined/src/uncore/gpio.sv
index ad82e62aa..a70b44db4 100644
--- a/pipelined/src/uncore/gpio.sv
+++ b/pipelined/src/uncore/gpio.sv
@@ -146,8 +146,8 @@ module gpio (
 
   // chip i/o
   // connect OUT to IN for loopback testing
-  if (`GPIO_LOOPBACK_TEST) assign input0d = GPIOPinsOut & output_en | (GPIOPinsIn  & input_en);
-  else                     assign input0d = GPIOPinsIn  & input_en;
+  if (`GPIO_LOOPBACK_TEST) assign input0d = ((output_en & GPIOPinsOut) | (~output_en & GPIOPinsIn)) & input_en;
+  else                     assign input0d = GPIOPinsIn & input_en;
   flop #(32) sync1(HCLK,input0d,input1d);
   flop #(32) sync2(HCLK,input1d,input2d);
   flop #(32) sync3(HCLK,input2d,input3d);