diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index d2120fcf1f3f..39cdda2c9a98 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -818,15 +818,24 @@ static void arch_timer_evtstrm_enable(int divider) static void arch_timer_configure_evtstream(void) { - int evt_stream_div, pos; + int evt_stream_div, lsb; + + /* + * As the event stream can at most be generated at half the frequency + * of the counter, use half the frequency when computing the divider. + */ + evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ / 2; + + /* + * Find the closest power of two to the divisor. If the adjacent bit + * of lsb (last set bit, starts from 0) is set, then we use (lsb + 1). + */ + lsb = fls(evt_stream_div) - 1; + if (lsb > 0 && (evt_stream_div & BIT(lsb - 1))) + lsb++; - /* Find the closest power of two to the divisor */ - evt_stream_div = arch_timer_rate / ARCH_TIMER_EVT_STREAM_FREQ; - pos = fls(evt_stream_div); - if (pos > 1 && !(evt_stream_div & (1 << (pos - 2)))) - pos--; /* enable event stream */ - arch_timer_evtstrm_enable(min(pos, 15)); + arch_timer_evtstrm_enable(max(0, min(lsb, 15))); } static void arch_counter_set_user_access(void)