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Improve Bluetooth credit handling and Switch 2 connection timing

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This commit is contained in:
Joey Yakimowich-Payne 2026-09-09 10:40:25 -06:00
commit 7c1c37a84e
13 changed files with 408 additions and 71 deletions
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159
patches/btstack-credit-batch.patch
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@ -1,6 +1,6 @@
--- a/lib/btstack/src/hci.c
+++ b/lib/btstack/src/hci.c
@@ -93,6 +93,12 @@
@@ -93,6 +93,20 @@
#endif
#endif
@ -9,11 +9,19 @@
+#error "SWITCH_PICO_HCI_CREDIT_BATCH requires controller-to-host flow control with three ACL credits"
+#endif
+#endif
+#ifdef SWITCH_PICO_HCI_CREDIT_BUFFER
+#ifndef SWITCH_PICO_HCI_CREDIT_BATCH
+#error "SWITCH_PICO_HCI_CREDIT_BUFFER requires SWITCH_PICO_HCI_CREDIT_BATCH"
+#endif
+#if !defined(MAX_NR_HCI_CONNECTIONS) || (MAX_NR_HCI_CONNECTIONS < 1) || (MAX_NR_HCI_CONNECTIONS > 63)
+#error "SWITCH_PICO_HCI_CREDIT_BUFFER requires 1..63 configured HCI connections"
+#endif
+#endif
+
#ifndef MAX_NR_CONTROLLER_ACL_BUFFERS
#define MAX_NR_CONTROLLER_ACL_BUFFERS 255
#endif
@@ -273,6 +279,74 @@
@@ -273,6 +287,84 @@
#endif
static hci_stack_t * hci_stack = NULL;
@ -23,6 +31,13 @@
+static bool hci_credit_batch_due;
+static bool hci_credit_batch_enabled;
+static uint32_t hci_credit_batch_generation;
+#ifdef SWITCH_PICO_HCI_CREDIT_BUFFER
+static bool hci_credit_batch_in_flight;
+// Independent of the prepared ACL buffer, including transport header and word padding.
+#define HCI_CREDIT_BATCH_PRE_BUFFER_SIZE ((HCI_OUTGOING_PRE_BUFFER_SIZE + 3u) & ~3u)
+static uint32_t hci_credit_batch_buffer[
+ (HCI_CREDIT_BATCH_PRE_BUFFER_SIZE + 4u + 4u * MAX_NR_HCI_CONNECTIONS) / sizeof(uint32_t)];
+#endif
+
+static void hci_credit_batch_reset(void){
+ if (hci_credit_batch_armed){
@ -34,7 +49,10 @@
+
+static void hci_credit_batch_stop(void){
+ hci_credit_batch_enabled = false;
+#ifndef SWITCH_PICO_HCI_CREDIT_BUFFER
+ hci_credit_batch_generation++;
+#endif
+ // Cancellation does not end an asynchronous transfer; completion or close does.
+ hci_credit_batch_reset();
+}
+
@ -88,7 +106,27 @@
#ifdef ENABLE_CLASSIC
// default name
static const char * default_classic_name = "BTstack 00:00:00:00:00:00";
@@ -1195,6 +1269,9 @@
@@ -738,6 +830,9 @@
// only used to send HCI Host Number Completed Packets
static int hci_can_send_command_packet_transport(void){
+#ifdef SWITCH_PICO_HCI_CREDIT_BUFFER
+ if (hci_credit_batch_in_flight) return 0;
+#endif
if (hci_stack->hci_packet_buffer_reserved) return 0;
// check for async hci transport implementations
@@ -756,6 +851,9 @@
}
static int hci_transport_can_send_prepared_packet_now(uint8_t packet_type){
+#ifdef SWITCH_PICO_HCI_CREDIT_BUFFER
+ if (hci_credit_batch_in_flight) return false;
+#endif
// check for async hci transport implementations
if (!hci_stack->hci_transport->can_send_packet_now) return true;
return hci_stack->hci_transport->can_send_packet_now(packet_type);
@@ -1195,6 +1293,9 @@
#ifdef ENABLE_HCI_CONTROLLER_TO_HOST_FLOW_CONTROL
hci_stack->host_completed_packets = 1;
conn->num_packets_completed++;
@ -98,7 +136,7 @@
#endif
// handle different packet types
@@ -1269,8 +1346,10 @@
@@ -1269,8 +1370,10 @@
return;
}
@ -109,7 +147,7 @@
}
static void hci_connection_stop_timer(hci_connection_t * conn){
@@ -1296,6 +1375,9 @@
@@ -1296,6 +1399,9 @@
btstack_linked_list_remove(&hci_stack->connections, (btstack_linked_item_t *) conn);
btstack_memory_hci_connection_free( conn );
@ -119,7 +157,7 @@
// now it's gone
hci_emit_nr_connections_changed();
@@ -4314,6 +4396,12 @@
@@ -4314,6 +4420,12 @@
conn = hci_connection_for_handle(handle);
if (!conn) break;
@ -132,7 +170,21 @@
#ifdef ENABLE_CLASSIC
// pairing failed if it was ongoing
hci_pairing_complete(conn, ERROR_CODE_REMOTE_USER_TERMINATED_CONNECTION);
@@ -4780,6 +4868,10 @@
@@ -4367,6 +4479,13 @@
log_error("Synchronous HCI Transport shouldn't send HCI_EVENT_TRANSPORT_PACKET_SENT");
return; // instead of break: to avoid re-entering hci_run()
}
+#ifdef SWITCH_PICO_HCI_CREDIT_BUFFER
+ if (hci_credit_batch_in_flight){
+ hci_credit_batch_in_flight = false;
+ // This completion owns only the credit buffer, not a prepared ACL fragment.
+ break;
+ }
+#endif
hci_stack->acl_fragmentation_tx_active = 0;
#ifdef ENABLE_LE_ISOCHRONOUS_STREAMS
hci_stack->iso_fragmentation_tx_active = 0;
@@ -4780,6 +4899,10 @@
#ifdef ENABLE_HCI_CONTROLLER_TO_HOST_FLOW_CONTROL
conn->num_packets_completed++;
hci_stack->host_completed_packets = 1;
@ -143,7 +195,7 @@
hci_run();
#endif
}
@@ -4814,6 +4906,10 @@
@@ -4814,6 +4937,10 @@
break;
case HCI_ACL_DATA_PACKET:
acl_handler(packet, size);
@ -154,19 +206,22 @@
break;
#ifdef ENABLE_CLASSIC
case HCI_SCO_DATA_PACKET:
@@ -4869,6 +4965,11 @@
@@ -4869,6 +4996,14 @@
#endif
static void hci_state_reset(void){
+#ifdef SWITCH_PICO_HCI_CREDIT_BATCH
+ hci_credit_batch_reset();
+ hci_credit_batch_generation++;
+#ifdef SWITCH_PICO_HCI_CREDIT_BUFFER
+ hci_credit_batch_in_flight = false;
+#endif
+ hci_stack->host_completed_packets = 0;
+#endif
// no connections yet
hci_stack->connections = NULL;
@@ -4953,6 +5054,10 @@
@@ -4953,6 +5088,10 @@
#endif
void hci_init(const hci_transport_t *transport, const void *config){
@ -177,7 +232,7 @@
#ifdef HAVE_MALLOC
if (!hci_stack) {
@@ -5082,6 +5187,9 @@
@@ -5082,6 +5221,9 @@
}
void hci_deinit(void){
@ -187,7 +242,7 @@
btstack_run_loop_remove_timer(&hci_stack->timeout);
#ifdef HAVE_MALLOC
if (hci_stack) {
@@ -5138,6 +5246,9 @@
@@ -5138,6 +5280,9 @@
}
void hci_close(void){
@ -197,7 +252,7 @@
#ifdef ENABLE_CLASSIC
// close remote device db
@@ -5264,6 +5375,10 @@
@@ -5264,6 +5409,10 @@
// HCI_STATE_FALLING_ASLEEP on open
static int hci_power_control_on(void){
@ -208,7 +263,7 @@
// power on
int err = 0;
@@ -5300,6 +5415,9 @@
@@ -5300,11 +5449,18 @@
}
static void hci_power_control_off(void){
@ -218,7 +273,16 @@
log_info("hci_power_control_off");
@@ -5319,6 +5437,9 @@
// close low-level device
hci_stack->hci_transport->close();
+#ifdef SWITCH_PICO_HCI_CREDIT_BUFFER
+ hci_credit_batch_in_flight = false;
+ hci_credit_batch_generation++;
+#endif
log_info("hci_power_control_off - hci_transport closed");
@@ -5319,6 +5475,9 @@
}
static void hci_power_control_sleep(void){
@ -228,7 +292,7 @@
log_info("hci_power_control_sleep");
@@ -5363,6 +5484,10 @@
@@ -5363,6 +5522,10 @@
}
static void hci_power_enter_initializing_state(void){
@ -239,7 +303,7 @@
// set up state machine
hci_stack->num_cmd_packets = 1; // assume that one cmd can be sent
hci_stack->hci_packet_buffer_reserved = false;
@@ -5543,6 +5668,10 @@
@@ -5543,6 +5706,10 @@
}
int hci_power_control(HCI_POWER_MODE power_mode){
@ -250,7 +314,7 @@
log_info("hci_power_control: %d, current mode %u", power_mode, hci_stack->state);
btstack_run_loop_remove_timer(&hci_stack->timeout);
int err = 0;
@@ -5834,6 +5963,11 @@
@@ -5834,10 +6001,19 @@
#ifdef ENABLE_HCI_CONTROLLER_TO_HOST_FLOW_CONTROL
static void hci_host_num_completed_packets(void){
@ -261,9 +325,32 @@
+#endif
// create packet manually as arrays are not supported and num_commands should not get reduced
+#ifdef SWITCH_PICO_HCI_CREDIT_BUFFER
+ uint8_t * packet = (uint8_t *) hci_credit_batch_buffer + HCI_CREDIT_BATCH_PRE_BUFFER_SIZE;
+#else
hci_reserve_packet_buffer();
@@ -5868,6 +6002,9 @@
uint8_t * packet = hci_get_outgoing_packet_buffer();
+#endif
uint16_t size = 0;
uint16_t num_handles = 0;
@@ -5851,6 +6027,9 @@
for (it = (btstack_linked_item_t *) hci_stack->connections; it ; it = it->next){
hci_connection_t * connection = (hci_connection_t *) it;
if (connection->num_packets_completed){
+#ifdef SWITCH_PICO_HCI_CREDIT_BUFFER
+ btstack_assert(num_handles < MAX_NR_HCI_CONNECTIONS);
+#endif
little_endian_store_16(packet, size, connection->con_handle);
size += 2;
little_endian_store_16(packet, size, connection->num_packets_completed);
@@ -5866,12 +6045,22 @@
hci_stack->host_completed_packets = 0;
+#ifdef SWITCH_PICO_HCI_CREDIT_BUFFER
+ hci_credit_batch_in_flight = true;
+#endif
hci_dump_packet(HCI_COMMAND_DATA_PACKET, 0, packet, size);
hci_stack->hci_transport->send_packet(HCI_COMMAND_DATA_PACKET, packet, size);
+#ifdef SWITCH_PICO_HCI_CREDIT_BATCH
@ -272,10 +359,41 @@
// release packet buffer for synchronous transport implementations
if (hci_transport_synchronous()){
@@ -7664,12 +7801,21 @@
+#ifdef SWITCH_PICO_HCI_CREDIT_BUFFER
+ hci_credit_batch_in_flight = false;
+#else
hci_release_packet_buffer();
+#endif
hci_emit_transport_packet_sent();
}
}
@@ -7652,6 +7841,21 @@
return;
}
+#ifdef SWITCH_PICO_HCI_CREDIT_BUFFER
+ if (hci_credit_batch_in_flight) return;
+ // Return receive credits before continuing an ACL packet that may exhaust
+ // transmit credits. A prepared packet is not an occupied transport.
+ if (hci_stack->host_completed_packets && hci_credit_batch_ready()){
+ if (!hci_transport_synchronous() && hci_stack->acl_fragmentation_tx_active) return;
+#ifdef ENABLE_LE_ISOCHRONOUS_STREAMS
+ if (hci_stack->iso_fragmentation_tx_active) return;
+#endif
+ if (!hci_transport_can_send_prepared_packet_now(HCI_COMMAND_DATA_PACKET)) return;
+ hci_host_num_completed_packets();
+ return;
+ }
+#endif
+
bool done;
// send continuation fragments first, as they block the prepared packet buffer
@@ -7664,12 +7868,23 @@
#endif
#ifdef ENABLE_HCI_CONTROLLER_TO_HOST_FLOW_CONTROL
+#ifndef SWITCH_PICO_HCI_CREDIT_BUFFER
+#ifdef SWITCH_PICO_HCI_CREDIT_BATCH
+ // A single deferred ACL credit must not block ordinary HCI commands.
+ if (hci_stack->host_completed_packets && hci_credit_batch_ready()){
@ -290,6 +408,7 @@
hci_host_num_completed_packets();
return;
}
+#endif
+#endif
#endif