clocksource: samsung_pwm_timer: Correct programming of clock events (6fe4dfd0) · Commits · e / devices / android_kernel_xiaomi_markw

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>

drivers/clocksource/samsung_pwm_timer.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -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;