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osmo-bsc
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lchan: pick proper power and ta values 

When activating an lchan, the power levels should be maximum and TA zero. Only
if a new lchan is assigned within the same cell does it make sense to take over
the previous power and TA levels.

In LCHAN_EV_ACTIVATE:

- Separate the code that copies previous encryption data. This should happen
  regardless of whether we're staying in the same cell or not.

- For the power,TA levels, take over an old lchan's values only when it is
  assigning a new lchan in the same cell.

Change-Id: I360b003398487fa6f934296ff03643c33ec61a35
This commit is contained in:
Neels Hofmeyr 2018-08-29 14:01:17 +02:00
parent f213fcbd43
commit dd6849da18
1 changed files with 15 additions and 6 deletions
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21
src/osmo-bsc/lchan_fsm.c
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@ -429,6 +429,8 @@ static void lchan_fsm_unused(struct osmo_fsm_inst *fi, uint32_t event, void *dat
{
struct lchan_activate_info *info = data;
struct gsm_lchan *lchan = lchan_fi_lchan(fi);
struct gsm_bts *bts = lchan->ts->trx->bts;
switch (event) {
case LCHAN_EV_ACTIVATE:
@ -446,18 +448,25 @@ static void lchan_fsm_unused(struct osmo_fsm_inst *fi, uint32_t event, void *dat
lchan->activate.concluded = false;
lchan->activate.re_use_mgw_endpoint_from_lchan = info->old_lchan;
if (info->old_lchan) {
if (info->old_lchan)
lchan->encr = info->old_lchan->encr;
else {
lchan->encr = (struct gsm_encr){
.alg_id = RSL_ENC_ALG_A5(0), /* no encryption */
};
}
/* If there is a previous lchan, and the new lchan is on the same cell as previous one,
* take over power and TA values. Otherwise, use max power and zero TA. */
if (info->old_lchan && info->old_lchan->ts->trx->bts == bts) {
lchan->ms_power = info->old_lchan->ms_power;
lchan->bs_power = info->old_lchan->bs_power;
lchan->rqd_ta = info->old_lchan->rqd_ta;
} else {
struct gsm_bts *bts = lchan->ts->trx->bts;
lchan->encr = (struct gsm_encr){
.alg_id = RSL_ENC_ALG_A5(0), /* no encryption */
};
lchan->ms_power = ms_pwr_ctl_lvl(bts->band, bts->ms_max_power);
lchan->bs_power = 0; /* 0dB reduction, output power = Pn */
/* From lchan_reset():
* - bs_power is still zero, 0dB reduction, output power = Pn.
* - TA is still zero, to be determined by RACH. */
}
if (info->chan_mode == GSM48_CMODE_SPEECH_AMR)