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Bluetooth: Controller: Fix sw switch single timer for spurious TXEN/RXEN

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Fix software tIFS switching using single timer from
triggering spurious TXEN/RXEN if the first remainder is
shorter than the tIFS delay calculated in the sw_switch()
function.

Signed-off-by: Vinayak Kariappa Chettimada <vich@nordicsemi.no>
This commit is contained in:
Vinayak Kariappa Chettimada 2024-07-06 02:21:13 +02:00 • committed by Anas Nashif
commit bcd28e0a86
3 changed files with 68 additions and 4 deletions
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56
subsys/bluetooth/controller/ll_sw/nordic/hal/nrf5/radio/radio.c
View file

@ -1337,6 +1337,21 @@ uint32_t radio_tmr_start(uint8_t trx, uint32_t ticks_start, uint32_t remainder)
{
hal_ticker_remove_jitter(&ticks_start, &remainder);
#if defined(CONFIG_BT_CTLR_SW_SWITCH_SINGLE_TIMER)
/* When using single timer for software tIFS switching, ensure that
* the timer compare value is large enough to consider radio ISR
* latency so that the ISR is able to disable the PPI/DPPI that again
* could trigger the TXEN/RXEN task.
* The timer is cleared on Radio End and if the PPI/DPPI is not disabled
* by the Radio ISR, the compare will trigger again.
*/
uint32_t latency_ticks;
latency_ticks = HAL_TICKER_US_TO_TICKS(HAL_RADIO_ISR_LATENCY_MAX_US);
ticks_start -= latency_ticks;
remainder += HAL_TICKER_TICKS_TO_US(latency_ticks);
#endif /* !CONFIG_BT_CTLR_SW_SWITCH_SINGLE_TIMER */
nrf_timer_task_trigger(EVENT_TIMER, NRF_TIMER_TASK_CLEAR);
EVENT_TIMER->MODE = 0;
EVENT_TIMER->PRESCALER = HAL_EVENT_TIMER_PRESCALER_VALUE;
@ -1388,11 +1403,27 @@ uint32_t radio_tmr_start_tick(uint8_t trx, uint32_t tick)
{
uint32_t remainder_us;
/* Setup compare event with min. 1 us offset */
remainder_us = 1;
#if defined(CONFIG_BT_CTLR_SW_SWITCH_SINGLE_TIMER)
/* When using single timer for software tIFS switching, ensure that
* the timer compare value is large enough to consider radio ISR
* latency so that the ISR is able to disable the PPI/DPPI that again
* could trigger the TXEN/RXEN task.
* The timer is cleared on Radio End and if the PPI/DPPI is not disabled
* by the Radio ISR, the compare will trigger again.
*/
uint32_t latency_ticks;
latency_ticks = HAL_TICKER_US_TO_TICKS(HAL_RADIO_ISR_LATENCY_MAX_US);
ticks_start -= latency_ticks;
remainder_us += HAL_TICKER_TICKS_TO_US(latency_ticks);
#endif /* !CONFIG_BT_CTLR_SW_SWITCH_SINGLE_TIMER */
nrf_timer_task_trigger(EVENT_TIMER, NRF_TIMER_TASK_STOP);
nrf_timer_task_trigger(EVENT_TIMER, NRF_TIMER_TASK_CLEAR);
/* Setup compare event with min. 1 us offset */
remainder_us = 1;
nrf_timer_cc_set(EVENT_TIMER, 0, remainder_us);
nrf_rtc_cc_set(NRF_RTC, 2, tick);
@ -1452,6 +1483,7 @@ uint32_t radio_tmr_start_us(uint8_t trx, uint32_t start_us)
/* start_us could be the current count in the timer */
uint32_t now_us = start_us;
uint32_t actual_us;
/* Setup PPI while determining the latency in doing so */
do {
@ -1459,8 +1491,24 @@ uint32_t radio_tmr_start_us(uint8_t trx, uint32_t start_us)
start_us = (now_us << 1) - start_us;
/* Setup compare event with min. 1 us offset */
actual_us = start_us + 1U;
#if defined(CONFIG_BT_CTLR_SW_SWITCH_SINGLE_TIMER)
/* When using single timer for software tIFS switching, ensure that
* the timer compare value is large enough to consider radio ISR
* latency so that the ISR is able to disable the PPI/DPPI that again
* could trigger the TXEN/RXEN task.
* The timer is cleared on Radio End and if the PPI/DPPI is not disabled
* by the Radio ISR, the compare will trigger again.
*/
uint32_t latency_ticks;
latency_ticks = HAL_TICKER_US_TO_TICKS(HAL_RADIO_ISR_LATENCY_MAX_US);
actual_us += HAL_TICKER_TICKS_TO_US(latency_ticks);
#endif /* !CONFIG_BT_CTLR_SW_SWITCH_SINGLE_TIMER */
nrf_timer_event_clear(EVENT_TIMER, NRF_TIMER_EVENT_COMPARE0);
nrf_timer_cc_set(EVENT_TIMER, 0, start_us + 1U);
nrf_timer_cc_set(EVENT_TIMER, 0, actual_us);
/* Capture the current time */
nrf_timer_task_trigger(EVENT_TIMER,
@ -1469,7 +1517,7 @@ uint32_t radio_tmr_start_us(uint8_t trx, uint32_t start_us)
now_us = EVENT_TIMER->CC[HAL_EVENT_TIMER_SAMPLE_CC_OFFSET];
} while ((now_us > start_us) && (EVENT_TIMER->EVENTS_COMPARE[0] == 0U));
return start_us + 1U;
return actual_us;
}
uint32_t radio_tmr_start_now(uint8_t trx)

15
subsys/bluetooth/controller/ll_sw/nordic/hal/nrf5/radio/radio_nrf5_resources.h
View file

@ -11,6 +11,9 @@
#define EVENT_TIMER_ID 0
#define EVENT_TIMER _CONCAT(NRF_TIMER, EVENT_TIMER_ID)
/* Single timer feature not supported when using h/w tIFS switching */
#define HAL_RADIO_ISR_LATENCY_MAX_US 0U
/* Wrapper for EVENTS_END event generated by Radio peripheral at the very end of the transmission
* or reception of a PDU on air. In case of regular PDU it is generated when last bit of CRC is
* received or transmitted.
@ -32,6 +35,12 @@
#define SW_SWITCH_TIMER EVENT_TIMER
/* Radio ISR Latency to be considered with single timer used so that the PPI/
* DPPI is disabled in time when the timer is cleared on radio end, so that
* the timer compare should not trigger TXEN/RXEN immediately on radio end.
*/
#define HAL_RADIO_ISR_LATENCY_MAX_US 150U
#if defined(CONFIG_BT_CTLR_PHY_CODED)
#define SW_SWITCH_TIMER_EVTS_COMP_BASE 3
#define SW_SWITCH_TIMER_EVTS_COMP_S2_BASE 5
@ -73,6 +82,12 @@
#define EVENT_TIMER _CONCAT(NRF_TIMER, EVENT_TIMER_ID)
#define SW_SWITCH_TIMER NRF_TIMER1
/* When using dedicated timer used for tIFS switching, compensation to avoid
* spurious TXEN/RXEN due to timer being clear is not needed.
*/
#define HAL_RADIO_ISR_LATENCY_MAX_US 0U
#define SW_SWITCH_TIMER_EVTS_COMP_BASE 0
#if defined(CONFIG_BT_CTLR_PHY_CODED)

1
subsys/bluetooth/controller/ll_sw/nordic/lll/lll_scan.c
View file

@ -939,6 +939,7 @@ static void isr_window(void *param)
uint32_t ticks_at_start;
ticks_at_start = ticker_ticks_now_get() +
HAL_TICKER_US_TO_TICKS(HAL_RADIO_ISR_LATENCY_MAX_US) +
HAL_TICKER_CNTR_CMP_OFFSET_MIN;
remainder_us = radio_tmr_start_tick(0, ticks_at_start);
#else /* !CONFIG_BT_CENTRAL && !CONFIG_BT_CTLR_ADV_EXT */