There is no limitation in the ondemand or conservative governors which
disallow the transition_latency to be greater than 10 ms.
The max_transition_latency field is rather used to disallow automatic
dynamic frequency switching for platforms which didn't wanted these
governors to run.
Replace max_transition_latency with a boolean (dynamic_switching) and
check for transition_latency == CPUFREQ_ETERNAL along with that. This
makes it pretty straight forward to read/understand now.
Signed-off-by: Viresh Kumar <viresh.ku...@linaro.org>
---
drivers/cpufreq/cpufreq.c | 8 ++++----
drivers/cpufreq/cpufreq_governor.h | 2 +-
include/linux/cpufreq.h | 9 ++-------
3 files changed, 7 insertions(+), 12 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 9bf97a366029..dcef293c5e2c 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -1988,13 +1988,13 @@ static int cpufreq_init_governor(struct cpufreq_policy
*policy)
if (!policy->governor)
return -EINVAL;
- if (policy->governor->max_transition_latency &&
- policy->cpuinfo.transition_latency >
- policy->governor->max_transition_latency) {
+ /* Platform doesn't want dynamic frequency switching ? */
+ if (policy->governor->dynamic_switching &&
+ policy->cpuinfo.transition_latency == CPUFREQ_ETERNAL) {
struct cpufreq_governor *gov = cpufreq_fallback_governor();
if (gov) {
- pr_warn("%s governor failed, too long transition
latency of HW, fallback to %s governor\n",
+ pr_warn("Transition latency set to CPUFREQ_ETERNAL,
can't use %s governor. Fallback to %s governor\n",
policy->governor->name, gov->name);
policy->governor = gov;
} else {
diff --git a/drivers/cpufreq/cpufreq_governor.h
b/drivers/cpufreq/cpufreq_governor.h
index 0236ec2cd654..7b7839c45fba 100644
--- a/drivers/cpufreq/cpufreq_governor.h
+++ b/drivers/cpufreq/cpufreq_governor.h
@@ -160,7 +160,7 @@ void cpufreq_dbs_governor_limits(struct cpufreq_policy
*policy);
#define CPUFREQ_DBS_GOVERNOR_INITIALIZER(_name_) \
{ \
.name = _name_, \
- .max_transition_latency = TRANSITION_LATENCY_LIMIT, \
+ .dynamic_switching = true, \
.owner = THIS_MODULE, \
.init = cpufreq_dbs_governor_init, \
.exit = cpufreq_dbs_governor_exit, \
diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index 905117bd5012..3d8c52b3b5df 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -487,14 +487,10 @@ static inline unsigned long cpufreq_scale(unsigned long
old, u_int div,
* polling frequency is 1000 times the transition latency of the processor. The
* ondemand governor will work on any processor with transition latency <=
10ms,
* using appropriate sampling rate.
- *
- * For CPUs with transition latency > 10ms (mostly drivers with
CPUFREQ_ETERNAL)
- * the ondemand governor will not work. All times here are in us
(microseconds).
*/
#define MIN_SAMPLING_RATE_RATIO (2)
#define LATENCY_MULTIPLIER (1000)
#define MIN_LATENCY_MULTIPLIER (20)
-#define TRANSITION_LATENCY_LIMIT (10 * 1000 * 1000)
struct cpufreq_governor {
char name[CPUFREQ_NAME_LEN];
@@ -507,9 +503,8 @@ struct cpufreq_governor {
char *buf);
int (*store_setspeed) (struct cpufreq_policy *policy,
unsigned int freq);
- unsigned int max_transition_latency; /* HW must be able to switch to
- next freq faster than this value in nano secs or we
- will fallback to performance governor */
+ /* For governors which change frequency dynamically by themselves */
+ bool dynamic_switching;
struct list_head governor_list;
struct module *owner;
};
--
2.13.0.71.gd7076ec9c9cb
