PM: domains: Measure suspend/resume latencies in genpd based on governor

The QoS latency measurements for devices in genpd_runtime_suspend|resume()
are superfluous, unless the corresponding genpd has a governor assigned to
it, which would make use of the data.

Therefore, let's improve the behaviour in genpd by making the measurements
conditional, based upon if there's a governor assigned.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 4c059a8..2cdfbe4 100644 (file)
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -881,7 +881,7 @@ static int genpd_runtime_suspend(struct device *dev)
        struct generic_pm_domain_data *gpd_data = dev_gpd_data(dev);
        struct gpd_timing_data *td = gpd_data->td;
        bool runtime_pm = pm_runtime_enabled(dev);
-       ktime_t time_start;
+       ktime_t time_start = 0;
        s64 elapsed_ns;
        int ret;
 
@@ -902,8 +902,7 @@ static int genpd_runtime_suspend(struct device *dev)
                return -EBUSY;
 
        /* Measure suspend latency. */
-       time_start = 0;
-       if (runtime_pm)
+       if (td && runtime_pm)
                time_start = ktime_get();
 
        ret = __genpd_runtime_suspend(dev);
@@ -917,9 +916,9 @@ static int genpd_runtime_suspend(struct device *dev)
        }
 
        /* Update suspend latency value if the measured time exceeds it. */
-       if (runtime_pm) {
+       if (td && runtime_pm) {
                elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));
-               if (td && (elapsed_ns > td->suspend_latency_ns)) {
+               if (elapsed_ns > td->suspend_latency_ns) {
                        td->suspend_latency_ns = elapsed_ns;
                        dev_dbg(dev, "suspend latency exceeded, %lld ns\n",
                                elapsed_ns);
@@ -956,11 +955,10 @@ static int genpd_runtime_resume(struct device *dev)
        struct generic_pm_domain *genpd;
        struct generic_pm_domain_data *gpd_data = dev_gpd_data(dev);
        struct gpd_timing_data *td = gpd_data->td;
-       bool runtime_pm = pm_runtime_enabled(dev);
-       ktime_t time_start;
+       bool timed = td && pm_runtime_enabled(dev);
+       ktime_t time_start = 0;
        s64 elapsed_ns;
        int ret;
-       bool timed = true;
 
        dev_dbg(dev, "%s()\n", __func__);
 
@@ -988,8 +986,7 @@ static int genpd_runtime_resume(struct device *dev)
 
  out:
        /* Measure resume latency. */
-       time_start = 0;
-       if (timed && runtime_pm)
+       if (timed)
                time_start = ktime_get();
 
        ret = genpd_start_dev(genpd, dev);
@@ -1001,9 +998,9 @@ static int genpd_runtime_resume(struct device *dev)
                goto err_stop;
 
        /* Update resume latency value if the measured time exceeds it. */
-       if (timed && runtime_pm) {
+       if (timed) {
                elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));
-               if (td && (elapsed_ns > td->resume_latency_ns)) {
+               if (elapsed_ns > td->resume_latency_ns) {
                        td->resume_latency_ns = elapsed_ns;
                        dev_dbg(dev, "resume latency exceeded, %lld ns\n",
                                elapsed_ns);