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Bluetooth: controller: corrected time stamps for unframed RX

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Corrected an omission in the ISO-AL that required an SDU interval to
be added to the reconstructed RX time stamps for each SDU after the
first.

Signed-off-by: Nirosharn Amarasinghe <niag@demant.com>
This commit is contained in:
Nirosharn Amarasinghe 2022-11-30 09:42:43 +01:00 • committed by Fabio Baltieri
commit 8510ecf6e3
2 changed files with 36 additions and 1 deletions
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36
subsys/bluetooth/controller/ll_sw/isoal.c
View file

@ -208,6 +208,7 @@ isoal_status_t isoal_sink_create(
session->handle = handle;
session->framed = framed;
session->sdu_interval = sdu_interval;
session->burst_number = burst_number;
/* Todo: Next section computing various constants, should potentially be a
* function in itself as a number of the dependencies could be changed while
@ -703,6 +704,7 @@ static isoal_status_t isoal_rx_unframed_consume(struct isoal_sink *sink,
if (sp->fsm == ISOAL_START) {
struct isoal_sdu_produced *sdu;
uint32_t anchorpoint;
uint16_t sdu_offset;
int32_t latency;
sp->sdu_status = ISOAL_SDU_STATUS_VALID;
@ -711,11 +713,43 @@ static isoal_status_t isoal_rx_unframed_consume(struct isoal_sink *sink,
session->seqn++;
seq_err = false;
/* Todo: anchorpoint must be reference anchor point, should be fixed in LL */
/* The incoming time stamp for each PDU is expected to be the
* CIS / BIS reference anchor point. SDU reference point is
* reconstructed by adding the precalculated latency constant.
*
* BT Core V5.3 : Vol 6 Low Energy Controller : Part G IS0-AL:
* 3.2.2 SDU synchronization reference using unframed PDUs:
*
* The CIS reference anchor point is computed excluding any
* retransmissions or missed subevents and shall be set to the
* start of the isochronous event in which the first PDU
* containing the SDU could have been transferred.
*
* The BIG reference anchor point is the anchor point of the BIG
* event that the PDU is associated with.
*/
anchorpoint = meta->timestamp;
latency = session->latency_unframed;
sdu = &sp->sdu;
sdu->timestamp = isoal_get_wrapped_time_us(anchorpoint, latency);
/* If there are multiple SDUs in an ISO interval
* (SDU interval < ISO Interval) every SDU after the first
* should add an SDU interval to the time stamp.
*
* BT Core V5.3 : Vol 6 Low Energy Controller : Part G IS0-AL:
* 3.2.2 SDU synchronization reference using unframed PDUs:
*
* All PDUs belonging to a burst as defined by the configuration
* of BN have the same reference anchor point. When multiple
* SDUs have the same reference anchor point, the first SDU uses
* the reference anchor point timing. Each subsequent SDU
* increases the SDU synchronization reference timing with one
* SDU interval.
*/
sdu_offset = (meta->payload_number % session->burst_number) / session->pdus_per_sdu;
sdu->timestamp = isoal_get_wrapped_time_us(sdu->timestamp,
sdu_offset * session->sdu_interval);
} else {
sp->pdu_cnt++;
}

1
subsys/bluetooth/controller/ll_sw/isoal.h
View file

@ -262,6 +262,7 @@ struct isoal_sink_session {
uint16_t handle;
uint8_t pdus_per_sdu;
uint8_t framed;
uint8_t burst_number;
uint32_t sdu_interval;
uint32_t latency_unframed;
uint32_t latency_framed;