mpegts: ensure that potentially valid muxes are not ignored

It's possible a mux is not tunable, yet that doesn't imply the presence
of a free tuner means its invalid. It could just be that its an S2 mux
with only an S tuner available (just one example).

src/input/mpegts/mpegts_mux.c

@@ -374,7 +374,11 @@ mpegts_mux_start
   
   if (!tune) {
     tvhdebug("mpegts", "%s - no free input (fail=%d)", buf, fail);
-    return havefree ? SM_CODE_TUNING_FAILED : SM_CODE_NO_FREE_ADAPTER;
+    LIST_FOREACH(mmi, &mm->mm_instances, mmi_mux_link)
+      if (!mmi->mmi_tune_failed)
+        return havefree ? SM_CODE_NO_VALID_ADAPTER : SM_CODE_NO_FREE_ADAPTER;
+    tvhdebug("mpegts", "%s - tuning failed", buf);
+    return SM_CODE_TUNING_FAILED;
   }
   
   return 0;

src/input/mpegts/mpegts_network.c

@@ -238,10 +238,14 @@ mpegts_network_initial_scan(void *aux)
 {
   int r;
   mpegts_network_t  *mn = aux;
-  mpegts_mux_t      *mm;
+  mpegts_mux_t      *mm, *mark = NULL;
 
   tvhtrace("mpegts", "setup initial scan for %p", mn);
   while((mm = TAILQ_FIRST(&mn->mn_initial_scan_pending_queue)) != NULL) {
+
+    /* Stop */
+    if (mm == mark) break;
+
     assert(mm->mm_initial_scan_status == MM_SCAN_PENDING);
     r = mpegts_mux_subscribe(mm, "initscan", 1);
 
@@ -255,8 +259,21 @@ mpegts_network_initial_scan(void *aux)
       continue;
     }
 
-    /* Remove */
     TAILQ_REMOVE(&mn->mn_initial_scan_pending_queue, mm, mm_initial_scan_link);
+
+    /* Available tuners can't be used
+     * Note: this is subtly different it does not imply there are no free
+     *       tuners, just that none of the free ones can service this mux.
+     *       therefore we move this to the back of the queue and see if we
+     *       can find one we can tune
+     */
+    if (r == SM_CODE_NO_VALID_ADAPTER) {
+      if (!mark) mark = mm;
+      TAILQ_INSERT_TAIL(&mn->mn_initial_scan_pending_queue, mm, mm_initial_scan_link);
+      continue;
+    }
+
+    /* Remove */
     mpegts_mux_initial_scan_fail(mm);
   }
   gtimer_arm(&mn->mn_initial_scan_timer, mpegts_network_initial_scan, mn, 10);

src/tvheadend.h

@@ -371,6 +371,7 @@ typedef enum {
 #define SM_CODE_BAD_SIGNAL                205
 #define SM_CODE_NO_SOURCE                 206
 #define SM_CODE_NO_SERVICE                207
+#define SM_CODE_NO_VALID_ADAPTER          308
 
 #define SM_CODE_ABORTED                   300