Due to rounding errors in clockevents core (in conversions between ticks and nsecs), it might happen that the set_next_event callback gets called with cycles = 0, causing the code to incorrectly program the PWM timer.
This patch modifies the callback to program the timer for 1 tick, if received tick count value is 0. Signed-off-by: Tomasz Figa <[email protected]> Signed-off-by: Kyungmin Park <[email protected]> --- drivers/clocksource/samsung_pwm_timer.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/clocksource/samsung_pwm_timer.c b/drivers/clocksource/samsung_pwm_timer.c index 92b2f13..0234c8d 100644 --- a/drivers/clocksource/samsung_pwm_timer.c +++ b/drivers/clocksource/samsung_pwm_timer.c @@ -176,6 +176,19 @@ static void samsung_time_start(unsigned int channel, bool periodic) static int samsung_set_next_event(unsigned long cycles, struct clock_event_device *evt) { + /* + * This check is needed to account for internal rounding + * errors inside clockevents core, which might result in + * passing cycles = 0, which in turn would not generate any + * timer interrupt and hang the system. + * + * Another solution would be to set up the clockevent device + * with min_delta = 2, but this would unnecessarily increase + * the minimum sleep period. + */ + if (!cycles) + cycles = 1; + samsung_time_setup(pwm.event_id, cycles); samsung_time_start(pwm.event_id, false); -- 1.8.2.1 _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
