[CPUFREQ] Fix ondemand to not request targets outside policy limits
Nagananda.Chumbalkar@hp.com [Mon, 21 Dec 2009 22:40:52 +0000 (23:40 +0100)]
Dominik said:
target_freq cannot be below policy->min or above policy->max.
If it were, the whole cpufreq subsystem is broken.

But (answer):
I think the "ondemand" governor can ask for a target frequency that is
below policy->min.
...
A patch such as below may be needed to sanitize the target frequency
requested by "ondemand". The "conservative" governor already has this check:

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dave Jones <davej@redhat.com>

# diff -bur x/drivers/cpufreq/cpufreq_ondemand.c.orig y/drivers/cpufreq/cpufreq_ondemand.c

drivers/cpufreq/cpufreq_ondemand.c

index 4b34ade..bd444dc 100644 (file)
@@ -554,6 +554,9 @@ static void dbs_check_cpu(struct cpu_dbs_info_s *this_dbs_info)
                                (dbs_tuners_ins.up_threshold -
                                 dbs_tuners_ins.down_differential);
 
+               if (freq_next < policy->min)
+                       freq_next = policy->min;
+
                if (!dbs_tuners_ins.powersave_bias) {
                        __cpufreq_driver_target(policy, freq_next,
                                        CPUFREQ_RELATION_L);