cpufreq-cpu0 uses thermal framework to register a cooling device, but doesn't
depend on it as there are dummy calls provided by thermal layer when
CONFIG_THERMAL=n. And when these calls fail, the driver is still usable.
Similar explanation is valid for regulators as well. We do have dummy calls
available for regulator APIs and the driver can work even when those calls
fail.
So, we don't really need to mention thermal and regulators as a dependency for
cpufreq-cpu0 in Kconfig as platforms without support for thermal/regulator can
also use this driver. Remove this dependency.
Signed-off-by: Viresh Kumar <viresh.kumar(a)linaro.org>
---
Rafael,
The dependency patches from regulators core are already pushed to Linus's tree
and so this patch can go in now.
drivers/cpufreq/Kconfig | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index 1fbe11f..e473d65 100644
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -185,7 +185,7 @@ config CPU_FREQ_GOV_CONSERVATIVE
config GENERIC_CPUFREQ_CPU0
tristate "Generic CPU0 cpufreq driver"
- depends on HAVE_CLK && REGULATOR && OF && THERMAL && CPU_THERMAL
+ depends on HAVE_CLK && OF
select PM_OPP
help
This adds a generic cpufreq driver for CPU0 frequency management.
--
2.0.0.rc2
Sometimes boot loaders set CPU frequency to a value outside of frequency table
present with cpufreq core. In such cases CPU might be unstable if it has to run
on that frequency for long duration of time and so its better to set it to a
frequency which is specified in frequency table.
Sachin recently found this problem with cpufreq-cpu0 driver when he was testing
it for Exynos.
Set this flag for cpufreq-cpu0 driver.
Reported-and-tested-by: Sachin Kamat <sachin.kamat(a)linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar(a)linaro.org>
---
drivers/cpufreq/cpufreq-cpu0.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c
index 09b9129..ee1ae30 100644
--- a/drivers/cpufreq/cpufreq-cpu0.c
+++ b/drivers/cpufreq/cpufreq-cpu0.c
@@ -104,7 +104,7 @@ static int cpu0_cpufreq_init(struct cpufreq_policy *policy)
}
static struct cpufreq_driver cpu0_cpufreq_driver = {
- .flags = CPUFREQ_STICKY,
+ .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
.verify = cpufreq_generic_frequency_table_verify,
.target_index = cpu0_set_target,
.get = cpufreq_generic_get,
--
2.0.0.rc2
'copy_prev_load' was recently added by commit: 18b46ab (cpufreq: governor: Be
friendly towards latency-sensitive bursty workloads).
It actually is a bit redundant as we also have 'prev_load' which can store any
integer value and can be used instead of 'copy_prev_load' by setting it zero.
True load can also turn out to be zero during long idle intervals (and hence the
actual value of 'prev_load' and the overloaded value can clash). However this is
not a problem because, if the true load was really zero in the previous
interval, it makes sense to evaluate the load afresh for the current interval
rather than copying the previous load.
So, drop 'copy_prev_load' and use 'prev_load' instead.
Update comments as well to make it more clear.
There is another change here which was probably missed by Srivatsa during the
last version of updates he made. The unlikely in the 'if' statement was covering
only half of the condition and the whole line should actually come under it.
Also checkpatch is made more silent as it was reporting this (--strict option):
CHECK: Alignment should match open parenthesis
+ if (unlikely(wall_time > (2 * sampling_rate) &&
+ j_cdbs->prev_load)) {
Signed-off-by: Viresh Kumar <viresh.kumar(a)linaro.org>
---
Resend: Updated comments/logs as suggested by Srivatsa.
drivers/cpufreq/cpufreq_governor.c | 19 ++++++++++++++-----
drivers/cpufreq/cpufreq_governor.h | 9 +++++----
2 files changed, 19 insertions(+), 9 deletions(-)
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 9004450..1b44496 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -131,15 +131,25 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
* timer would not have fired during CPU-idle periods. Hence
* an unusually large 'wall_time' (as compared to the sampling
* rate) indicates this scenario.
+ *
+ * prev_load can be zero in two cases and we must recalculate it
+ * for both cases:
+ * - during long idle intervals
+ * - explicitly set to zero
*/
- if (unlikely(wall_time > (2 * sampling_rate)) &&
- j_cdbs->copy_prev_load) {
+ if (unlikely(wall_time > (2 * sampling_rate) &&
+ j_cdbs->prev_load)) {
load = j_cdbs->prev_load;
- j_cdbs->copy_prev_load = false;
+
+ /*
+ * Perform a destructive copy, to ensure that we copy
+ * the previous load only once, upon the first wake-up
+ * from idle.
+ */
+ j_cdbs->prev_load = 0;
} else {
load = 100 * (wall_time - idle_time) / wall_time;
j_cdbs->prev_load = load;
- j_cdbs->copy_prev_load = true;
}
if (load > max_load)
@@ -373,7 +383,6 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
(j_cdbs->prev_cpu_wall - j_cdbs->prev_cpu_idle);
j_cdbs->prev_load = 100 * prev_load /
(unsigned int) j_cdbs->prev_cpu_wall;
- j_cdbs->copy_prev_load = true;
if (ignore_nice)
j_cdbs->prev_cpu_nice =
diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h
index c2a5b7e..cc401d1 100644
--- a/drivers/cpufreq/cpufreq_governor.h
+++ b/drivers/cpufreq/cpufreq_governor.h
@@ -134,12 +134,13 @@ struct cpu_dbs_common_info {
u64 prev_cpu_idle;
u64 prev_cpu_wall;
u64 prev_cpu_nice;
- unsigned int prev_load;
/*
- * Flag to ensure that we copy the previous load only once, upon the
- * first wake-up from idle.
+ * Used to keep track of load in the previous interval. However, when
+ * explicitly set to zero, it is used as a flag to ensure that we copy
+ * the previous load to the current interval only once, upon the first
+ * wake-up from idle.
*/
- bool copy_prev_load;
+ unsigned int prev_load;
struct cpufreq_policy *cur_policy;
struct delayed_work work;
/*
--
2.0.0.rc2
'copy_prev_load' was recently added by commit: 18b46ab (cpufreq: governor: Be
friendly towards latency-sensitive bursty workloads).
It actually is a bit redundant as we also have 'prev_load' which can store any
integer value and can be used instead of 'copy_prev_load' by setting it to zero
when we don't want to use previous load.
So, drop 'copy_prev_load' and use 'prev_load' instead.
Update comments as well to make it more clear.
There is another change here which was probably missed by Srivatsa during the
last version of updates he made. The unlikely in the 'if' statement was covering
only half of the condition and the whole line should actually come under it.
Also checkpatch is made more silent as it was reporting this (--strict option):
CHECK: Alignment should match open parenthesis
+ if (unlikely(wall_time > (2 * sampling_rate) &&
+ j_cdbs->prev_load)) {
Signed-off-by: Viresh Kumar <viresh.kumar(a)linaro.org>
---
drivers/cpufreq/cpufreq_governor.c | 13 ++++++++-----
drivers/cpufreq/cpufreq_governor.h | 8 ++++----
2 files changed, 12 insertions(+), 9 deletions(-)
diff --git a/drivers/cpufreq/cpufreq_governor.c b/drivers/cpufreq/cpufreq_governor.c
index 9004450..a1ad804 100644
--- a/drivers/cpufreq/cpufreq_governor.c
+++ b/drivers/cpufreq/cpufreq_governor.c
@@ -132,14 +132,18 @@ void dbs_check_cpu(struct dbs_data *dbs_data, int cpu)
* an unusually large 'wall_time' (as compared to the sampling
* rate) indicates this scenario.
*/
- if (unlikely(wall_time > (2 * sampling_rate)) &&
- j_cdbs->copy_prev_load) {
+ if (unlikely(wall_time > (2 * sampling_rate) &&
+ j_cdbs->prev_load)) {
load = j_cdbs->prev_load;
- j_cdbs->copy_prev_load = false;
+
+ /*
+ * Ensure that we copy the previous load only once, upon
+ * the first wake-up from idle.
+ */
+ j_cdbs->prev_load = 0;
} else {
load = 100 * (wall_time - idle_time) / wall_time;
j_cdbs->prev_load = load;
- j_cdbs->copy_prev_load = true;
}
if (load > max_load)
@@ -373,7 +377,6 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
(j_cdbs->prev_cpu_wall - j_cdbs->prev_cpu_idle);
j_cdbs->prev_load = 100 * prev_load /
(unsigned int) j_cdbs->prev_cpu_wall;
- j_cdbs->copy_prev_load = true;
if (ignore_nice)
j_cdbs->prev_cpu_nice =
diff --git a/drivers/cpufreq/cpufreq_governor.h b/drivers/cpufreq/cpufreq_governor.h
index c2a5b7e..d3082ee 100644
--- a/drivers/cpufreq/cpufreq_governor.h
+++ b/drivers/cpufreq/cpufreq_governor.h
@@ -134,12 +134,12 @@ struct cpu_dbs_common_info {
u64 prev_cpu_idle;
u64 prev_cpu_wall;
u64 prev_cpu_nice;
- unsigned int prev_load;
/*
- * Flag to ensure that we copy the previous load only once, upon the
- * first wake-up from idle.
+ * Used to store system load before going into idle, when set to zero:
+ * used as a flag to ensure that we copy the previous load only once,
+ * upon the first wake-up from idle.
*/
- bool copy_prev_load;
+ unsigned int prev_load;
struct cpufreq_policy *cur_policy;
struct delayed_work work;
/*
--
2.0.0.rc2