Fix function nr_get_prach_mu for L839

function returns mu of UL BWP if msg1-SubcarrierSpacing absent instead
of asserting. The mu retured by this function is used to compute the
slot number of PRACH. In case of long format, the slot number is as per
UL mu.

openair2/LAYER2/NR_MAC_COMMON/nr_mac_common.c

@@ -5266,7 +5266,9 @@ int get_FeedbackDisabled(NR_DownlinkHARQ_FeedbackDisabled_r17_t *downlinkHARQ_Fe
   return (downlinkHARQ_FeedbackDisabled_r17->buf[byte_index] >> (7 - bit_index)) & 1;
 }
 
-int nr_get_prach_mu(const NR_MsgA_ConfigCommon_r16_t *msgacc, const NR_RACH_ConfigCommon_t *rach_ConfigCommon)
+int nr_get_prach_or_ul_mu(const NR_MsgA_ConfigCommon_r16_t *msgacc,
+                          const NR_RACH_ConfigCommon_t *rach_ConfigCommon,
+                          const int ul_mu)
 {
   int mu;
 
@@ -5278,7 +5280,8 @@ int nr_get_prach_mu(const NR_MsgA_ConfigCommon_r16_t *msgacc, const NR_RACH_Conf
     // Choose Subcarrier Spacing of configuration file of 4-Step
     mu = *rach_ConfigCommon->msg1_SubcarrierSpacing;
   } else
-    AssertFatal(false, "PRACH subcarrier spacing mandatory present for L139, not supported otherwise\n");
+    // Return invalid UL mu
+    mu = ul_mu;
 
   return mu;
 }

openair2/LAYER2/NR_MAC_COMMON/nr_mac_common.h

@@ -334,6 +334,6 @@ int get_nrofHARQ_ProcessesForPDSCH(const NR_UE_ServingCell_Info_t *sc_info);
 
 int get_nrofHARQ_ProcessesForPUSCH(const NR_UE_ServingCell_Info_t *sc_info);
 
-int nr_get_prach_mu(const NR_MsgA_ConfigCommon_r16_t *msgacc, const NR_RACH_ConfigCommon_t *rach_ConfigCommon);
+int nr_get_prach_or_ul_mu(const NR_MsgA_ConfigCommon_r16_t *msgacc, const NR_RACH_ConfigCommon_t *rach_ConfigCommon, const int ul_mu);
 
 #endif

openair2/LAYER2/NR_MAC_UE/nr_ue_scheduler.c

@@ -1849,7 +1849,8 @@ static void build_ro_list(NR_UE_MAC_INST_t *mac)
   int unpaired = mac->phy_config.config_req.cell_config.frame_duplex_type;
 
   const int64_t *prach_config_info_p = get_prach_config_info(mac->frequency_range, config_index, unpaired);
-  int mu = nr_get_prach_mu(mac->current_UL_BWP->msgA_ConfigCommon_r16, setup);
+  const int ul_mu = mac->current_UL_BWP->scs;
+  const int mu = nr_get_prach_or_ul_mu(mac->current_UL_BWP->msgA_ConfigCommon_r16, setup, ul_mu);
 
   // Identify the proper PRACH Configuration Index table according to the operating frequency
   LOG_D(NR_MAC,"mu = %u, PRACH config index  = %u, unpaired = %u\n", mu, config_index, unpaired);

openair2/LAYER2/NR_MAC_gNB/gNB_scheduler_RA.c

@@ -92,7 +92,8 @@ static int16_t ssb_index_from_prach(module_id_t module_idP,
   NR_MsgA_ConfigCommon_r16_t *msgacc = NULL;
   if (scc->uplinkConfigCommon->initialUplinkBWP->ext1 && scc->uplinkConfigCommon->initialUplinkBWP->ext1->msgA_ConfigCommon_r16)
     msgacc = scc->uplinkConfigCommon->initialUplinkBWP->ext1->msgA_ConfigCommon_r16->choice.setup;
-  int mu = nr_get_prach_mu(msgacc, rach_ConfigCommon);
+  const int ul_mu = scc->uplinkConfigCommon->frequencyInfoUL->scs_SpecificCarrierList.list.array[0]->subcarrierSpacing;
+  const int mu = nr_get_prach_or_ul_mu(msgacc, rach_ConfigCommon, ul_mu);
 
   get_nr_prach_info_from_index(config_index,
 			       (int)frameP,
@@ -199,7 +200,8 @@ void find_SSB_and_RO_available(gNB_MAC_INST *nrmac)
   NR_MsgA_ConfigCommon_r16_t *msgacc = NULL;
   if (scc->uplinkConfigCommon->initialUplinkBWP->ext1 && scc->uplinkConfigCommon->initialUplinkBWP->ext1->msgA_ConfigCommon_r16)
     msgacc = scc->uplinkConfigCommon->initialUplinkBWP->ext1->msgA_ConfigCommon_r16->choice.setup;
-  int mu = nr_get_prach_mu(msgacc, rach_ConfigCommon);
+  const int ul_mu = scc->uplinkConfigCommon->frequencyInfoUL->scs_SpecificCarrierList.list.array[0]->subcarrierSpacing;
+  const int mu = nr_get_prach_or_ul_mu(msgacc, rach_ConfigCommon, ul_mu);
 
   // prach is scheduled according to configuration index and tables 6.3.3.2.2 to 6.3.3.2.4
   get_nr_prach_occasion_info_from_index(config_index,
@@ -366,7 +368,6 @@ void schedule_nr_prach(module_id_t module_idP, frame_t frameP, sub_frame_t slotP
   NR_MsgA_ConfigCommon_r16_t *msgacc = NULL;
   if (scc->uplinkConfigCommon->initialUplinkBWP->ext1 && scc->uplinkConfigCommon->initialUplinkBWP->ext1->msgA_ConfigCommon_r16)
     msgacc = scc->uplinkConfigCommon->initialUplinkBWP->ext1->msgA_ConfigCommon_r16->choice.setup;
-  int mu = nr_get_prach_mu(msgacc, rach_ConfigCommon);
   int slots_frame = gNB->frame_structure.numb_slots_frame;
   int index = ul_buffer_index(frameP, slotP, slots_frame, gNB->UL_tti_req_ahead_size);
   nfapi_nr_ul_tti_request_t *UL_tti_req = &RC.nrmac[module_idP]->UL_tti_req_ahead[0][index];
@@ -385,6 +386,8 @@ void schedule_nr_prach(module_id_t module_idP, frame_t frameP, sub_frame_t slotP
     int bwp_start = NRRIV2PRBOFFSET(scc->uplinkConfigCommon->initialUplinkBWP->genericParameters.locationAndBandwidth, MAX_BWP_SIZE);
 
     uint8_t fdm = cfg->prach_config.num_prach_fd_occasions.value;
+    const int ul_mu = scc->uplinkConfigCommon->frequencyInfoUL->scs_SpecificCarrierList.list.array[0]->subcarrierSpacing;
+    const int mu = nr_get_prach_or_ul_mu(msgacc, rach_ConfigCommon, ul_mu);
     // prach is scheduled according to configuration index and tables 6.3.3.2.2 to 6.3.3.2.4
     if (get_nr_prach_info_from_index(config_index,
                                      (int)frameP,