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Subject[PATCH 09/11] OPP: Use a single mechanism to free the OPP table
Date
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.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
drivers/opp/core.c | 54 ++++++++++++++--------------------------------
drivers/opp/of.c | 32 +++++++++++++++------------
drivers/opp/opp.h | 2 +-
3 files changed, 35 insertions(+), 53 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);
}

diff --git a/drivers/opp/of.c b/drivers/opp/of.c
index 9c98682af374..a5cba0234220 100644
--- a/drivers/opp/of.c
+++ b/drivers/opp/of.c
@@ -407,14 +407,17 @@ static int _of_add_opp_table_v2(struct device *dev, struct device_node *opp_np,
opp_table = _managed_opp(opp_np);
if (opp_table) {
/* OPPs are already managed */
- if (!_add_opp_dev(dev, opp_table))
+ if (!_add_opp_dev(dev, opp_table)) {
ret = -ENOMEM;
- else if (!opp_table->parsed_static_opps)
- goto initialize_static_opps;
- else
+ goto put_opp_table;
+ }
+
+ if (opp_table->parsed_static_opps) {
kref_get(&opp_table->list_kref);
+ return 0;
+ }

- goto put_opp_table;
+ goto initialize_static_opps;
}

opp_table = dev_pm_opp_get_opp_table_indexed(dev, index);
@@ -432,17 +435,15 @@ static int _of_add_opp_table_v2(struct device *dev, struct device_node *opp_np,
if (ret) {
dev_err(dev, "%s: Failed to add OPP, %d\n", __func__,
ret);
- _dev_pm_opp_remove_table(opp_table, dev);
of_node_put(np);
- goto put_opp_table;
+ goto put_list_kref;
}
}

/* There should be one of more OPP defined */
if (WARN_ON(!count)) {
ret = -ENOENT;
- _put_opp_list_kref(opp_table);
- goto put_opp_table;
+ goto put_list_kref;
}

list_for_each_entry(opp, &opp_table->opp_list, node)
@@ -453,8 +454,7 @@ static int _of_add_opp_table_v2(struct device *dev, struct device_node *opp_np,
dev_err(dev, "Not all nodes have performance state set (%d: %d)\n",
count, pstate_count);
ret = -ENOENT;
- _dev_pm_opp_remove_table(opp_table, dev);
- goto put_opp_table;
+ goto put_list_kref;
}

if (pstate_count)
@@ -462,6 +462,10 @@ static int _of_add_opp_table_v2(struct device *dev, struct device_node *opp_np,

opp_table->parsed_static_opps = true;

+ return 0;
+
+put_list_kref:
+ _put_opp_list_kref(opp_table);
put_opp_table:
dev_pm_opp_put_opp_table(opp_table);

@@ -507,13 +511,13 @@ static int _of_add_opp_table_v1(struct device *dev)
if (ret) {
dev_err(dev, "%s: Failed to add OPP %ld (%d)\n",
__func__, freq, ret);
- _dev_pm_opp_remove_table(opp_table, dev);
- break;
+ _put_opp_list_kref(opp_table);
+ dev_pm_opp_put_opp_table(opp_table);
+ return ret;
}
nr -= 2;
}

- dev_pm_opp_put_opp_table(opp_table);
return ret;
}

diff --git a/drivers/opp/opp.h b/drivers/opp/opp.h
index 3b1d94748a4d..b260fb7b307a 100644
--- a/drivers/opp/opp.h
+++ b/drivers/opp/opp.h
@@ -190,11 +190,11 @@ struct opp_table {

/* Routines internal to opp core */
void dev_pm_opp_get(struct dev_pm_opp *opp);
+void _opp_remove_all_static(struct opp_table *opp_table);
void _get_opp_table_kref(struct opp_table *opp_table);
int _get_opp_count(struct opp_table *opp_table);
struct opp_table *_find_opp_table(struct device *dev);
struct opp_device *_add_opp_dev(const struct device *dev, struct opp_table *opp_table);
-void _dev_pm_opp_remove_table(struct opp_table *opp_table, struct device *dev);
void _dev_pm_opp_find_and_remove_table(struct device *dev);
struct dev_pm_opp *_opp_allocate(struct opp_table *opp_table);
void _opp_free(struct dev_pm_opp *opp);
--
2.18.0.rc1.242.g61856ae69a2c
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