[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>
diff --git a/arch/arm/mach-imx/cpufreq.c b/arch/arm/mach-imx/cpufreq.c
index ac5f998..4f66e90 100644
--- a/arch/arm/mach-imx/cpufreq.c
+++ b/arch/arm/mach-imx/cpufreq.c
@@ -184,6 +184,17 @@
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 @@
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;
}