From 807b60988d23867e6edb879e4348f113563a624a Mon Sep 17 00:00:00 2001
From: Xavier Arteaga <xavier@softwareradiosystems.com>
Date: Fri, 28 May 2021 17:28:34 +0200
Subject: [PATCH] Wait for PHY workers to transmit before considering SYNC in
 IDLE

---
 srsue/hdr/phy/sync_state.h | 26 ++++++++++++++++++++++++++
 srsue/src/phy/sync.cc      | 26 ++++++++++----------------
 2 files changed, 36 insertions(+), 16 deletions(-)

diff --git a/srsue/hdr/phy/sync_state.h b/srsue/hdr/phy/sync_state.h
index af9d7c0c3..9e7715026 100644
--- a/srsue/hdr/phy/sync_state.h
+++ b/srsue/hdr/phy/sync_state.h
@@ -87,6 +87,32 @@ public:
   /* Helpers below this */
   bool is_idle() { return cur_state == IDLE; }
   bool is_camping() { return cur_state == CAMPING; }
+  bool wait_idle(uint32_t timeout_ms)
+  {
+    std::unique_lock<std::mutex> lock(outside);
+
+    // Avoid wasting time if the next state will not be IDLE
+    if (next_state != IDLE) {
+      return false;
+    }
+
+    // Calculate timeout
+    std::chrono::system_clock::time_point expire_time = std::chrono::system_clock::now();
+    expire_time += std::chrono::milliseconds(timeout_ms);
+
+    // Wait until the state is IDLE
+    while (cur_state != IDLE) {
+      std::cv_status cv_status = cvar.wait_until(lock, expire_time);
+
+      // Returns false if it timeouts
+      if (cv_status != std::cv_status::timeout) {
+        return false;
+      }
+    }
+
+    // Return true if the state is IDLE
+    return true;
+  }
 
   const char* to_string()
   {
diff --git a/srsue/src/phy/sync.cc b/srsue/src/phy/sync.cc
index 603e8b9cc..567e27ea4 100644
--- a/srsue/src/phy/sync.cc
+++ b/srsue/src/phy/sync.cc
@@ -220,17 +220,14 @@ rrc_interface_phy_lte::cell_search_ret_t sync::cell_search_start(phy_cell_t* fou
   rrc_proc_state = PROC_SEARCH_RUNNING;
 
   // Wait for SYNC thread to transition to IDLE (max. 2000ms)
-  uint32_t cnt = 0;
-  while (!phy_state.is_idle() && cnt <= 4000) {
-    Info("Cell Search: PHY state is_idle=%d, cnt=%d", phy_state.is_idle(), cnt);
-    usleep(500);
-    cnt++;
-  }
-  if (!phy_state.is_idle()) {
-    Error("Can not change Cell while not in IDLE");
+  if (not phy_state.wait_idle(2)) {
+    Error("SYNC: Can not search while not in IDLE");
     return ret;
   }
 
+  // Wait for workers to finish PHY processing
+  worker_com->semaphore.wait_all();
+
   // Reset worker once SYNC is IDLE to flush any worker states such as ACKs and pending grants
   worker_com->reset();
 
@@ -798,20 +795,17 @@ void sync::set_ue_sync_opts(srsran_ue_sync_t* q, float cfo)
 bool sync::set_cell(float cfo)
 {
   // Wait for SYNC thread to transition to IDLE (max. 2000ms)
-  uint32_t cnt = 0;
-  while (!phy_state.is_idle() && cnt <= 4000) {
-    Info("SYNC: PHY state is_idle=%d, cnt=%d", phy_state.is_idle(), cnt);
-    usleep(500);
-    cnt++;
-  }
-  if (!phy_state.is_idle()) {
-    Error("Can not change Cell while not in IDLE");
+  if (not phy_state.wait_idle(2)) {
+    Error("SYNC: Can not change Cell while not in IDLE");
     return false;
   }
 
   // Reset UE sync. Attention: doing this reset when the FSM is NOT IDLE can cause PSS/SSS out-of-sync
   srsran_ue_sync_reset(&ue_sync);
 
+  // Wait for workers to finish PHY processing
+  worker_com->semaphore.wait_all();
+
   // Reset worker once SYNC is IDLE to flush any worker states such as ACKs and pending grants
   worker_com->reset();