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>
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);