Commit 3fddd09e authored by Richard Woodruff's avatar Richard Woodruff Committed by Tony Lindgren
Browse files

ARM: OMAP: DMTimer: Optimize by adding load and start 



This patch optimizes the timer load and start sequence.  By combining the
load and start a needless posted wait can be removed from the system timer
execution path.

* Before patch register writes are taking up .078% @ 500MHz during idle.

 Address                 |total  |min  |max      |avr     |count|ratio%
 old\process\default_idle|7.369s |0.0us|999.902ms|14.477ms|509. |62.661%
 ld\Global\cpu_v7_do_idle|4.265s |0.0us|375.786ms|24.374ms|175. |36.270%
                (UNKNOWN)|17.503ms|0.us|531.080us|5.119us|3419. |0.148%
 r\omap_dm_timer_set_load|8.135ms|0.0us|79.887us|15.065us|540.  |0.069% <--
 \vmlinux-old\Global\_end|2.023ms|0.0us|4.000us|0.560us|3613.   |0.017%
 -old\Global\__raw_readsw|1.962ms|0.0us|108.610us|9.167us|214.  |0.016%
 old\smc91x\smc_interrupt|1.353ms|0.0us|10.212us|2.348us|576.   |0.011%
 s/namei\__link_path_walk|1.161ms|0.0us|4.310us|0.762us|  1524. |0.009%
 \omap_dm_timer_write_reg|1.085ms|0.0us|126.150us|2.153us|504.  |0.009% <--

* After patch timer functions do not show up in top listings for long captures.

Signed-off-by: default avatarRichard Woodruff <r-woodruff2@ti.com>
Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
parent 0f0d0807

arch/arm/mach-omap2/timer-gp.c

+3 −6
Original line number Diff line number Diff line
@@ -59,8 +59,7 @@ static struct irqaction omap2_gp_timer_irq = { 
static int omap2_gp_timer_set_next_event(unsigned long cycles,

					 struct clock_event_device *evt)

{

	omap_dm_timer_set_load(gptimer, 0, 0xffffffff - cycles);

	omap_dm_timer_start(gptimer);

	omap_dm_timer_set_load_start(gptimer, 0, 0xffffffff - cycles);



	return 0;

}
@@ -77,8 +76,7 @@ static void omap2_gp_timer_set_mode(enum clock_event_mode mode, 
		period = clk_get_rate(omap_dm_timer_get_fclk(gptimer)) / HZ;

		period -= 1;



		omap_dm_timer_set_load(gptimer, 1, 0xffffffff - period);

		omap_dm_timer_start(gptimer);

		omap_dm_timer_set_load_start(gptimer, 1, 0xffffffff - period);

		break;

	case CLOCK_EVT_MODE_ONESHOT:

		break;
@@ -172,8 +170,7 @@ static void __init omap2_gp_clocksource_init(void) 
	tick_rate = clk_get_rate(omap_dm_timer_get_fclk(gpt));

	tick_period = (tick_rate / HZ) - 1;



	omap_dm_timer_set_load(gpt, 1, 0);

	omap_dm_timer_start(gpt);

	omap_dm_timer_set_load_start(gpt, 1, 0);



	clocksource_gpt.mult =

		clocksource_khz2mult(tick_rate/1000, clocksource_gpt.shift);

arch/arm/plat-omap/dmtimer.c

+18 −1
Original line number Diff line number Diff line
@@ -546,6 +546,24 @@ void omap_dm_timer_set_load(struct omap_dm_timer *timer, int autoreload, 
	omap_dm_timer_write_reg(timer, OMAP_TIMER_TRIGGER_REG, 0);

}



/* Optimized set_load which removes costly spin wait in timer_start */

void omap_dm_timer_set_load_start(struct omap_dm_timer *timer, int autoreload,

                            unsigned int load)

{

	u32 l;



	l = omap_dm_timer_read_reg(timer, OMAP_TIMER_CTRL_REG);

	if (autoreload)

		l |= OMAP_TIMER_CTRL_AR;

	else

		l &= ~OMAP_TIMER_CTRL_AR;

	l |= OMAP_TIMER_CTRL_ST;



	omap_dm_timer_write_reg(timer, OMAP_TIMER_COUNTER_REG, load);

	omap_dm_timer_write_reg(timer, OMAP_TIMER_LOAD_REG, load);

	omap_dm_timer_write_reg(timer, OMAP_TIMER_CTRL_REG, l);

}



void omap_dm_timer_set_match(struct omap_dm_timer *timer, int enable,

			     unsigned int match)

{
@@ -560,7 +578,6 @@ void omap_dm_timer_set_match(struct omap_dm_timer *timer, int enable, 
	omap_dm_timer_write_reg(timer, OMAP_TIMER_MATCH_REG, match);

}





void omap_dm_timer_set_pwm(struct omap_dm_timer *timer, int def_on,

			   int toggle, int trigger)

{

include/asm-arm/arch-omap/dmtimer.h

+1 −0
Original line number Diff line number Diff line
@@ -66,6 +66,7 @@ void omap_dm_timer_stop(struct omap_dm_timer *timer); 


void omap_dm_timer_set_source(struct omap_dm_timer *timer, int source);

void omap_dm_timer_set_load(struct omap_dm_timer *timer, int autoreload, unsigned int value);

void omap_dm_timer_set_load_start(struct omap_dm_timer *timer, int autoreload, unsigned int value);

void omap_dm_timer_set_match(struct omap_dm_timer *timer, int enable, unsigned int match);

void omap_dm_timer_set_pwm(struct omap_dm_timer *timer, int def_on, int toggle, int trigger);

void omap_dm_timer_set_prescaler(struct omap_dm_timer *timer, int prescaler);

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