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dyn PDCH: allow allocating TCH/F on TCH/F_PDCH slots 

Remove check for dyn PDCH in _lc_find_trx(), instead call _lc_find_trx() via
_lc_find_bts() several times, so that pure TCH/F is preferred to TCH/F_PDCH.
Add this logic next to the other channel match decisions in chan_alloc().

BTW, the removed check in _lc_find_trx() whether PDCH is active is not
necessary, as described in the added comment for lchan_alloc().

Original patch idea by jolly, but split in two and implemented differently by
nhofmeyr.

Change-Id: I0c728b922656be03588b775638b610a93f8187d5
This commit is contained in:
Neels Hofmeyr 2016-06-06 12:53:25 +02:00 committed by Harald Welte
parent 0434efa077
commit a66852525a
1 changed files with 29 additions and 9 deletions
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38
openbsc/src/libbsc/chan_alloc.c
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@ -96,14 +96,7 @@ _lc_find_trx(struct gsm_bts_trx *trx, enum gsm_phys_chan_config pchan)
ts = &trx->ts[j];
if (!ts_is_usable(ts))
continue;
/* ip.access dynamic TCH/F + PDCH combination */
if (ts->pchan == GSM_PCHAN_TCH_F_PDCH &&
pchan == GSM_PCHAN_TCH_F) {
/* we can only consider such a dynamic channel
* if the PDCH is currently inactive */
if (ts->flags & TS_F_PDCH_MODE)
continue;
} else if (ts->pchan != pchan)
if (ts->pchan != pchan)
continue;
/* check if all sub-slots are allocated yet */
for (ss = 0; ss < subslots_per_pchan[pchan]; ss++) {
@ -140,7 +133,12 @@ _lc_find_bts(struct gsm_bts *bts, enum gsm_phys_chan_config pchan)
return NULL;
}
/* Allocate a logical channel */
/* Allocate a logical channel.
*
* For TCH/F, we may return a dynamic TCH/F_PDCH channel (but prefer a pure
* TCH/F). If we pick a TCH/F_PDCH time slot, PDCH will be disabled later on;
* there is no need to check whether PDCH mode is currently active, here.
*/
struct gsm_lchan *lchan_alloc(struct gsm_bts *bts, enum gsm_chan_t type,
int allow_bigger)
{
@ -182,6 +180,14 @@ struct gsm_lchan *lchan_alloc(struct gsm_bts *bts, enum gsm_chan_t type,
if (lchan)
type = GSM_LCHAN_TCH_F;
}
/* try dynamic TCH/F_PDCH */
if (lchan == NULL) {
lchan = _lc_find_bts(bts, GSM_PCHAN_TCH_F_PDCH);
/* TCH/F_PDCH will be used as TCH/F */
if (lchan)
type = GSM_LCHAN_TCH_F;
}
}
break;
case GSM_LCHAN_TCH_F:
@ -192,6 +198,14 @@ struct gsm_lchan *lchan_alloc(struct gsm_bts *bts, enum gsm_chan_t type,
if (lchan)
type = GSM_LCHAN_TCH_H;
}
/* If we don't have TCH/H either, try dynamic TCH/F_PDCH */
if (!lchan) {
lchan = _lc_find_bts(bts, GSM_PCHAN_TCH_F_PDCH);
/* TCH/F_PDCH used as TCH/F -- here, type is already
* set to GSM_LCHAN_TCH_F, but for clarity's sake... */
if (lchan)
type = GSM_LCHAN_TCH_F;
}
break;
case GSM_LCHAN_TCH_H:
lchan =_lc_find_bts(bts, GSM_PCHAN_TCH_H);
@ -201,6 +215,12 @@ struct gsm_lchan *lchan_alloc(struct gsm_bts *bts, enum gsm_chan_t type,
if (lchan)
type = GSM_LCHAN_TCH_F;
}
/* If we don't have TCH/F either, try dynamic TCH/F_PDCH */
if (!lchan) {
lchan = _lc_find_bts(bts, GSM_PCHAN_TCH_F_PDCH);
if (lchan)
type = GSM_LCHAN_TCH_F;
}
break;
default:
LOGP(DRLL, LOGL_ERROR, "Unknown gsm_chan_t %u\n", type);