diff --git a/src/gprs_rlcmac_sched.cpp b/src/gprs_rlcmac_sched.cpp index 5427e52b..00f740ed 100644 --- a/src/gprs_rlcmac_sched.cpp +++ b/src/gprs_rlcmac_sched.cpp @@ -485,12 +485,28 @@ int gprs_rlcmac_rcv_rts_block(struct gprs_rlcmac_bts *bts, gsmtap_cat = tx_is_egprs ? PCU_GSMTAP_C_DL_DATA_EGPRS : PCU_GSMTAP_C_DL_DATA_GPRS; } - /* Prio 3: send dummy contol message */ - else if ((msg = sched_dummy())) { - /* increase counter */ - gsmtap_cat = PCU_GSMTAP_C_DL_DUMMY; - } else { - return -ENOMEM; + /* Prio 3: send dummy control message if need to poll or USF */ + else { + /* If there's no TBF attached to this PDCH, we can early skip + * since there's nothing to transmit nor to poll/USF. This way + * we help BTS energy saving (on TRX!=C0) by sending nothing + * instead of a dummy block. The early return is done here and + * not at the start of the function because the condition below + * (num_tbfs==0) may not be enough, because temporary dummy TBFs + * created to send Imm Ass Rej (see handle_tbf_reject()) don't + * have a TFI assigned and hence are not attached to the PDCH + * TS, so they don't show up in the count below. + */ + const unsigned num_tbfs = pdch->num_tbfs(GPRS_RLCMAC_DL_TBF) + + pdch->num_tbfs(GPRS_RLCMAC_UL_TBF); + if (trx != 0 && num_tbfs == 0) + return 0; + if ((msg = sched_dummy())) { + /* increase counter */ + gsmtap_cat = PCU_GSMTAP_C_DL_DUMMY; + } else { + return -ENOMEM; + } } if (tx_is_egprs && pdch->has_gprs_only_tbf_attached()) {