Provide option -c for terminal config cmd

src/avrdude.1

@@ -1263,7 +1263,7 @@ values of all matching properties are displayed.
 Show all possible values of the named configuration property (notice the
 trailing =). The one that is currently set is the only one not commented
 out. As before, wildcards or initial strings are permitted.
-.It Ar config {<-f|-v>} <property>=<value> {<-f|-v>}
+.It Ar config {<-f|-v|-c>} <property>=<value> {<-f|-v|-c>}
 Modify the named configuration property to the given value. The
 corresponding fuse or lock bits will be changed immediately but the change
 will normally only take effect the next time the part is reset, at which
@@ -1271,7 +1271,10 @@ point the fuses and lock bits are utilised. Value can either be a valid
 integer or one of the symbolic mnemonics, if known. Wildcards or initial
 strings are permitted for either the property or the assigned mnemonic
 value, but an assignment only happens if both the property and the name
-can be uniquely resolved.
+can be uniquely resolved. Option -v shows the value of the assigned
+configuration property by reading it again from the fuse. In absence of -v
+the option -c confirms the new value of the configuration property only if
+it has changed.
 .Pp
 It is quite possible, as is with direct writing to the underlying fuses
 and lock bits, to brick a part, i.e., make it unresponsive to further

src/doc/avrdude.texi

@@ -2935,8 +2935,8 @@ or after EOF on input is encountered. The @code{abort} command resets the
 cache discarding all previous writes to the flash, EEPROM, bootrow and
 usersig cache.
 
-@item config @var{[opts]}
-@cindex @code{config} @var{[opts]}
+@item config @var{[-f|-a|-v]}
+@cindex @code{config} @var{[-f|-a|-v]}
 Show all configuration properties of the part; these are usually bitfields
 in fuses or lock bits bytes that can take on values, which typically have
 a mnemonic name. Each part has their own set of configurable items.  The
@@ -2948,20 +2948,20 @@ assigned mnemonic values are the ones that are not commented out. The
 option @code{-v} increases the verbosity of the output of the config
 command.
 
-@item config @var{[opts]} @var{property} @var{[opts]}
-@cindex @code{config} @var{[opts]} @var{property} @var{[opts]}
+@item config @var{[-f|-v]} @var{property} @var{[-f|-v]}
+@cindex @code{config} @var{[-f|-v]} @var{property} @var{[-f|-v]}
 Show the current value of the named configuration property. Wildcards or
 initial strings are permitted (but not both), in which case the current
 values of all matching properties are displayed.
 
-@item config @var{[opts]} @var{property=} @var{[opts]}
-@cindex @code{config} @var{[opts]} @var{property=} @var{[opts]}
+@item config @var{[-f|-v]} @var{property=} @var{[-f|-v]}
+@cindex @code{config} @var{[-f|-v]} @var{property=} @var{[-f|-v]}
 Show all possible values of the named configuration property (notice the
 trailing @code{=}). The one that is currently set is the only one not
 commented out. As before, wildcards or initial strings are permitted.
 
-@item config @var{[opts]} @var{property=value} @var{[opts]}
-@cindex @code{config} @var{[opts]} @var{property=value} @var{[opts]}
+@item config @var{[-f|-v|-c]} @var{property=value} @var{[-f|-v|-c]}
+@cindex @code{config} @var{[-f|-v|-c]} @var{property=value} @var{[-f|-v|-c]}
 Modify the named configuration property to the given value. The
 corresponding fuse or lock bits will be changed immediately but the change
 will normally only take effect the next time the part is reset, at which
@@ -2969,7 +2969,10 @@ point the fuses and lock bits are utilised. Value can either be a valid
 integer or one of the symbolic mnemonics, if known. Wildcards or initial
 strings are permitted for either the property or the assigned mnemonic
 value, but an assignment only happens if both the property and the name
-can be uniquely resolved.
+can be uniquely resolved. Option @code{-v} shows the value of the assigned
+configuration property by reading it again from the fuse. In absence of
+@code{-v} the option @code{-c} confirms the new value of the configuration
+property only if it has changed.
 
 It is quite possible, as is with direct writing to the underlying fuses
 and lock bits, to brick a part, i.e., make it unresponsive to further

src/term.c

@@ -1387,7 +1387,7 @@ typedef struct {
 } Cnfg;
 
 typedef struct {                // Context parameters to be passed to functions
-  int verb, allscript, flheaders, allv, vmax, printfactory;
+  int verb, confirm, allscript, flheaders, allv, vmax, printfactory;
 } Cfg_opts;
 
 // Cache the contents of the fuse and lock bits memories that a particular Configitem is involved in
@@ -1694,6 +1694,9 @@ static int cmd_config(const PROGRAMMER *pgm, const AVRPART *p, int argc, const c
         case 'v':
           o.verb++;
           break;
+        case 'c':
+          o.confirm++;
+          break;
         case 'a':
           o.allscript++;        // Fall through
         case 'f':
@@ -1719,6 +1722,7 @@ static int cmd_config(const PROGRAMMER *pgm, const AVRPART *p, int argc, const c
       "    -f show value of fuse and lock bit memories as well\n"
       "    -a output an initialisation script with all possible assignments\n"
       "    -v increase verbosity, show explanations alongside output\n"
+      "    -c confirm new value of changed configuration properties\n"
       "    -h show this help message\n"
       "\n"
       "Config alone shows all property names and current settings of the part's\n"
@@ -1973,7 +1977,9 @@ static int cmd_config(const PROGRAMMER *pgm, const AVRPART *p, int argc, const c
     goto finished;
   }
 
+  int confirm = 0;
   if(towrite.i != fusel.current) {
+    confirm = o.confirm;
     for(int i = 0; i < mem->size; i++)
       if(led_write_byte(pgm, p, mem, i, towrite.b[i]) < 0) {
         pmsg_error("(config) cannot write to %s's %s memory\n", p->desc, mem->desc);
@@ -1983,7 +1989,7 @@ static int cmd_config(const PROGRAMMER *pgm, const AVRPART *p, int argc, const c
   }
 
   const char *av[] = { "confirm", cc[ci].t->name, NULL };
-  if(o.verb > 0 && !str_eq(argv[0], "confirm"))
+  if((confirm || o.verb > 0) && !str_eq(argv[0], "confirm"))
     cmd_config(pgm, p, 2, av);
 
 finished: