bluetooth: controller: Add lowest frame space config

This option has been added to the controller which is
required to be enabled to get support for the lowest frame
spaces.

This commit adds a config and call to sdc if the config
is enabled.

Signed-off-by: Sean Madigan <[email protected]>

Author: sean-madigan

subsys/bluetooth/controller/Kconfig

@@ -701,6 +701,16 @@ config BT_CTLR_SDC_LE_POWER_CLASS_1
 	  See Bluetooth Core Specification, Vol 6, Part A, Section 3
 	  Transmitter Characteristics for more information.
 
+config BT_CTLR_SDC_ENABLE_LOWEST_FRAME_SPACE
+	bool "Support lowest frame space values"
+	depends on BT_CTLR_FRAME_SPACE_UPDATE
+	default y
+	help
+	  Enabling this kconfig allows the controller to achieve the lowest
+	  possible frame spaces for ACLs.
+	  Note: This option forces ACL connections to always use the same
+	  TX and RX PHY.
+
 config BT_LL_SOFTDEVICE_INIT_PRIORITY
 	int
 	default 53 if MPSL_USE_EXTERNAL_CLOCK_CONTROL

subsys/bluetooth/controller/hci_driver.c

@@ -902,6 +902,9 @@ static void configure_supported_features(void)
 		if (IS_ENABLED(CONFIG_BT_PERIPHERAL)) {
 			sdc_support_frame_space_update_peripheral();
 		}
+		if (IS_ENABLED(CONFIG_BT_CTLR_SDC_ENABLE_LOWEST_FRAME_SPACE)) {
+			sdc_support_lowest_frame_space();
+		}
 	}
 
 	if (IS_ENABLED(CONFIG_BT_CTLR_SHORTER_CONNECTION_INTERVALS)) {