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nimble/ll: Fix calculations for aux scheduling

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We need to take scheduling offset into account when calculating
advertising event duration.
This commit is contained in:
Andrzej Kaczmarek
2022-09-12 21:26:14 +02:00
parent 2c3c3bf82c
commit fbeb4b7506
1 changed files with 9 additions and 19 deletions
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nimble/controller/src/ble_ll_adv.c
+9 -19
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@@ -1674,28 +1674,18 @@ ble_ll_adv_aux_set_start_time(struct ble_ll_adv_sm *advsm)
chans = bits[advsm->adv_chanmask];
/*
* We want to schedule auxiliary packet as soon as possible after the end
* of advertising event, but no sooner than T_MAFS. The interval between
* advertising packets is 250 usecs (8.19 ticks) on LE Coded and a bit less
* on 1M, but it can vary a bit due to scheduling which we can't really
* control. Since we round ticks up for both interval and T_MAFS, we still
* have some margin here. The worst thing that can happen is that we skip
* last advertising packet which is not a bit problem so leave it as-is, no
* need to make code more complicated.
*/
/*
* XXX: this could be improved if phy has TX-TX transition with controlled
* or predefined interval, but since it makes advertising code even
* more complicated let's skip it for now...
*/
adv_pdu_dur = (int32_t)(sched->end_time - sched->start_time) -
g_ble_ll_sched_offset_ticks;
/* 9 is 8.19 ticks rounded up - see comment above */
adv_event_dur = (adv_pdu_dur * chans) + (9 * (chans - 1));
/* The interval between advertising PDUs may vary due to scheduling, but in
* general we reserve 3 ticks for end-to-schedule time and add scheduler
* offset. That should be more that enough to make sure there's at least
* T_mafs delay between last advertising PDU and auxiliary PDU.
*
* TODO we can make this much more efficient with TX-TX transition
*/
adv_event_dur = (adv_pdu_dur * chans) +
((3 + g_ble_ll_sched_offset_ticks) * (chans - 1));
advsm->aux[0].start_time = advsm->adv_event_start_time + adv_event_dur +
ble_ll_tmr_u2t_up(BLE_LL_MAFS +