diff options
| -rw-r--r-- | src/host/layer23/src/mobile/gsm48_rr.c | 30 |
1 files changed, 23 insertions, 7 deletions
diff --git a/src/host/layer23/src/mobile/gsm48_rr.c b/src/host/layer23/src/mobile/gsm48_rr.c index c8fb057c..b00674d4 100644 --- a/src/host/layer23/src/mobile/gsm48_rr.c +++ b/src/host/layer23/src/mobile/gsm48_rr.c @@ -3569,7 +3569,7 @@ static int gsm48_rr_rx_chan_modify(struct osmocom_ms *ms, struct msgb *msg) int payload_len = msgb_l3len(msg) - sizeof(*gh) - sizeof(*cm); struct gsm48_rr_cd *cd = &rr->cd_now; uint8_t ch_type, ch_subch, ch_ts; - uint8_t cause; + int rc; LOGP(DRR, LOGL_INFO, "CHANNEL MODE MODIFY\n"); @@ -3601,14 +3601,30 @@ static int gsm48_rr_rx_chan_modify(struct osmocom_ms *ms, struct msgb *msg) gsm_print_arfcn(cd->arfcn), ch_ts, ch_subch, cd->tsc, cm->mode); } - /* mode */ - cause = gsm48_rr_check_mode(ms, cd->chan_nr, cm->mode); - if (cause) - return gsm48_rr_tx_rr_status(ms, cause); + + /** + * According to 3GPP TS 04.08, section 3.4.6.1.3 + * "Abnormal cases" of "channel mode modify procedure", + * if the MS doesn't support the indicated channel mode, + * it shall retain the old mode and return the associated + * channel mode information in the ACKNOWLEDGE message. + */ + + /* Check if we support this channel mode */ + rc = gsm48_rr_check_mode(ms, cd->chan_nr, cm->mode); + if (rc) + goto ack; + + /* Attempt to apply this mode */ + rc = gsm48_rr_set_mode(ms, cd->chan_nr, cm->mode); + if (rc) + goto ack; + + /* Finally set (a new) mode */ cd->mode = cm->mode; - gsm48_rr_set_mode(ms, cd->chan_nr, cd->mode); - return gsm48_rr_tx_chan_modify_ack(ms, &cm->chan_desc, cm->mode); +ack: + return gsm48_rr_tx_chan_modify_ack(ms, &cm->chan_desc, cd->mode); } /* 9.1.3 sending ASSIGNMENT COMPLETE */ |