OPP: Use a single mechanism to free the OPP table

Currently there are two separate ways to free the OPP table based on how
it is created in the first place.

We call _dev_pm_opp_remove_table() to free the static and/or dynamic
OPP, OPP list devices, etc. This is done for the case where the OPP
table is added while initializing the OPPs, like via the path
dev_pm_opp_of_add_table().

We also call dev_pm_opp_put_opp_table() in some cases which eventually
frees the OPP table structure once the reference count reaches 0. This
is used by the first case as well as other cases like
dev_pm_opp_set_regulators() where the OPPs aren't necessarily
initialized at this point.

This whole thing is a bit unclear and messy and obstruct any further
cleanup/fixup of OPP core.

This patch tries to streamline this by keeping a single path for OPP
table destruction, i.e. dev_pm_opp_put_opp_table().

All the cleanup happens in _opp_table_kref_release() now after the
reference count reaches 0. _dev_pm_opp_remove_table() is removed as it
isn't required anymore.

We don't drop the reference to the OPP table after creating it from
_of_add_opp_table_v{1|2}() anymore and the same is dropped only when we
try to remove them.

Tested-by: Niklas Cassel <niklas.cassel@linaro.org>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

1 files changed, 16 insertions, 38 deletions

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index 2319ad4a0177..d3e33fd32694 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -867,23 +867,24 @@ struct opp_table *dev_pm_opp_get_opp_table_indexed(struct device *dev,
 static void _opp_table_kref_release(struct kref *kref)
 {
 	struct opp_table *opp_table = container_of(kref, struct opp_table, kref);
-	struct opp_device *opp_dev;
+	struct opp_device *opp_dev, *temp;
 
 	/* Release clk */
 	if (!IS_ERR(opp_table->clk))
 		clk_put(opp_table->clk);
 
-	/*
-	 * No need to take opp_table->lock here as we are guaranteed that no
-	 * references to the OPP table are taken at this point.
-	 */
-	opp_dev = list_first_entry(&opp_table->dev_list, struct opp_device,
-				   node);
+	WARN_ON(!list_empty(&opp_table->opp_list));
 
-	_remove_opp_dev(opp_dev, opp_table);
+	list_for_each_entry_safe(opp_dev, temp, &opp_table->dev_list, node) {
+		/*
+		 * The OPP table is getting removed, drop the performance state
+		 * constraints.
+		 */
+		if (opp_table->genpd_performance_state)
+			dev_pm_genpd_set_performance_state((struct device *)(opp_dev->dev), 0);
 
-	/* dev_list must be empty now */
-	WARN_ON(!list_empty(&opp_table->dev_list));
+		_remove_opp_dev(opp_dev, opp_table);
+	}
 
 	mutex_destroy(&opp_table->lock);
 	list_del(&opp_table->node);
@@ -1758,33 +1759,6 @@ int dev_pm_opp_unregister_notifier(struct device *dev,
 }
 EXPORT_SYMBOL(dev_pm_opp_unregister_notifier);
 
-/*
- * Free OPPs either created using static entries present in DT.
- */
-void _dev_pm_opp_remove_table(struct opp_table *opp_table, struct device *dev)
-{
-	/* Protect dev_list */
-	mutex_lock(&opp_table->lock);
-
-	/* Find if opp_table manages a single device */
-	if (list_is_singular(&opp_table->dev_list)) {
-		/* Free static OPPs */
-		_put_opp_list_kref(opp_table);
-
-		/*
-		 * The OPP table is getting removed, drop the performance state
-		 * constraints.
-		 */
-		if (opp_table->genpd_performance_state)
-			dev_pm_genpd_set_performance_state(dev, 0);
-	} else {
-		_put_opp_list_kref(opp_table);
-		_remove_opp_dev(_find_opp_dev(dev, opp_table), opp_table);
-	}
-
-	mutex_unlock(&opp_table->lock);
-}
-
 void _dev_pm_opp_find_and_remove_table(struct device *dev)
 {
 	struct opp_table *opp_table;
@@ -1802,8 +1776,12 @@ void _dev_pm_opp_find_and_remove_table(struct device *dev)
 		return;
 	}
 
-	_dev_pm_opp_remove_table(opp_table, dev);
+	_put_opp_list_kref(opp_table);
+
+	/* Drop reference taken by _find_opp_table() */
+	dev_pm_opp_put_opp_table(opp_table);
 
+	/* Drop reference taken while the OPP table was added */
 	dev_pm_opp_put_opp_table(opp_table);
 }