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Bluetooth: Controller: Fix minimum offset for subsequent CISes

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Fix CIS offset calculation by Central for subsequent CISes
such that when compensating for dissimilar ACL and ISO
intervals, ensure that minimum offset does not cause a
collision between the ACL and the CIS event at the instant.

Fixes commit 3b3d53f09e ("Bluetooth: Controller: Fix CIS
offset_min for dissimilar interval").

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>
This commit is contained in:
Vinayak Kariappa Chettimada 2023-05-14 15:32:02 +05:30 committed by Benjamin Cabé
parent cffb66f5c6
commit 478cace022
1 changed files with 19 additions and 3 deletions
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22
subsys/bluetooth/controller/ll_sw/ull_central_iso.c
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@ -1022,6 +1022,7 @@ static void mfy_cig_offset_get(void *param)
struct ll_conn_iso_stream *cis;
struct ll_conn_iso_group *cig;
uint32_t conn_interval_us;
uint32_t offset_limit_us;
uint32_t ticks_to_expire;
uint32_t offset_max_us;
uint32_t offset_min_us;
@ -1031,17 +1032,25 @@ static void mfy_cig_offset_get(void *param)
cis = param;
cig = cis->group;
/* Find a free offset that does not overlap other periodically scheduled
* states/roles.
*/
err = ull_sched_conn_iso_free_offset_get(cig->ull.ticks_slot,
&ticks_to_expire);
LL_ASSERT(!err);
/* Calculate the offset for the select CIS in the CIG */
offset_min_us = HAL_TICKER_TICKS_TO_US(ticks_to_expire) +
(EVENT_TICKER_RES_MARGIN_US << 2U);
offset_min_us += cig->sync_delay - cis->sync_delay;
/* Ensure the offset is not greater than the ACL interval, considering
* the minimum CIS offset requirement.
*/
conn = ll_conn_get(cis->lll.acl_handle);
conn_interval_us = (uint32_t)conn->lll.interval * CONN_INT_UNIT_US;
while (offset_min_us >= (conn_interval_us + PDU_CIS_OFFSET_MIN_US)) {
offset_limit_us = conn_interval_us + PDU_CIS_OFFSET_MIN_US;
while (offset_min_us >= offset_limit_us) {
offset_min_us -= conn_interval_us;
}
@ -1071,6 +1080,7 @@ static void mfy_cis_offset_get(void *param)
uint32_t cig_remainder_us;
uint32_t acl_remainder_us;
uint32_t cig_interval_us;
uint32_t offset_limit_us;
uint32_t ticks_to_expire;
uint32_t ticks_current;
uint32_t offset_min_us;
@ -1172,12 +1182,18 @@ static void mfy_cis_offset_get(void *param)
/* Compensate for the difference between ACL elapsed vs CIG elapsed */
offset_min_us += elapsed_cig_us - elapsed_acl_us;
while (offset_min_us >= (cig_interval_us + PDU_CIS_OFFSET_MIN_US)) {
/* Ensure that the minimum offset is not greater than ISO interval
* considering the select CIS in the CIG meets the minimum CIS offset
* requirement.
*/
offset_limit_us = cig_interval_us + cig->sync_delay - cis->sync_delay;
while (offset_min_us >= offset_limit_us) {
offset_min_us -= cig_interval_us;
}
/* Decrement event_count to compensate for offset_min_us greater than
* CIG interval due to offset being at least PDU_CIS_OFFSET_MIN_US.
* CIG interval.
*/
if (offset_min_us > cig_interval_us) {
cis->lll.event_count--;