From 3c802a95eda109adf16b28386c636697e6836fae Mon Sep 17 00:00:00 2001 From: Marcin Bukat Date: Fri, 12 Apr 2013 09:27:16 +0200 Subject: rk27xx: make udelay() more accurate Change-Id: Ic448c4e5ec52af6aaeebccee4feea49954394677 --- firmware/target/arm/rk27xx/system-rk27xx.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) (limited to 'firmware/target') diff --git a/firmware/target/arm/rk27xx/system-rk27xx.c b/firmware/target/arm/rk27xx/system-rk27xx.c index 9f089e8170..a36b4e9581 100644 --- a/firmware/target/arm/rk27xx/system-rk27xx.c +++ b/firmware/target/arm/rk27xx/system-rk27xx.c @@ -177,19 +177,13 @@ int system_memory_guard(int newmode) /* usecs may be at most 2^32/200 (~21 seconds) for 200MHz max cpu freq */ void udelay(unsigned usecs) { - unsigned cycles_per_usec; unsigned delay; - if (cpu_frequency == CPUFREQ_MAX) { - cycles_per_usec = (CPUFREQ_MAX + 999999) / 1000000; - } else { - cycles_per_usec = (CPUFREQ_NORMAL + 999999) / 1000000; - } - - delay = (usecs * cycles_per_usec + 3) / 4; + delay = (usecs * (cpu_frequency/1000000)) / 5; asm volatile( "1: subs %0, %0, #1 \n" /* 1 cycle */ + " nop \n" /* 1 cycle */ " bne 1b \n" /* 3 cycles */ : : "r"(delay) ); -- cgit v1.2.3