pbio/os: Don't poll on single yield.

Awaiting once is sometimes useful with a poll, but not always.

Make the macro more general purpose by doing it explicitly, only when needed.

Author: laurensvalk

lib/pbio/drv/charger/charger_mp2639a.c

@@ -187,13 +187,15 @@ pbio_error_t pbdrv_charger_mp2639a_process_thread(pbio_os_state_t *state, void *
 
     #if PBDRV_CONFIG_CHARGER_MP2639A_MODE_PWM
     while (pbdrv_pwm_get_dev(platform.mode_pwm_id, &mode_pwm) != PBIO_SUCCESS) {
-        PBIO_OS_AWAIT_ONCE_AND_POLL(state);
+        pbio_os_request_poll();
+        PBIO_OS_AWAIT_ONCE(state);
     }
     #endif
 
     #if PBDRV_CONFIG_CHARGER_MP2639A_ISET_PWM
     while (pbdrv_pwm_get_dev(platform.iset_pwm_id, &iset_pwm) != PBIO_SUCCESS) {
-        PBIO_OS_AWAIT_ONCE_AND_POLL(state);
+        pbio_os_request_poll();
+        PBIO_OS_AWAIT_ONCE(state);
     }
     #endif
 

lib/pbio/drv/pwm/pwm_lp50xx_stm32.c

@@ -123,7 +123,8 @@ static pbio_error_t pbdrv_pwm_lp50xx_stm32_process_thread(pbio_os_state_t *state
     PBIO_OS_ASYNC_BEGIN(state);
 
     // Need to allow all drivers to init first.
-    PBIO_OS_AWAIT_ONCE_AND_POLL(state);
+    pbio_os_request_poll();
+    PBIO_OS_AWAIT_ONCE(state);
 
     static const struct {
         uint8_t reg;

lib/pbio/drv/uart/uart_debug_first_port.c

@@ -90,7 +90,8 @@ static pbio_error_t pbdrv_uart_debug_process_thread(pbio_os_state_t *state, void
     PBIO_OS_ASYNC_BEGIN(state);
 
     while (pbdrv_uart_get_instance(0, &debug_uart) != PBIO_SUCCESS) {
-        PBIO_OS_AWAIT_ONCE_AND_POLL(state);
+        pbio_os_request_poll();
+        PBIO_OS_AWAIT_ONCE(state);
     }
 
     pbdrv_uart_set_baud_rate(debug_uart, 115200);

lib/pbio/include/pbio/os.h

@@ -253,25 +253,15 @@ struct _pbio_os_process_t {
     } while (0)
 
 /**
- * Yields the protothread here once and polls to request handling again
- * immediately.
- *
- * Can be useful if several protothreads are started at the same time but not
- * in any particular order. PBIO_OS_AWAIT_ONCE_AND_POLL can be used in a loop
- * until the other protothreads have finished initializing as defined by
- * mutually defined state variables.
- *
- * Should be used sparingly as it can cause busy waiting. Processes will keep
- * running, but there will always be another event pending after this is used.
+ * Yields the protothread here once.
  *
  * @param [in]  state     Protothread state.
  */
-#define PBIO_OS_AWAIT_ONCE_AND_POLL(state)      \
+#define PBIO_OS_AWAIT_ONCE(state)               \
     do {                                        \
         do_yield_now = 1;                       \
         PBIO_OS_ASYNC_SET_CHECKPOINT(state);    \
         if (do_yield_now) {                     \
-            pbio_os_request_poll();             \
             return PBIO_ERROR_AGAIN;            \
         }                                       \
     } while (0)