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Bluetooth: controller: Introduce preferred central conn spacing config

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Adds configuration BT_CTLR_SCHED_ADVANCED_CENTRAL_CONN_SPACING to enable
per-application preferred central connection spacing. This is an
extension of feature BT_CTLR_SCHED_ADVANCED, which when enabled, adds
user defined spacing between existing, and new central initiated
connections.

This is crucial for ensuring that centrals acting as ACL connection
based multi-channel streaming sources do not get overlapping
connections, and that spacing allows full frame transfer without
scheduling collision.

Due to the simple, compile-time configuration, use is limited to
specific applications in which the specified spacing is required.

Signed-off-by: Morten Priess <mtpr@oticon.com>
This commit is contained in:
Morten Priess 2021-11-04 16:37:19 +01:00 • committed by Christopher Friedt
commit 7a6666a0e7
2 changed files with 28 additions and 1 deletions
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20
subsys/bluetooth/controller/Kconfig.ll_sw_split
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@ -358,6 +358,26 @@ config BT_CTLR_SCHED_ADVANCED
Disabling this feature will lead to overlapping role in timespace
leading to skipped events amongst active roles.
config BT_CTLR_SCHED_ADVANCED_CENTRAL_CONN_SPACING
int "Advanced scheduling central preferred connection spacing"
depends on BT_CTLR_SCHED_ADVANCED
default 0
help
The central preferred connection spacing defines an additional spacing
in microseconds, added to the fixed ~1250 us spacing obtained by enabling
BT_CTLR_SCHED_ADVANCED. Specifying 0 (default) will obtain a spacing of
~1250 us, whereas specifying 1250 will yield a spacing of ~2500 us.
The spacing is defined as the distance in time between the anchor points
of the established central role connections.
The precision is determined by the resolution of the platform dependent
ticker clock.
When spefifying values above 6.25 ms, the spacing may be unobtainable if
the connection interval becomes smaller than the total spacing. In that
case, modulo is applied and a total spacing of 15 ms on a 10 ms connection
interval yields 5 ms spacing.
For multiple connections, it may become impossible to honor the preferred
spacing, in which case overlapping will occur.
config BT_CTLR_LLL_PRIO
int "Lower Link Layer (Radio) IRQ priority" if (BT_CTLR_ULL_LLL_PRIO_SUPPORT && !BT_CTLR_ZLI)
range 0 3 if SOC_SERIES_NRF51X