fix gsm_bts_get_cbch(): CBCH can be allocated on Cn

According to 3GPP TS 45.002, table 3, unlike the CCCH+SDCCH/4+CBCH
combination, which can only be allocated on C0/TS0, the SDCCH/8+CBCH
can be allocated on C0..n/TS0..3.  In other words, having CBCH on
e.g. C1/TS2 is perfectly legal.  This is why in gsm_bts_get_cbch()
we should check all transceivers, not just the C0.

Without this change osmo-bts does not send CBCH Load Indications
at all if the CBCH is allocated on C1..n.

Change-Id: Ib5976783b53521047fbdfc18e0e236e8bce8eaae
Related: osmo-bsc.git Ie79ccff4f8f0f1134757ec0c35e18b58081cc158
Related: SYS#5905
This commit is contained in:
Vadim Yanitskiy 2022-03-31 19:52:26 +03:00
parent b147878f9e
commit 5bb7031366
1 changed files with 11 additions and 10 deletions

View File

@ -883,22 +883,23 @@ int bts_supports_cm(const struct gsm_bts *bts,
/* return the gsm_lchan for the CBCH (if it exists at all) */
struct gsm_lchan *gsm_bts_get_cbch(struct gsm_bts *bts)
{
struct gsm_lchan *lchan = NULL;
struct gsm_bts_trx *trx = bts->c0;
/* According to 3GPP TS 45.002, table 3, CBCH can be allocated
* either on C0/TS0 (CCCH+SDCCH4) or on C0..n/TS0..3 (SDCCH/8). */
if (trx->ts[0].pchan == GSM_PCHAN_CCCH_SDCCH4_CBCH)
lchan = &trx->ts[0].lchan[2];
else {
int i;
for (i = 0; i < 8; i++) {
if (trx->ts[i].pchan == GSM_PCHAN_SDCCH8_SACCH8C_CBCH) {
lchan = &trx->ts[i].lchan[2];
break;
}
return &trx->ts[0].lchan[2]; /* C0/TS0 */
llist_for_each_entry(trx, &bts->trx_list, list) { /* C0..n */
unsigned int tn;
for (tn = 0; tn <= 3; tn++) { /* TS0..3 */
struct gsm_bts_trx_ts *ts = &trx->ts[tn];
if (ts->pchan == GSM_PCHAN_SDCCH8_SACCH8C_CBCH)
return &ts->lchan[2];
}
}
return lchan;
return NULL;
}
/* BCCH carrier power reduction (see 3GPP TS 45.008, section 7.1) */