[PATCH v1] ShellPkg/TftpDynamicCommand: Clarify the retry count option in command.

[Jiaxin Wu <Jiaxin.wu@intel.com>]

[-c <retry count>] is to define the number of times to transmit request
packets and wait for a response. The default value is 6. But it doesn't
specify the behavior of zero value. Here, The patch is to clear that:
Set to zero also means to use the default value.

Cc: Carsey Jaben <jaben.carsey@intel.com>
Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Wu Jiaxin <jiaxin.wu@intel.com>
---
 ShellPkg/DynamicCommand/TftpDynamicCommand/Tftp.c   | 6 +++++-
 ShellPkg/DynamicCommand/TftpDynamicCommand/Tftp.uni | 3 ++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/ShellPkg/DynamicCommand/TftpDynamicCommand/Tftp.c b/ShellPkg/DynamicCommand/TftpDynamicCommand/Tftp.c
index ac2813efc3..028686e1ff 100644
--- a/ShellPkg/DynamicCommand/TftpDynamicCommand/Tftp.c
+++ b/ShellPkg/DynamicCommand/TftpDynamicCommand/Tftp.c
@@ -216,11 +216,11 @@ EFI_MTFTP4_CONFIG_DATA DefaultMtftp4ConfigData = {
   { { 0, 0, 0, 0 } },               // SubnetMask        - Not relevant as UseDefaultSetting=TRUE
   0,                                // LocalPort         - Automatically assigned port number.
   { { 0, 0, 0, 0 } },               // GatewayIp         - Not relevant as UseDefaultSetting=TRUE
   { { 0, 0, 0, 0 } },               // ServerIp          - Not known yet
   69,                               // InitialServerPort - Standard TFTP server port
-  6,                                // TryCount          - Max number of retransmissions.
+  6,                                // TryCount          - The number of times to transmit request packets and wait for a response.
   4                                 // TimeoutValue      - Retransmission timeout in seconds.
 };
 
 STATIC CONST SHELL_PARAM_ITEM ParamList[] = {
   {L"-i", TypeValue},
@@ -419,10 +419,14 @@ RunTftp (
   ValueStr = ShellCommandLineGetValue (CheckPackage, L"-c");
   if (ValueStr != NULL) {
     if (!StringToUint16 (ValueStr, &Mtftp4ConfigData.TryCount)) {
       goto Error;
     }
+
+    if (Mtftp4ConfigData.TryCount == 0) {
+      Mtftp4ConfigData.TryCount = 6;
+    }
   }
 
   ValueStr = ShellCommandLineGetValue (CheckPackage, L"-t");
   if (ValueStr != NULL) {
     if (!StringToUint16 (ValueStr, &Mtftp4ConfigData.TimeoutValue)) {
diff --git a/ShellPkg/DynamicCommand/TftpDynamicCommand/Tftp.uni b/ShellPkg/DynamicCommand/TftpDynamicCommand/Tftp.uni
index 654e42ad23..ff64912564 100644
--- a/ShellPkg/DynamicCommand/TftpDynamicCommand/Tftp.uni
+++ b/ShellPkg/DynamicCommand/TftpDynamicCommand/Tftp.uni
@@ -56,11 +56,12 @@
 "  -i interface     - Specifies an adapter name, i.e., eth0.\r\n"
 "  -l port          - Specifies the local port number. Default value is 0\r\n"
 "                     and the port number is automatically assigned.\r\n"
 "  -r port          - Specifies the remote port number. Default value is 69.\r\n"
 "  -c <retry count> - The number of times to transmit request packets and\r\n"
-"                     wait for a response. The default value is 6.\r\n"
+"                     wait for a response. The default value is 6. Set to zero\r\n"
+"                     also means to use the default value.\r\n"
 "  -t <timeout>     - The number of seconds to wait for a response after\r\n"
 "                     sending a request packet. Default value is 4s.\r\n"
 "  -s <block size>  - Specifies the TFTP blksize option as defined in RFC 2348.\r\n"
 "                     Valid range is between 8 and 65464, default value is 512.\r\n"
 "  -w <window size> - Specifies the TFTP windowsize option as defined in RFC 7440.\r\n"
-- 
2.17.1.windows.2