diff options
| author | Tomasz Figa | 2013-04-23 17:46:30 +0200 |
|---|---|---|
| committer | Olof Johansson | 2013-04-28 12:17:05 -0700 |
| commit | 81d4f7bfdc9417e7d8fc1133c762daa4458eec5e (patch) | |
| tree | a9942c9fb2ec8d830ead2fb01517b7f95985fb80 | |
| parent | 6fe4dfd041dadbc1cc2460ed8680f2734dc3dc95 (diff) | |
clocksource: samsung_pwm_timer: Work around rounding errors in clockevents core
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 <t.figa@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Olof Johansson <olof@lixom.net>
| -rw-r--r-- | drivers/clocksource/samsung_pwm_timer.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/drivers/clocksource/samsung_pwm_timer.c b/drivers/clocksource/samsung_pwm_timer.c index 92b2f130ae9b..0234c8d2c8f2 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); |