From 65005c0dc0612a7ede6bab497393bd023c4b3592 Mon Sep 17 00:00:00 2001
From: Geoffrey McRae <geoff@hostfission.com>
Date: Tue, 2 Jun 2026 19:17:27 +1000
Subject: [PATCH] [idd] all: add default refresh rate setting support

---
 idd/LGCommon/PipeMsg.h               |  1 +
 idd/LGIdd/CIndirectDeviceContext.cpp |  4 ++--
 idd/LGIdd/CPipeServer.cpp            | 11 ++++++-----
 idd/LGIdd/CPipeServer.h              |  2 +-
 idd/LGIdd/CSettings.cpp              | 20 ++++++++++++++++++++
 idd/LGIdd/CSettings.h                |  1 +
 idd/LGIddHelper/CPipeClient.cpp      |  9 +++++----
 7 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/idd/LGCommon/PipeMsg.h b/idd/LGCommon/PipeMsg.h
index 17b7712c..cf74d6fe 100644
--- a/idd/LGCommon/PipeMsg.h
+++ b/idd/LGCommon/PipeMsg.h
@@ -46,6 +46,7 @@ struct LGPipeMsg
     {
       uint32_t width;
       uint32_t height;
+      uint32_t refresh;
     }
     displayMode;
   };
diff --git a/idd/LGIdd/CIndirectDeviceContext.cpp b/idd/LGIdd/CIndirectDeviceContext.cpp
index 7cd61ccb..9c28a7c5 100644
--- a/idd/LGIdd/CIndirectDeviceContext.cpp
+++ b/idd/LGIdd/CIndirectDeviceContext.cpp
@@ -202,7 +202,7 @@ void CIndirectDeviceContext::OnAssignSwapChain()
   if (m_doSetMode)
   {
     m_doSetMode = false;
-    g_pipe.SetDisplayMode(m_setMode.width, m_setMode.height); //FIXME: refresh
+    g_pipe.SetDisplayMode(m_setMode.width, m_setMode.height, m_setMode.refresh);
   }
 }
 
@@ -300,7 +300,7 @@ void CIndirectDeviceContext::SetResolution(int width, int height)
 {
   m_setMode.width     = width;
   m_setMode.height    = height;
-  m_setMode.refresh   = 120; //FIXME
+  m_setMode.refresh   = g_settings.GetDefaultRefresh();
   m_setMode.preferred = true;
   g_settings.SetExtraMode(m_setMode);
 
diff --git a/idd/LGIdd/CPipeServer.cpp b/idd/LGIdd/CPipeServer.cpp
index 0e8eb6d4..e71ad500 100644
--- a/idd/LGIdd/CPipeServer.cpp
+++ b/idd/LGIdd/CPipeServer.cpp
@@ -162,15 +162,16 @@ void CPipeServer::SetCursorPos(uint32_t x, uint32_t y)
   WriteMsg(msg);
 }
 
-void CPipeServer::SetDisplayMode(uint32_t width, uint32_t height)
+void CPipeServer::SetDisplayMode(uint32_t width, uint32_t height, uint32_t refresh)
 {
   if (!m_connected)
     return;
 
   LGPipeMsg msg;
-  msg.size               = sizeof(msg);
-  msg.type               = LGPipeMsg::SETDISPLAYMODE;
-  msg.displayMode.width  = width;
-  msg.displayMode.height = height;
+  msg.size                = sizeof(msg);
+  msg.type                = LGPipeMsg::SETDISPLAYMODE;
+  msg.displayMode.width   = width;
+  msg.displayMode.height  = height;
+  msg.displayMode.refresh = refresh;
   WriteMsg(msg);
 }
\ No newline at end of file
diff --git a/idd/LGIdd/CPipeServer.h b/idd/LGIdd/CPipeServer.h
index 84896a14..f2fe5a63 100644
--- a/idd/LGIdd/CPipeServer.h
+++ b/idd/LGIdd/CPipeServer.h
@@ -54,7 +54,7 @@ class CPipeServer
     void DeInit();
 
     void SetCursorPos(uint32_t x, uint32_t y);
-    void SetDisplayMode(uint32_t width, uint32_t height);
+    void SetDisplayMode(uint32_t width, uint32_t height, uint32_t refresh);
 };
 
 extern CPipeServer g_pipe;
\ No newline at end of file
diff --git a/idd/LGIdd/CSettings.cpp b/idd/LGIdd/CSettings.cpp
index 6f806341..da7934c1 100644
--- a/idd/LGIdd/CSettings.cpp
+++ b/idd/LGIdd/CSettings.cpp
@@ -166,6 +166,26 @@ bool CSettings::GetExtraMode(DisplayMode& mode)
   return ParseModeString(extraMode, mode);
 }
 
+unsigned CSettings::GetDefaultRefresh() const
+{
+  DWORD refresh = 60;
+  DWORD cb      = sizeof(refresh);
+  HKEY  hKey    = nullptr;
+
+  LONG st = RegOpenKeyExW(HKEY_LOCAL_MACHINE, LGIDD_REGKEY, 0, KEY_QUERY_VALUE, &hKey);
+  if (st == ERROR_SUCCESS)
+  {
+    DWORD type = 0;
+    st = RegGetValueW(hKey, nullptr, L"DefaultRefresh", RRF_RT_REG_DWORD, &type, &refresh, &cb);
+    RegCloseKey(hKey);
+  }
+
+  if (st != ERROR_SUCCESS || refresh < 30 || refresh > 1000)
+    return 60;
+
+  return refresh;
+}
+
 bool CSettings::ReadModesValue(std::vector<std::wstring> &out) const
 {
   HKEY hKey = nullptr;
diff --git a/idd/LGIdd/CSettings.h b/idd/LGIdd/CSettings.h
index b0bf186d..055e8a74 100644
--- a/idd/LGIdd/CSettings.h
+++ b/idd/LGIdd/CSettings.h
@@ -41,6 +41,7 @@ class CSettings
     const DisplayModes& GetDisplayModes() { return m_displayModes; }
     void SetExtraMode(const DisplayMode & mode);
     bool GetExtraMode(DisplayMode & mode);
+    unsigned GetDefaultRefresh() const;
 
   private:
     DisplayModes m_displayModes;
diff --git a/idd/LGIddHelper/CPipeClient.cpp b/idd/LGIddHelper/CPipeClient.cpp
index f3de02ee..2108f029 100644
--- a/idd/LGIddHelper/CPipeClient.cpp
+++ b/idd/LGIddHelper/CPipeClient.cpp
@@ -290,10 +290,11 @@ void CPipeClient::HandleSetCursorPos(const LGPipeMsg& msg)
 void CPipeClient::HandleSetDisplayMode(const LGPipeMsg& msg)
 {
   DEVMODE dm = {};
-  dm.dmSize       = sizeof(dm);
-  dm.dmPelsWidth  = msg.displayMode.width;
-  dm.dmPelsHeight = msg.displayMode.height;
-  dm.dmFields     = DM_PELSWIDTH | DM_PELSHEIGHT;
+  dm.dmSize             = sizeof(dm);
+  dm.dmPelsWidth        = msg.displayMode.width;
+  dm.dmPelsHeight       = msg.displayMode.height;
+  dm.dmDisplayFrequency = msg.displayMode.refresh;
+  dm.dmFields           = DM_PELSWIDTH | DM_PELSHEIGHT | DM_DISPLAYFREQUENCY;
 
   LONG result = ChangeDisplaySettingsEx(NULL, &dm, NULL, CDS_UPDATEREGISTRY, NULL);
   if (result != DISP_CHANGE_SUCCESSFUL)