use variable vals, check existing vals first

Fix-GPUTimeoutDetectionResponse.ps1

@@ -1,5 +1,30 @@
-#[Microsoft.Win32.Registry]::SetValue('HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers','TdrLevel',3,[Microsoft.Win32.RegistryValueKind]::DWord)
+# Exit script if required variables are not defined
+If ( !$TdrLevel ) { Write-Error "TdrLevel must be defined, this script will now exit." ; Exit }
+If ( !$TdrDelay ) { Write-Error "TdrDelay must be defined, this script will now exit." ; Exit }
 
-# Setting TDR timeout to 64 seconds instead of the default 2 seconds
-Write-Output "Setting TDR timeout value to 64 seconds"
-[Microsoft.Win32.Registry]::SetValue('HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers','TdrDelay',64,[Microsoft.Win32.RegistryValueKind]::DWord)
+# Set the root registry path
+$RegPath = 'HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\GraphicsDrivers'
+
+# Get/set the TDR level
+$ExistingTdrLevel = [Microsoft.Win32.Registry]::GetValue($RegPath,'TdrLevel',3)
+If ( $TdrLevel -ne $ExistingTdrLevel ) {
+    # Set the TDR level
+    #   Note: 1 = Disable, 3 = Recover (default)
+    Write-Output "Existing TDR level:    ${ExistingTdrLevel}"
+    Write-Output "Changing TDR level to: ${TdrLevel}"
+    [Microsoft.Win32.Registry]::SetValue($RegPath,'TdrLevel',$TdrLevel,[Microsoft.Win32.RegistryValueKind]::DWord)
+} Else {
+    Write-Output "TDR value is already set to ${TdrLevel}"
+}
+
+# Get/set the TDR delay
+$ExistingTdrValue = [Microsoft.Win32.Registry]::GetValue($RegPath,'TdrDelay',2)
+If ( $TdrDelay -ne $ExistingTdrValue ) {
+    # Setting TDR timeout to $TdrDelay seconds
+    #   Note: 2 = Default
+    Write-Output "Existing TDR value:    ${ExistingTdrValue}"
+    Write-Output "Changing TDR value to: ${TdrDelay}"
+    [Microsoft.Win32.Registry]::SetValue($RegPath,'TdrDelay',$TdrDelay,[Microsoft.Win32.RegistryValueKind]::DWord)
+} Else {
+    Write-Output "TDR delay is already set to ${TdrDelay}"
+}