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authorPavel Pisa <ppisa@pikron.com>2007-01-12 09:57:22 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2007-01-24 11:59:56 +0000
commit5225cd8079484ed27cd52040e8584616d1ef1e2c (patch)
treeb0e13402a8845e996ec4b4b7e043786cbe78d3cf /arch/arm
parent3ea163e44c041b9e1d7314998dfbfd4fbc6eea20 (diff)
[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 <pisa@cmp.felk.cvut.cz> Acked-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/mach-imx/cpufreq.c14
1 files changed, 13 insertions, 1 deletions
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;
}