PM / OPP: optimize dev_pm_opp_set_rate() performance a bit

In dev_pm_opp_set_rate(), _find_opp_table() is called 4 times: once by
_get_opp_clk(), once by dev_pm_opp_set_rate() itself, and twice by
dev_pm_opp_find_freq_ceil(). If there are several opp_tables in the
system, three times of opp table finding is a big waste. This patch
reduced the call of _find_opp_table() to twice.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 19 insertions, 12 deletions

diff --git a/drivers/base/power/opp/core.c b/drivers/base/power/opp/core.c
index 7c04c87738a6..df0c70963d9e 100644
--- a/drivers/base/power/opp/core.c
+++ b/drivers/base/power/opp/core.c
@@ -402,6 +402,22 @@ struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_exact);
 
+static noinline struct dev_pm_opp *_find_freq_ceil(struct opp_table *opp_table,
+                                                   unsigned long *freq)
+{
+        struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE);
+
+        list_for_each_entry_rcu(temp_opp, &opp_table->opp_list, node) {
+                if (temp_opp->available && temp_opp->rate >= *freq) {
+                        opp = temp_opp;
+                        *freq = opp->rate;
+                        break;
+                }
+        }
+
+        return opp;
+}
+
 /**
  * dev_pm_opp_find_freq_ceil() - Search for an rounded ceil freq
  * @dev:        device for which we do this operation
@@ -427,7 +443,6 @@ struct dev_pm_opp *dev_pm_opp_find_freq_ceil(struct device *dev,
                                              unsigned long *freq)
 {
         struct opp_table *opp_table;
-        struct dev_pm_opp *temp_opp, *opp = ERR_PTR(-ERANGE);
 
         opp_rcu_lockdep_assert();
 
@@ -440,15 +455,7 @@ struct dev_pm_opp *dev_pm_opp_find_freq_ceil(struct device *dev,
         if (IS_ERR(opp_table))
                 return ERR_CAST(opp_table);
 
-        list_for_each_entry_rcu(temp_opp, &opp_table->opp_list, node) {
-                if (temp_opp->available && temp_opp->rate >= *freq) {
-                        opp = temp_opp;
-                        *freq = opp->rate;
-                        break;
-                }
-        }
-
-        return opp;
+        return _find_freq_ceil(opp_table, freq);
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_find_freq_ceil);
 
@@ -612,7 +619,7 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
                 return PTR_ERR(opp_table);
         }
 
-        old_opp = dev_pm_opp_find_freq_ceil(dev, &old_freq);
+        old_opp = _find_freq_ceil(opp_table, &old_freq);
         if (!IS_ERR(old_opp)) {
                 ou_volt = old_opp->u_volt;
                 ou_volt_min = old_opp->u_volt_min;
@@ -622,7 +629,7 @@ int dev_pm_opp_set_rate(struct device *dev, unsigned long target_freq)
                         __func__, old_freq, PTR_ERR(old_opp));
         }
 
-        opp = dev_pm_opp_find_freq_ceil(dev, &freq);
+        opp = _find_freq_ceil(opp_table, &freq);
         if (IS_ERR(opp)) {
                 ret = PTR_ERR(opp);
                 dev_err(dev, "%s: failed to find OPP for freq %lu (%d)\n",