[PATCH 4/4] PM / Domains: Propagate performance state updates

Viresh Kumar
2018-11-05T06:37:27Z

This commit updates genpd core to start propagating performance state
updates to master domains that have their set_performance_state()
callback set.

A genpd handles two type of performance states now. The first one is the
performance state requirement put on the genpd by the devices and
sub-domains under it, which is already represented by
genpd->performance_state. The second type, introduced in this commit, is
the performance state requirement(s) put by the genpd on its master
domain(s). There is a separate value required for each master that the
genpd has and so a new field is added to the struct gpd_link
(link->performance_state), which represents the link between a genpd and
its master. The struct gpd_link also got another field
prev_performance_state, which is used by genpd core as a temporary
variable during transitions.

We need to propagate setting performance state while powering-on a genpd
as well, as we ignore performance state requirements from sub-domains
which are powered-off. For this reason _genpd_power_on() also received
the additional parameter, depth, which is used for hierarchical locking
within genpd.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
---
drivers/base/power/domain.c | 107 +++++++++++++++++++++++++++++-------
include/linux/pm_domain.h | 4 ++
2 files changed, 92 insertions(+), 19 deletions(-)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 6d2e9b3406f1..81e02c5f753f 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -239,28 +239,86 @@ static void genpd_update_accounting(struct generic_pm_domain *genpd)
static inline void genpd_update_accounting(struct generic_pm_domain *genpd) {}
#endif

+static int _genpd_reeval_performance_state(struct generic_pm_domain *genpd,
+ unsigned int state, int depth);
+
static int _genpd_set_performance_state(struct generic_pm_domain *genpd,
- unsigned int state)
+ unsigned int state, int depth)
{
+ struct generic_pm_domain *master;
+ struct gpd_link *link;
+ unsigned int mstate;
int ret;

if (!genpd_status_on(genpd))
goto out;

+ /* Propagate to masters of genpd */
+ list_for_each_entry(link, &genpd->slave_links, slave_node) {
+ master = link->master;
+
+ if (!master->set_performance_state)
+ continue;
+
+ /* Find master's performance state */
+ mstate = dev_pm_opp_xlate_performance_state(genpd->opp_table,
+ master->opp_table, state);
+ if (unlikely(!mstate))
+ goto err;
+
+ genpd_lock_nested(master, depth + 1);
+
+ link->prev_performance_state = link->performance_state;
+ link->performance_state = mstate;
+ ret = _genpd_reeval_performance_state(master, mstate, depth + 1);
+ if (ret)
+ link->performance_state = link->prev_performance_state;
+
+ genpd_unlock(master);
+
+ if (ret)
+ goto err;
+ }
+
ret = genpd->set_performance_state(genpd, state);
if (ret)
- return ret;
+ goto err;

out:
genpd->performance_state = state;
return 0;
+
+err:
+ /* Encountered an error, lets rollback */
+ list_for_each_entry_continue_reverse(link, &genpd->slave_links,
+ slave_node) {
+ master = link->master;
+
+ if (!master->set_performance_state)
+ continue;
+
+ genpd_lock_nested(master, depth + 1);
+
+ mstate = link->prev_performance_state;
+ link->performance_state = mstate;
+
+ if (_genpd_reeval_performance_state(master, mstate, depth + 1)) {
+ pr_err("%s: Failed to roll back to %d performance state\n",
+ master->name, mstate);
+ }
+
+ genpd_unlock(master);
+ }
+
+ return ret;
}

static int _genpd_reeval_performance_state(struct generic_pm_domain *genpd,
- unsigned int state)
+ unsigned int state, int depth)
{
struct generic_pm_domain_data *pd_data;
struct pm_domain_data *pdd;
+ struct gpd_link *link;

/* New requested state is same as Max requested state */
if (state == genpd->performance_state)
@@ -278,21 +336,30 @@ static int _genpd_reeval_performance_state(struct generic_pm_domain *genpd,
state = pd_data->performance_state;
}

- if (state == genpd->performance_state)
- return 0;
-
/*
- * We aren't propagating performance state changes of a subdomain to its
- * masters as we don't have hardware that needs it. Over that, the
- * performance states of subdomain and its masters may not have
- * one-to-one mapping and would require additional information. We can
- * get back to this once we have hardware that needs it. For that
- * reason, we don't have to consider performance state of the subdomains
- * of genpd here.
+ * Traverse all powered-on subdomains within the domain. This can be
+ * done without any additional locking as the link->performance_state
+ * field is protected by the master genpd->lock, which is already taken.
+ *
+ * Also note that link->performance_state (subdomain's performance state
+ * requirement to master domain) is different from
+ * link->slave->performance_state (current performance state requirement
+ * of the devices/sub-domains of the subdomain) and so can have a
+ * different value.
*/
+ list_for_each_entry(link, &genpd->master_links, master_node) {
+ if (!genpd_status_on(link->slave))
+ continue;
+
+ if (link->performance_state > state)
+ state = link->performance_state;
+ }
+
+ if (state == genpd->performance_state)
+ return 0;

update_state:
- return _genpd_set_performance_state(genpd, state);
+ return _genpd_set_performance_state(genpd, state, depth);
}

/**
@@ -336,7 +403,7 @@ int dev_pm_genpd_set_performance_state(struct device *dev, unsigned int state)
prev = gpd_data->performance_state;
gpd_data->performance_state = state;

- ret = _genpd_reeval_performance_state(genpd, state);
+ ret = _genpd_reeval_performance_state(genpd, state, 0);
if (ret)
gpd_data->performance_state = prev;

@@ -346,7 +413,8 @@ int dev_pm_genpd_set_performance_state(struct device *dev, unsigned int state)
}
EXPORT_SYMBOL_GPL(dev_pm_genpd_set_performance_state);

-static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
+static int
+_genpd_power_on(struct generic_pm_domain *genpd, bool timed, int depth)
{
unsigned int state_idx = genpd->state_idx;
ktime_t time_start;
@@ -367,7 +435,8 @@ static int _genpd_power_on(struct generic_pm_domain *genpd, bool timed)
elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));

if (unlikely(genpd->set_performance_state)) {
- ret = genpd->set_performance_state(genpd, genpd->performance_state);
+ ret = _genpd_set_performance_state(genpd,
+ genpd->performance_state, depth);
if (ret) {
pr_warn("%s: Failed to set performance state %d (%d)\n",
genpd->name, genpd->performance_state, ret);
@@ -557,7 +626,7 @@ static int genpd_power_on(struct generic_pm_domain *genpd, unsigned int depth)
}
}

- ret = _genpd_power_on(genpd, true);
+ ret = _genpd_power_on(genpd, true, depth);
if (ret)
goto err;

@@ -962,7 +1031,7 @@ static void genpd_sync_power_on(struct generic_pm_domain *genpd, bool use_lock,
genpd_unlock(link->master);
}

- _genpd_power_on(genpd, false);
+ _genpd_power_on(genpd, false, depth);

genpd->status = GPD_STATE_ACTIVE;
}
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 9ad101362aef..dd364abb649a 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -136,6 +136,10 @@ struct gpd_link {
struct list_head master_node;
struct generic_pm_domain *slave;
struct list_head slave_node;
+
+ /* Sub-domain's per-master domain performance state */
+ unsigned int performance_state;
+ unsigned int prev_performance_state;
};

struct gpd_timing_data {
--
2.19.1.568.g152ad8e3369a