From 3fddd09e59cf49dc339e2de74d31a76c1f7f172f Mon Sep 17 00:00:00 2001 From: Richard Woodruff Date: Thu, 3 Jul 2008 12:24:30 +0300 Subject: [PATCH] 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: Richard Woodruff Signed-off-by: Tony Lindgren --- arch/arm/mach-omap2/timer-gp.c | 9 +++------ arch/arm/plat-omap/dmtimer.c | 19 ++++++++++++++++++- include/asm-arm/arch-omap/dmtimer.h | 1 + 3 files changed, 22 insertions(+), 7 deletions(-) diff --git a/arch/arm/mach-omap2/timer-gp.c b/arch/arm/mach-omap2/timer-gp.c index 78d05f203f..557603f993 100644 --- a/arch/arm/mach-omap2/timer-gp.c +++ b/arch/arm/mach-omap2/timer-gp.c @@ -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); diff --git a/arch/arm/plat-omap/dmtimer.c b/arch/arm/plat-omap/dmtimer.c index 822b6bb5c7..f22506af0e 100644 --- a/arch/arm/plat-omap/dmtimer.c +++ b/arch/arm/plat-omap/dmtimer.c @@ -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) { diff --git a/include/asm-arm/arch-omap/dmtimer.h b/include/asm-arm/arch-omap/dmtimer.h index fefb276ed4..02b29e8437 100644 --- a/include/asm-arm/arch-omap/dmtimer.h +++ b/include/asm-arm/arch-omap/dmtimer.h @@ -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); -- 2.39.5