Fix issue where DTMF CID detect was placing channels into signed linear mode

made analog_set_linear_mode return back the mode that was being overwritten 
so it could be restored later. 


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@215608 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_dahdi.c

@@ -1992,12 +1992,20 @@ static void my_unlock_private(void *pvt)
 	ast_mutex_unlock(&p->lock);
 }
 
+/* linear_mode = 0 - turn linear mode off, >0 - turn linear mode on
+* 	returns the last value of the linear setting 
+*/ 
 static int my_set_linear_mode(void *pvt, int idx, int linear_mode)
 {
 	struct dahdi_pvt *p = pvt;
-	if (!linear_mode)
-		linear_mode = p->subs[idx].linear;
-	return dahdi_setlinear(p->subs[idx].dfd, linear_mode);
+	int oldval;
+	
+    if (0 > linear_mode || !dahdi_setlinear(p->subs[idx].dfd, linear_mode)) {
+        return -1;
+    }
+	oldval = p->subs[idx].linear;
+	p->subs[idx].linear = linear_mode;
+	return oldval;
 }
 
 static int get_alarms(struct dahdi_pvt *p);
@@ -3494,11 +3502,7 @@ static void dahdi_close_ss7_fd(struct dahdi_ss7 *ss7, int fd_num)
 
 static int dahdi_setlinear(int dfd, int linear)
 {
-	int res;
-	res = ioctl(dfd, DAHDI_SETLINEAR, &linear);
-	if (res)
-		return res;
-	return 0;
+	return ioctl(dfd, DAHDI_SETLINEAR, &linear);
 }
 
 

channels/sig_analog.c

@@ -770,6 +770,7 @@ static int analog_check_confirmanswer(struct analog_pvt *p)
 static int analog_set_linear_mode(struct analog_pvt *p, int index, int linear_mode)
 {
 	if (p->calls->set_linear_mode) {
+		/* Return provides old linear_mode setting or error indication */
 		return p->calls->set_linear_mode(p->chan_pvt, index, linear_mode);
 	}
 	return -1;
@@ -2035,11 +2036,12 @@ static void *__analog_ss_thread(void *data)
 			/* If set to use DTMF CID signalling, listen for DTMF */
 			if (p->cid_signalling == CID_SIG_DTMF) {
 				int i = 0;
+				int oldlinearity; 
 				cs = NULL;
 				ast_debug(1, "Receiving DTMF cid on "
 					"channel %s\n", chan->name);
 
-				analog_set_linear_mode(p, index, 0);
+				oldlinearity = analog_set_linear_mode(p, index, 0);
 
 				res = 2000;
 				for (;;) {
@@ -2066,7 +2068,7 @@ static void *__analog_ss_thread(void *data)
 				}
 				dtmfbuf[i] = '\0';
 
-				analog_set_linear_mode(p, index, 1);
+				analog_set_linear_mode(p, index, oldlinearity);
 
 				/* Got cid and ring. */
 				ast_debug(1, "CID got string '%s'\n", dtmfbuf);