Bluetooth: controller: llcp: serialize phy update notifications

The PHY update procedure may trigger a DLE update in certain
situations
When a limited number of rx buffers is available there may not be
enough for doing the phy update and dle update notifications
at once.

Fixes #41788

Signed-off-by: Andries Kruithof <Andries.Kruithof@nordicsemi.no>

subsys/bluetooth/controller/ll_sw/ull_llcp_phy.c

@@ -260,10 +260,10 @@ static uint8_t pu_update_eff_times(struct ll_conn *conn, struct proc_ctx *ctx)
 	    (eff_rx_time != lll->dle.eff.max_rx_time)) {
 		lll->dle.eff.max_tx_time = eff_tx_time;
 		lll->dle.eff.max_rx_time = eff_rx_time;
-		return 1;
+		return 1U;
 	}
 
-	return 0;
+	return 0U;
 }
 #endif /* CONFIG_BT_CTLR_DATA_LENGTH */
 
@@ -366,6 +366,7 @@ static void pu_ntf(struct ll_conn *conn, struct proc_ctx *ctx)
 	/* Enqueue notification towards LL */
 	ll_rx_put(ntf->hdr.link, ntf);
 	ll_rx_sched();
+	ctx->data.pu.ntf_pu = 0;
 }
 
 #if defined(CONFIG_BT_CTLR_DATA_LENGTH)
@@ -397,17 +398,33 @@ static void lp_pu_complete(struct ll_conn *conn, struct proc_ctx *ctx, uint8_t e
 #else
 #define NTF_DLE 0
 #endif
-	const uint8_t ntf_count = ctx->data.pu.ntf_pu + NTF_DLE;
+	uint8_t ntf_count = ctx->data.pu.ntf_pu + NTF_DLE;
 	/* when complete reset timing restrictions - idempotent
 	 * (so no problem if we need to wait for NTF buffer)
 	 */
+
 	pu_reset_timing_restrict(conn);
 
+	/* if we need to send both PHY and DLE notification, but we
+	 * do not have 2 buffers available we serialize the sending
+	 * of notifications
+	 */
+#if defined(CONFIG_BT_CTLR_DATA_LENGTH)
+	if ((ntf_count > 1) && !llcp_ntf_alloc_num_available(ntf_count)) {
+		ntf_count = 1;
+	}
+#endif /* CONFIG_BT_CTLR_DATA_LENGTH */
 	if (ntf_count && !llcp_ntf_alloc_num_available(ntf_count)) {
 		ctx->state = LP_PU_STATE_WAIT_NTF;
 	} else {
 		if (ctx->data.pu.ntf_pu) {
 			pu_ntf(conn, ctx);
+#if defined(CONFIG_BT_CTLR_DATA_LENGTH)
+			if (ntf_count == 1 && NTF_DLE == 1) {
+				ctx->state = LP_PU_STATE_WAIT_NTF;
+				return;
+			}
+#endif /* CONFIG_BT_CTLR_DATA_LENGTH */
 		}
 #if defined(CONFIG_BT_CTLR_DATA_LENGTH)
 		if (ctx->data.pu.ntf_dle) {
@@ -796,17 +813,32 @@ static void rp_pu_complete(struct ll_conn *conn, struct proc_ctx *ctx, uint8_t e
 #else
 #define NTF_DLE 0
 #endif
-	const uint8_t ntf_count = ctx->data.pu.ntf_pu + NTF_DLE;
+	uint8_t ntf_count = ctx->data.pu.ntf_pu + NTF_DLE;
 	/* when complete reset timing restrictions - idempotent
 	 * (so no problem if we need to wait for NTF buffer)
 	 */
 	pu_reset_timing_restrict(conn);
 
+	/* if we need to send both PHY and DLE notification, but we
+	 * do not have 2 buffers available we serialize the sending
+	 * of notifications
+	 */
+#if defined(CONFIG_BT_CTLR_DATA_LENGTH)
+	if ((ntf_count > 1) && !llcp_ntf_alloc_num_available(ntf_count)) {
+		ntf_count = 1;
+	}
+#endif /* CONFIG_BT_CTLR_DATA_LENGTH) */
 	if ((ntf_count > 0) && !llcp_ntf_alloc_num_available(ntf_count)) {
 		ctx->state = RP_PU_STATE_WAIT_NTF;
 	} else {
 		if (ctx->data.pu.ntf_pu) {
 			pu_ntf(conn, ctx);
+#if defined(CONFIG_BT_CTLR_DATA_LENGTH)
+			if (ntf_count == 1 && NTF_DLE == 1) {
+				ctx->state = RP_PU_STATE_WAIT_NTF;
+				return;
+			}
+#endif /* CONFIG_BT_CTLR_DATA_LENGTH */
 		}
 #if defined(CONFIG_BT_CTLR_DATA_LENGTH)
 		if (ctx->data.pu.ntf_dle) {

tests/bluetooth/controller/ctrl_phy_update/src/kconfig_override_rx_cnt.h

@@ -0,0 +1,11 @@
+/*
+ * Copyright (c) 2021 Demant
+ * Copyright (c) 2021 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+#ifdef CONFIG_BT_CTLR_LLCP_CONN
+#undef CONFIG_BT_CTLR_LLCP_CONN
+#define CONFIG_BT_CTLR_LLCP_CONN 2
+#endif

tests/bluetooth/controller/ctrl_phy_update/testcase.yaml

@@ -3,3 +3,6 @@ common:
 tests:
   bluetooth.controller.ctrl_phy_update.test:
      type: unit
+  bluetooth.controller.ctrl_phy_update.test_reduced_buf:
+     type: unit
+     extra_args: KCONFIG_OVERRIDE_FILE="kconfig_override_rx_cnt.h"

tests/bluetooth/controller/mock_ctrl/include/kconfig.h

@@ -79,7 +79,9 @@
 #define CONFIG_BT_CTLR_XTAL_ADVANCED y
 #endif
 
+#ifndef CONFIG_BT_CTLR_LLCP_CONN
 #define CONFIG_BT_CTLR_LLCP_CONN 4
+#endif
 
 #ifndef CONFIG_BT_CTLR_LLCP_TX_PER_CONN_TX_CTRL_BUF_NUM_MAX
 #define CONFIG_BT_CTLR_LLCP_TX_PER_CONN_TX_CTRL_BUF_NUM_MAX (4)