nimble/phy: Do not disable radio if TIFS is short

If TIFS is short then TX_TX and RX_RX transitions can be done
without disabling radio in between, just by triggering START.

Author: mkasenberg

nimble/drivers/nrf5x/src/ble_phy.c

@@ -920,6 +920,17 @@ ble_phy_get_ccm_datarate(void)
 }
 #endif
 
+static void
+ble_phy_end_handling_setup(void)
+{
+    if (g_ble_phy_data.tifs_usecs >= BLE_LL_IFS) {
+        NRF_RADIO->SHORTS |= RADIO_SHORTS_END_DISABLE_Msk;
+        nrf_radio_int_enable(NRF_RADIO, RADIO_INTENSET_DISABLED_Msk);
+    } else {
+        nrf_radio_int_enable(NRF_RADIO, RADIO_INTENSET_END_Msk);
+    }
+};
+
 /**
  * Setup transceiver for receive.
  */
@@ -969,6 +980,7 @@ ble_phy_rx_xcvr_setup(void)
 
     /* Turn off trigger TXEN on output compare match and AAR on bcmatch */
     phy_ppi_timer0_compare0_to_radio_txen_disable();
+    phy_ppi_timer0_compare0_to_radio_start_disable();
     phy_ppi_radio_bcmatch_to_aar_start_disable();
 
     /* Reset the rx started flag. Used for the wait for response */
@@ -997,14 +1009,11 @@ ble_phy_rx_xcvr_setup(void)
     NRF_RADIO->EVENTS_BCMATCH = 0;
     NRF_RADIO->EVENTS_RSSIEND = 0;
     NRF_RADIO->EVENTS_CRCOK = 0;
-    NRF_RADIO->SHORTS = RADIO_SHORTS_END_DISABLE_Msk |
-                        RADIO_SHORTS_READY_START_Msk |
+    NRF_RADIO->SHORTS = RADIO_SHORTS_READY_START_Msk |
                         RADIO_SHORTS_ADDRESS_BCSTART_Msk |
                         RADIO_SHORTS_ADDRESS_RSSISTART_Msk |
                         RADIO_SHORTS_DISABLED_RSSISTOP_Msk;
-
-    nrf_radio_int_enable(NRF_RADIO, RADIO_INTENSET_ADDRESS_Msk |
-                         RADIO_INTENSET_DISABLED_Msk);
+    nrf_radio_int_enable(NRF_RADIO, RADIO_INTENSET_ADDRESS_Msk);
 }
 
 static uint32_t
@@ -1047,6 +1056,11 @@ ble_transition_to_tx(uint8_t tifs_anchor, uint16_t tifs_usecs, uint8_t phy_state
     uint8_t next_phy_mode;
     uint8_t prev_phy_mode = g_ble_phy_data.phy_cur_phy_mode;
 
+    if (NRF_RADIO->STATE == RADIO_STATE_STATE_RxIdle) {
+        nrf_radio_task_trigger(NRF_RADIO, NRF_RADIO_TASK_DISABLE);
+        nrf_wait_disabled();
+    }
+
 #if MYNEWT_VAL(BLE_LL_PHY)
     ble_phy_mode_apply(g_ble_phy_data.phy_tx_phy_mode);
 #endif
@@ -1064,11 +1078,19 @@ ble_transition_to_tx(uint8_t tifs_anchor, uint16_t tifs_usecs, uint8_t phy_state
     phy_fem_enable_pa();
 #endif
 
-    /* Adjust for TX rump-up */
-    radio_time -= BLE_PHY_T_TXENFAST;
-    /* Adjust for delay between EVENT_READY and actual TX start time */
-    radio_time -= g_ble_phy_t_txdelay[next_phy_mode];
-    phy_ppi_timer0_compare0_to_radio_txen_enable();
+    if (NRF_RADIO->STATE == RADIO_STATE_STATE_Disabled) {
+        /* Adjust for TX rump-up */
+        radio_time -= BLE_PHY_T_TXENFAST;
+        /* Adjust for delay between EVENT_READY and actual TX start time */
+        radio_time -= g_ble_phy_t_txdelay[next_phy_mode];
+        phy_ppi_timer0_compare0_to_radio_txen_enable();
+    } else {
+        /* Fast TX_TX transition */
+        BLE_LL_ASSERT(NRF_RADIO->STATE == RADIO_STATE_STATE_TxIdle);
+        /* TODO: Adjust for delay between TASK_START and actual TX start time */
+        radio_time -= g_ble_phy_t_txdelay[next_phy_mode];
+        phy_ppi_timer0_compare0_to_radio_start_enable();
+    }
 
     nrf_timer_cc_set(NRF_TIMER0, 0, radio_time);
     NRF_TIMER0->EVENTS_COMPARE[0] = 0;
@@ -1101,6 +1123,11 @@ ble_transition_to_rx(uint8_t tifs_anchor, uint16_t tifs_usecs, uint8_t phy_state
     uint32_t radio_time;
     uint32_t start_time;
 
+    if (NRF_RADIO->STATE == RADIO_STATE_STATE_TxIdle) {
+        nrf_radio_task_trigger(NRF_RADIO, NRF_RADIO_TASK_DISABLE);
+        nrf_wait_disabled();
+    }
+
 #if MYNEWT_VAL(BLE_LL_PHY)
     ble_phy_mode_apply(g_ble_phy_data.phy_rx_phy_mode);
 #endif
@@ -1119,11 +1146,19 @@ ble_transition_to_rx(uint8_t tifs_anchor, uint16_t tifs_usecs, uint8_t phy_state
     phy_fem_enable_lna();
 #endif
 
-    /* Adjust for RX rump-up */
-    radio_time -= BLE_PHY_T_RXENFAST;
-    /* Start listening a bit earlier due to allowed active clock accuracy */
-    radio_time -= 2;
-    phy_ppi_timer0_compare0_to_radio_rxen_enable();
+    if (NRF_RADIO->STATE == RADIO_STATE_STATE_Disabled) {
+        /* Adjust for RX rump-up */
+        radio_time -= BLE_PHY_T_RXENFAST;
+        /* Start listening a bit earlier due to allowed active clock accuracy */
+        radio_time -= 2;
+        phy_ppi_timer0_compare0_to_radio_rxen_enable();
+    } else {
+        /* Fast RX_RX transition */
+        BLE_LL_ASSERT(NRF_RADIO->STATE == RADIO_STATE_STATE_RxIdle);
+        /* Start listening a bit earlier due to allowed active clock accuracy */
+        radio_time -= 2;
+        phy_ppi_timer0_compare0_to_radio_start_enable();
+    }
 
     /* Setup wfr relative to expected radio/PDU start */
     g_ble_phy_data.phy_start_time = start_time;
@@ -1148,6 +1183,7 @@ ble_transition_to_none(void)
     nrf_timer_task_trigger(NRF_TIMER0, NRF_TIMER_TASK_STOP);
     NRF_TIMER0->TASKS_SHUTDOWN = 1;
     phy_ppi_wfr_disable();
+    phy_ppi_timer0_compare0_to_radio_start_disable();
     phy_ppi_timer0_compare0_to_radio_txen_disable();
     phy_ppi_rtc0_compare0_to_timer0_start_disable();
     ble_phy_disable();
@@ -1164,7 +1200,9 @@ ble_phy_transition(uint8_t transition, uint8_t tifs_anchor, uint16_t tifs_usecs,
 {
     int rc = 1;
 
-    if (transition == PHY_TRANS_TO_TX) {
+    if (ble_ll_state_get() == BLE_LL_STATE_STANDBY) {
+        rc = 1;
+    } else if (transition == PHY_TRANS_TO_TX) {
         rc = ble_transition_to_tx(tifs_anchor, tifs_usecs, phy_state);
     } else if (transition == PHY_TRANS_TO_RX) {
         rc = ble_transition_to_rx(tifs_anchor, tifs_usecs, phy_state);
@@ -1224,8 +1262,12 @@ ble_phy_tx_end_isr(void)
 
     ble_phy_transition(transition, tifs_anchor, tifs_usecs, BLE_PHY_STATE_TX);
 
-    if (transition == BLE_PHY_TRANSITION_TO_RX) {
-        ble_phy_wfr_enable(BLE_PHY_WFR_ENABLE_TXRX, 0, g_ble_phy_data.wfr_usecs);
+    if (g_ble_phy_data.phy_state != BLE_PHY_STATE_IDLE) {
+        ble_phy_end_handling_setup();
+
+        if (transition == BLE_PHY_TRANSITION_TO_RX) {
+            ble_phy_wfr_enable(BLE_PHY_WFR_ENABLE_TXRX, 0, g_ble_phy_data.wfr_usecs);
+        }
     }
 }
 
@@ -1266,6 +1308,8 @@ ble_phy_rx_end_isr(void)
 
     /* Disable automatic RXEN */
     phy_ppi_timer0_compare0_to_radio_rxen_disable();
+    /* Disable automatic RX START */
+    phy_ppi_timer0_compare0_to_radio_start_disable();
 
     /* Set RSSI and CRC status flag in header */
     ble_hdr = &g_ble_phy_data.rxhdr;
@@ -1349,8 +1393,12 @@ ble_phy_rx_end_isr(void)
         return;
     }
 
-    if (transition == BLE_PHY_TRANSITION_TO_RX) {
-        ble_phy_wfr_enable(BLE_PHY_WFR_ENABLE_RXRX, 0, g_ble_phy_data.wfr_usecs);
+    if (g_ble_phy_data.phy_state != BLE_PHY_STATE_IDLE) {
+        ble_phy_end_handling_setup();
+
+        if (transition == BLE_PHY_TRANSITION_TO_RX) {
+            ble_phy_wfr_enable(BLE_PHY_WFR_ENABLE_RXRX, 0, g_ble_phy_data.wfr_usecs);
+        }
     }
 }
 
@@ -1519,13 +1567,15 @@ ble_phy_isr(void)
      * need to check phy_rx_started flag to make sure we actually were receiving
      * a PDU, otherwise this is due to wfr.
      */
-    if ((irq_en & RADIO_INTENCLR_DISABLED_Msk) && NRF_RADIO->EVENTS_DISABLED) {
+    if (((irq_en & RADIO_INTENCLR_DISABLED_Msk) && NRF_RADIO->EVENTS_DISABLED) ||
+        ((irq_en & RADIO_INTENCLR_END_Msk) && NRF_RADIO->EVENTS_END)) {
+
         BLE_LL_ASSERT(NRF_RADIO->EVENTS_END ||
                       ((g_ble_phy_data.phy_state == BLE_PHY_STATE_RX) &&
                        !g_ble_phy_data.phy_rx_started));
         NRF_RADIO->EVENTS_END = 0;
         NRF_RADIO->EVENTS_DISABLED = 0;
-        nrf_radio_int_disable(NRF_RADIO, RADIO_INTENCLR_DISABLED_Msk);
+        nrf_radio_int_disable(NRF_RADIO, RADIO_INTENCLR_DISABLED_Msk | RADIO_INTENCLR_END_Msk);
 
         switch (g_ble_phy_data.phy_state) {
         case BLE_PHY_STATE_RX:
@@ -1755,6 +1805,8 @@ ble_phy_rx(void)
     /* Setup for rx */
     ble_phy_rx_xcvr_setup();
 
+    ble_phy_end_handling_setup();
+
     return 0;
 }
 
@@ -1849,6 +1901,7 @@ ble_phy_tx_set_start_time(uint32_t cputime, uint8_t rem_usecs)
     /* XXX: This should not be necessary, but paranoia is good! */
     /* Clear timer0 compare to RXEN since we are transmitting */
     phy_ppi_timer0_compare0_to_radio_rxen_disable();
+    phy_ppi_timer0_compare0_to_radio_start_disable();
 
     if (ble_phy_set_start_time(cputime, rem_usecs, true) != 0) {
         STATS_INC(ble_phy_stats, tx_late);
@@ -1891,6 +1944,7 @@ ble_phy_rx_set_start_time(uint32_t cputime, uint8_t rem_usecs)
     /* XXX: This should not be necessary, but paranoia is good! */
     /* Clear timer0 compare to TXEN since we are transmitting */
     phy_ppi_timer0_compare0_to_radio_txen_disable();
+    phy_ppi_timer0_compare0_to_radio_start_disable();
 
     if (ble_phy_set_start_time(cputime, rem_usecs, false) != 0) {
         STATS_INC(ble_phy_stats, rx_late);
@@ -1927,7 +1981,6 @@ ble_phy_tx(ble_phy_tx_pducb_t pducb, void *pducb_arg)
     uint8_t payload_len;
     uint8_t hdr_byte;
     uint32_t state;
-    uint32_t shortcuts;
     uint8_t end_trans;
 
     if (g_ble_phy_data.phy_transition_late) {
@@ -2010,9 +2063,8 @@ ble_phy_tx(ble_phy_tx_pducb_t pducb, void *pducb_arg)
     NRF_RADIO->EVENTS_DISABLED = 0;
 
     /* Enable shortcuts for transmit start/end. */
-    shortcuts = RADIO_SHORTS_END_DISABLE_Msk | RADIO_SHORTS_READY_START_Msk;
-    NRF_RADIO->SHORTS = shortcuts;
-    nrf_radio_int_enable(NRF_RADIO, RADIO_INTENSET_DISABLED_Msk);
+    NRF_RADIO->SHORTS = RADIO_SHORTS_READY_START_Msk;
+    ble_phy_end_handling_setup();
 
     /* Set the PHY transition */
     g_ble_phy_data.phy_transition = end_trans;

nimble/drivers/nrf5x/src/nrf52/phy.c

@@ -169,14 +169,18 @@ phy_ppi_init(void)
      * Channel 4: Captures TIMER0 in CC[3] when EVENTS_ADDRESS occurs. Used
      *            to cancel the wait for response timer.
      * Channel 5: TIMER0 CC[3] to TASKS_DISABLE on radio. This is the wait
-     *            for response timer.
+     *            for response timer (or measurement timer)
+     * Channel 8: TIMER0 CC[0] to TASKS_START on radio.
      */
     nrf_ppi_channel_endpoint_setup(NRF_PPI, NRF_PPI_CHANNEL4,
                                    (uint32_t)&(NRF_RADIO->EVENTS_ADDRESS),
                                    (uint32_t)&(NRF_TIMER0->TASKS_CAPTURE[3]));
     nrf_ppi_channel_endpoint_setup(NRF_PPI, NRF_PPI_CHANNEL5,
                                    (uint32_t)&(NRF_TIMER0->EVENTS_COMPARE[3]),
                                    (uint32_t)&(NRF_RADIO->TASKS_DISABLE));
+    nrf_ppi_channel_endpoint_setup(NRF_PPI, NRF_PPI_CHANNEL8,
+                                   (uint32_t)&(NRF_TIMER0->EVENTS_COMPARE[0]),
+                                   (uint32_t)&(NRF_RADIO->TASKS_START));
 }
 
 void

nimble/drivers/nrf5x/src/nrf52/phy_ppi.h

@@ -58,6 +58,18 @@ phy_ppi_timer0_compare0_to_radio_rxen_disable(void)
     nrf_ppi_channels_disable(NRF_PPI, PPI_CHEN_CH21_Msk);
 }
 
+static inline void
+phy_ppi_timer0_compare0_to_radio_start_enable(void)
+{
+    nrf_ppi_channels_enable(NRF_PPI, PPI_CHEN_CH8_Msk);
+}
+
+static inline void
+phy_ppi_timer0_compare0_to_radio_start_disable(void)
+{
+    nrf_ppi_channels_disable(NRF_PPI, PPI_CHEN_CH8_Msk);
+}
+
 static inline void
 phy_ppi_radio_bcmatch_to_aar_start_enable(void)
 {
@@ -105,6 +117,7 @@ phy_ppi_disable(void)
 {
     nrf_ppi_channels_disable(NRF_PPI, PPI_CHEN_CH4_Msk | PPI_CHEN_CH5_Msk |
                                       PPI_CHEN_CH6_Msk | PPI_CHEN_CH7_Msk |
+                                      PPI_CHEN_CH8_Msk |
                                       PPI_CHEN_CH20_Msk | PPI_CHEN_CH21_Msk |
                                       PPI_CHEN_CH23_Msk | PPI_CHEN_CH25_Msk |
                                       PPI_CHEN_CH31_Msk);

nimble/drivers/nrf5x/src/nrf53/phy_ppi.h

@@ -86,6 +86,18 @@ phy_ppi_timer0_compare0_to_radio_rxen_disable(void)
     NRF_RADIO->SUBSCRIBE_RXEN = DPPI_CH_UNSUB(TIMER0_EVENTS_COMPARE_0);
 }
 
+static inline void
+phy_ppi_timer0_compare0_to_radio_start_enable(void)
+{
+    NRF_RADIO->SUBSCRIBE_START = DPPI_CH_SUB(TIMER0_EVENTS_COMPARE_0);
+}
+
+static inline void
+phy_ppi_timer0_compare0_to_radio_start_disable(void)
+{
+    NRF_RADIO->SUBSCRIBE_START = DPPI_CH_UNSUB(TIMER0_EVENTS_COMPARE_0);
+}
+
 static inline void
 phy_ppi_radio_address_to_ccm_crypt_enable(void)
 {