Check the serial buffer empty status before performing the serial IO reading operation.

Signed-off-by: niruiyu
Reviewed-by: vanjeff
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12581 6f19259b-4bc3-4df7-8a09-765794883524

diff --git a/MdeModulePkg/Universal/Console/TerminalDxe/TerminalConIn.c b/MdeModulePkg/Universal/Console/TerminalDxe/TerminalConIn.c
index 47881a9d9c70db7750136cd6bb38b8e8cd4219eb..90bac164bce2a01e3a8e13a193ff4d83f81192a4 100644 (file)
--- a/MdeModulePkg/Universal/Console/TerminalDxe/TerminalConIn.c
+++ b/MdeModulePkg/Universal/Console/TerminalDxe/TerminalConIn.c
@@ -515,6 +515,7 @@ TerminalConInTimerHandler (
 {\r
   EFI_STATUS              Status;\r
   TERMINAL_DEV            *TerminalDevice;\r
+  UINT32                  Control;\r
   UINT8                   Input;\r
   EFI_SERIAL_IO_MODE      *Mode;\r
   EFI_SERIAL_IO_PROTOCOL  *SerialIo;\r
@@ -558,27 +559,33 @@ TerminalConInTimerHandler (
       TerminalDevice->SerialInTimeOut = SerialInTimeOut;\r
     }\r
   }\r
-\r
   //\r
-  // Fetch all the keys in the serial buffer,\r
-  // and insert the byte stream into RawFIFO.\r
+  // Check whether serial buffer is empty.\r
   //\r
-  while (!IsRawFiFoFull (TerminalDevice)) {\r
+  Status = SerialIo->GetControl (SerialIo, &Control);\r
 \r
-    Status = GetOneKeyFromSerial (TerminalDevice->SerialIo, &Input);\r
+  if ((Control & EFI_SERIAL_INPUT_BUFFER_EMPTY) == 0) {\r
+    //\r
+    // Fetch all the keys in the serial buffer,\r
+    // and insert the byte stream into RawFIFO.\r
+    //\r
+    while (!IsRawFiFoFull (TerminalDevice)) {\r
 \r
-    if (EFI_ERROR (Status)) {\r
-      if (Status == EFI_DEVICE_ERROR) {\r
-        REPORT_STATUS_CODE_WITH_DEVICE_PATH (\r
-          EFI_ERROR_CODE | EFI_ERROR_MINOR,\r
-          (EFI_PERIPHERAL_REMOTE_CONSOLE | EFI_P_EC_INPUT_ERROR),\r
-          TerminalDevice->DevicePath\r
-          );\r
+      Status = GetOneKeyFromSerial (TerminalDevice->SerialIo, &Input);\r
+\r
+      if (EFI_ERROR (Status)) {\r
+        if (Status == EFI_DEVICE_ERROR) {\r
+          REPORT_STATUS_CODE_WITH_DEVICE_PATH (\r
+            EFI_ERROR_CODE | EFI_ERROR_MINOR,\r
+            (EFI_PERIPHERAL_REMOTE_CONSOLE | EFI_P_EC_INPUT_ERROR),\r
+            TerminalDevice->DevicePath\r
+            );\r
+        }\r
+        break;\r
       }\r
-      break;\r
-    }\r
 \r
-    RawFiFoInsertOneKey (TerminalDevice, Input);\r
+      RawFiFoInsertOneKey (TerminalDevice, Input);\r
+    }\r
   }\r
 \r
   //\r