[GitHub] sjanc commented on a change in pull request #601: nimble/ll: Fix AUX_ADV_IND packets handling during advertising

[gi...@git.apache.org]

sjanc commented on a change in pull request #601: nimble/ll: Fix AUX_ADV_IND packets handling during advertising
URL: https://github.com/apache/mynewt-core/pull/601#discussion_r142898579
 
 

 ##########
 File path: net/nimble/controller/src/ble_ll_adv.c
 ##########
 @@ -1310,20 +1308,40 @@ ble_ll_set_adv_secondary_start_time(struct ble_ll_adv_sm *advsm)
 {
     static const uint8_t bits[8] = {0, 1, 1, 2, 1, 2, 2, 3};
     struct ble_ll_sched_item *sched = &advsm->adv_sch;
-    uint32_t ext_duration;
+    uint32_t adv_pdu_dur;
+    uint32_t adv_event_dur;
     uint8_t chans;
 
     assert(advsm->adv_chanmask <= BLE_HCI_ADV_CHANMASK_DEF);
 
     chans = bits[advsm->adv_chanmask];
 
-    ext_duration = (int32_t)(sched->end_time - sched->start_time);
-    ext_duration *= chans;
-    ext_duration += os_cputime_usecs_to_ticks(BLE_LL_IFS) * (chans -1);
+    /*
+     * 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.
+     */
 
 Review comment:
   we could have stats for this
 
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