cpufreq: Add CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING cpufreq driver flag
The policy->transition_latency field is used for multiple purposes
today and its not straight forward at all. This is how it is used:
A. Set the correct transition_latency value.
B. Set it to CPUFREQ_ETERNAL because:
1. We don't want automatic dynamic switching (with
ondemand/conservative) to happen at all.
2. We don't know the transition latency.
This patch handles the B.1. case in a more readable way. A new flag for
the cpufreq drivers is added to disallow use of cpufreq governors which
have dynamic_switching flag set.
All the current cpufreq drivers which are setting transition_latency
unconditionally to CPUFREQ_ETERNAL are updated to use it. They don't
need to set transition_latency anymore.
There shouldn't be any functional change after this patch.
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 88139e5..6ec589c 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2005,11 +2005,12 @@ static int cpufreq_init_governor(struct cpufreq_policy *policy)
/* Platform doesn't want dynamic frequency switching ? */
if (policy->governor->dynamic_switching &&
- policy->cpuinfo.transition_latency == CPUFREQ_ETERNAL) {
+ (cpufreq_driver->flags & CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING ||
+ policy->cpuinfo.transition_latency == CPUFREQ_ETERNAL)) {
struct cpufreq_governor *gov = cpufreq_fallback_governor();
if (gov) {
- pr_warn("Transition latency set to CPUFREQ_ETERNAL, can't use %s governor. Fallback to %s governor\n",
+ pr_warn("Can't use %s governor as dynamic switching is disallowed. Fallback to %s governor\n",
policy->governor->name, gov->name);
policy->governor = gov;
} else {