transport: make 'transport select' auto-select the first available transport if not set 51/2551/7
authorAngus Gratton <>
Tue, 24 Feb 2015 21:19:15 +0000 (08:19 +1100)
committerSpencer Oliver <>
Wed, 25 Mar 2015 21:32:49 +0000 (21:32 +0000)
This should allow most of the existing configurations for older
versions to remain compatible without forcing the user to change his
or her config to explicitly select transport.

Also in some circumstances can remove the need to chain a "-c transport
select X" when building custom configs on the command line, which seems
like a common new user pitfall.

Change-Id: Ic87a38c0b9b88e88fb6d106385efce2f39381d3d
Suggested-by: Petteri Aimonen <>
Signed-off-by: Angus Gratton <>
Reviewed-by: Paul Fertser <>
Tested-by: jenkins
Reviewed-by: Spencer Oliver <>

index cc7f6c8247c6d6c464817db190648b57681b9846..f120b569a439cfb1f9aac0b46698a0c90650ae6f 100644 (file)
@@ -3088,6 +3088,7 @@ which are not currently documented here.
 @end quotation
 @end deffn
 @deffn {Interface Driver} {hla}
 This is a driver that supports multiple High Level Adapters.
 This type of adapter does not expose some of the lower level api's
@@ -3170,11 +3171,20 @@ displays the names of the transports supported by this
 version of OpenOCD.
 @end deffn
-@deffn Command {transport select} transport_name
+@deffn Command {transport select} @option{transport_name}
 Select which of the supported transports to use in this OpenOCD session.
-The transport must be supported by the debug adapter hardware and by the
-version of OpenOCD you are using (including the adapter's driver).
-No arguments: returns name of session's selected transport.
+When invoked with @option{transport_name}, attempts to select the named
+transport.  The transport must be supported by the debug adapter
+hardware and by the version of OpenOCD you are using (including the
+adapter's driver).
+If no transport has been selected and no @option{transport_name} is
+provided, @command{transport select} auto-selects the first transport
+supported by the debug adapter.
+@command{transport select} always returns the name of the session's selected
+transport, if any.
 @end deffn
 @subsection JTAG Transport
@@ -3185,6 +3195,12 @@ JTAG transports expose a chain of one or more Test Access Points (TAPs),
 each of which must be explicitly declared.
 JTAG supports both debugging and boundary scan testing.
 Flash programming support is built on top of debug support.
+JTAG transport is selected with the command @command{transport select
+jtag}. Unless your adapter uses @ref{hla_interface,the hla interface
+driver}, in which case the command is @command{transport select
 @subsection SWD Transport
 @cindex SWD
 @cindex Serial Wire Debug
@@ -3194,6 +3210,12 @@ Debug Access Point (DAP, which must be explicitly declared.
 SWD is debug-oriented, and does not support boundary scan testing.
 Flash programming support is built on top of debug support.
 (Some processors support both JTAG and SWD.)
+SWD transport is selected with the command @command{transport select
+swd}. Unless your adapter uses @ref{hla_interface,the hla interface
+driver}, in which case the command is @command{transport select
 @deffn Command {swd newdap} ...
 Declares a single DAP which uses SWD transport.
 Parameters are currently the same as "jtag newtap" but this is
@@ -3205,11 +3227,6 @@ Wire Control Register (WCR).
 No parameters: displays current settings.
 @end deffn
-@subsection CMSIS-DAP Transport
-@cindex CMSIS-DAP
-CMSIS-DAP is an ARM-specific transport that is used to connect to
-compilant debuggers.
 @subsection SPI Transport
 @cindex SPI
 @cindex Serial Peripheral Interface
index c57064bbdde8b40d0e17c0155ea98769e7eb4367..c973e1c3a9ff783f344ee608ef5663ffd5583a4e 100644 (file)
@@ -275,20 +275,28 @@ COMMAND_HANDLER(handle_transport_list)
 static int jim_transport_select(Jim_Interp *interp, int argc, Jim_Obj * const *argv)
+       int res;
        switch (argc) {
-               case 1:         /* return/display */
+               case 1: /* autoselect if necessary, then return/display current config */
                        if (!session) {
-                               LOG_ERROR("session transport was not selected. Use 'transport select <transport>'");
-                               return JIM_ERR;
-                       } else {
-                               Jim_SetResultString(interp, session->name, -1);
-                               return JIM_OK;
+                               if (!allowed_transports) {
+                                       LOG_ERROR("Debug adapter does not support any transports? Check config file order.");
+                                       return JIM_ERR;
+                               }
+                               LOG_INFO("auto-selecting first available session transport \"%s\". "
+                                        "To override use 'transport select <transport>'.", allowed_transports[0]);
+                               res = transport_select(global_cmd_ctx, allowed_transports[0]);
+                               if (res != JIM_OK)
+                                       return res;
+                       Jim_SetResultString(interp, session->name, -1);
+                       return JIM_OK;
-               case 2:         /* assign */
+               case 2: /* assign */
                        if (session) {
                                if (!strcmp(session->name, argv[1]->bytes)) {
                                        LOG_WARNING("Transport \"%s\" was already selected", session->name);
+                                       Jim_SetResultString(interp, session->name, -1);
                                        return JIM_OK;
                                } else {
                                        LOG_ERROR("Can't change session's transport after the initial selection was made");
@@ -309,8 +317,13 @@ static int jim_transport_select(Jim_Interp *interp, int argc, Jim_Obj * const *a
                        for (unsigned i = 0; allowed_transports[i]; i++) {
-                               if (strcmp(allowed_transports[i], argv[1]->bytes) == 0)
-                                       return transport_select(global_cmd_ctx, argv[1]->bytes);
+                               if (strcmp(allowed_transports[i], argv[1]->bytes) == 0) {
+                                       if (transport_select(global_cmd_ctx, argv[1]->bytes) == ERROR_OK) {
+                                               Jim_SetResultString(interp, session->name, -1);
+                                               return JIM_OK;
+                                       }
+                                       return JIM_ERR;
+                               }
                        LOG_ERROR("Debug adapter doesn't support '%s' transport", argv[1]->bytes);
index f759e7c8df3c265f620cde7213e2bef9b88754ca..1d274cb1290cbb73e6efdd64d2ef82b529732ac0 100644 (file)
@@ -19,8 +19,8 @@
 # them more uniformly irlen too...)
 if [catch {transport select}] {
echo "Info : session transport was not selected, defaulting to JTAG"
- transport select jtag
 echo "Error: unable to select a session transport. Can't continue."
+  shutdown
 proc swj_newdap {chip tag args} {

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