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clocksource: samsung_pwm_timer: Correct programming of clock events

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In current code, the tick count value programmed to the hardware is
always decremented by one. This is reasonable for periodic mode, since
there is one extra tick between 0 and COUNT (after reloading), but it
makes oneshot events happen 1 tick earlier than requested, because the
interrupt is triggered on transition from 1 to 0.

This patch removes the decrementation from PWM channel setup code and
moves it instead to periodic timer setup, to make both periodic and
oneshot modes work correctly.

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>
This commit is contained in:
Tomasz Figa 2013-04-23 17:46:29 +02:00 committed by Olof Johansson
parent e9b852b8a7
commit 6fe4dfd041
1 changed files with 2 additions and 4 deletions
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6
drivers/clocksource/samsung_pwm_timer.c
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@ -138,8 +138,6 @@ static void samsung_time_setup(unsigned int channel, unsigned long tcnt)
tcon = __raw_readl(pwm.base + REG_TCON);
tcnt--;
tcon &= ~(TCON_START(tcon_chan) | TCON_AUTORELOAD(tcon_chan));
tcon |= TCON_MANUALUPDATE(tcon_chan);
@ -187,7 +185,7 @@ static int samsung_set_next_event(unsigned long cycles,
static void samsung_timer_resume(void)
{
/* event timer restart */
samsung_time_setup(pwm.event_id, pwm.clock_count_per_tick);
samsung_time_setup(pwm.event_id, pwm.clock_count_per_tick - 1);
samsung_time_start(pwm.event_id, true);
/* source timer restart */
@ -202,7 +200,7 @@ static void samsung_set_mode(enum clock_event_mode mode,
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
samsung_time_setup(pwm.event_id, pwm.clock_count_per_tick);
samsung_time_setup(pwm.event_id, pwm.clock_count_per_tick - 1);
samsung_time_start(pwm.event_id, true);
break;