extmod/nimble: Make stm32 and unix NimBLE ports use synchronous events.

This changes stm32 from using PENDSV to run NimBLE to use the MicroPython
scheduler instead.  This allows Python BLE callbacks to be invoked directly
(and therefore synchronously) rather than via the ringbuffer.

The NimBLE UART HCI and event processing now happens in a scheduled task
every 128ms.  When RX IRQ idle events arrive, it will also schedule this
task to improve latency.

There is a similar change for the unix port where the background thread now
queues the scheduled task.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

1 files changed, 17 insertions, 6 deletions

diff --git a/extmod/nimble/hal/hal_uart.c b/extmod/nimble/hal/hal_uart.c
index c6d0850fe..230970b08 100644
--- a/extmod/nimble/hal/hal_uart.c
+++ b/extmod/nimble/hal/hal_uart.c
@@ -28,10 +28,13 @@
 #include "py/mphal.h"
 #include "nimble/ble.h"
 #include "extmod/nimble/hal/hal_uart.h"
+#include "extmod/nimble/nimble/nimble_npl_os.h"
 #include "extmod/mpbthci.h"
 
 #if MICROPY_PY_BLUETOOTH && MICROPY_BLUETOOTH_NIMBLE
 
+#define HCI_TRACE (0)
+
 static hal_uart_tx_cb_t hal_uart_tx_cb;
 static void *hal_uart_tx_arg;
 static hal_uart_rx_cb_t hal_uart_rx_cb;
@@ -62,10 +65,10 @@ void hal_uart_start_tx(uint32_t port) {
         mp_bluetooth_hci_cmd_buf[len++] = data;
     }
 
-    #if 0
-    printf("[% 8d] BTUTX: %02x", mp_hal_ticks_ms(), hci_cmd_buf[0]);
-    for (int i = 1; i < len; ++i) {
-        printf(":%02x", hci_cmd_buf[i]);
+    #if HCI_TRACE
+    printf("< [% 8d] %02x", mp_hal_ticks_ms(), mp_bluetooth_hci_cmd_buf[0]);
+    for (size_t i = 1; i < len; ++i) {
+        printf(":%02x", mp_bluetooth_hci_cmd_buf[i]);
     }
     printf("\n");
     #endif
@@ -77,13 +80,21 @@ int hal_uart_close(uint32_t port) {
     return 0; // success
 }
 
-void mp_bluetooth_nimble_hci_uart_process(void) {
+void mp_bluetooth_nimble_hci_uart_process(bool run_events) {
     bool host_wake = mp_bluetooth_hci_controller_woken();
 
     int chr;
     while ((chr = mp_bluetooth_hci_uart_readchar()) >= 0) {
-        // printf("UART RX: %02x\n", data);
+        #if HCI_TRACE
+        printf("> %02x (%d)\n", chr);
+        #endif
         hal_uart_rx_cb(hal_uart_rx_arg, chr);
+
+        // Incoming data may result in events being enqueued. If we're in
+        // scheduler context then we can run those events immediately.
+        if (run_events) {
+            mp_bluetooth_nimble_os_eventq_run_all();
+        }
     }
 
     if (host_wake) {