From 5225cd8079484ed27cd52040e8584616d1ef1e2c Mon Sep 17 00:00:00 2001 From: Pavel Pisa Date: Fri, 12 Jan 2007 09:57:22 +0100 Subject: [ARM] 4092/1: i.MX/MX1 CPU Frequency scaling latency definition The transition latency has to be defined and reasonably small to allow on-demand and conservative governors. The value has been defined according to manual. The imx_set_target() protected against seen out of range requests now. Signed-off-by: Pavel Pisa Acked-by: Sascha Hauer Signed-off-by: Russell King --- arch/arm/mach-imx/cpufreq.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'arch/arm/mach-imx') diff --git a/arch/arm/mach-imx/cpufreq.c b/arch/arm/mach-imx/cpufreq.c index ac5f9989566..4f66e90db74 100644 --- a/arch/arm/mach-imx/cpufreq.c +++ b/arch/arm/mach-imx/cpufreq.c @@ -184,6 +184,17 @@ static int imx_set_target(struct cpufreq_policy *policy, long sysclk; unsigned int bclk_div = 1; + /* + * Some governors do not respects CPU and policy lower limits + * which leads to bad things (division by zero etc), ensure + * that such things do not happen. + */ + if(target_freq < policy->cpuinfo.min_freq) + target_freq = policy->cpuinfo.min_freq; + + if(target_freq < policy->min) + target_freq = policy->min; + freq = target_freq * 1000; pr_debug(KERN_DEBUG "imx: requested frequency %ld Hz, mpctl0 at boot 0x%08x\n", @@ -258,7 +269,8 @@ static int __init imx_cpufreq_driver_init(struct cpufreq_policy *policy) policy->governor = CPUFREQ_DEFAULT_GOVERNOR; policy->cpuinfo.min_freq = 8000; policy->cpuinfo.max_freq = 200000; - policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL; + /* Manual states, that PLL stabilizes in two CLK32 periods */ + policy->cpuinfo.transition_latency = 4 * 1000000000LL / CLK32; return 0; } -- cgit v1.2.3