PM / Domains: Support for multiple states
Some hardware (eg. OMAP), has the ability to enter different low power
modes for a given power domain. This allows for more fine grained control
over the power state of the platform. As a typical example, some registers
of the hardware may be implemented with retention flip-flops and be able
to retain their state at lower voltages allowing for faster on/off
latencies and an increased window of opportunity to enter an intermediate
low power state other than "off"
When trying to set a power domain to off, the genpd governor will choose
the deepest state that will respect the qos constraints of all the devices
and sub-domains on the power domain. The state chosen by the governor is
saved in the "state_idx" field of the generic_pm_domain structure and
shall be used by the power_off and power_on callbacks to perform the
necessary actions to set the power domain into (and out of) the state
indicated by state_idx.
States must be declared in ascending order from shallowest to deepest,
deepest meaning the state which takes longer to enter and exit.
For platforms that don't declare any states, a single a single "off"
state is used. Once all platforms are converted to use the state array,
the legacy on/off latencies will be removed.
[ Lina: Modified genpd state initialization and remove use of
save_state_latency_ns in genpd timing data ]
Suggested-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
Signed-off-by: Axel Haslam <ahaslam+renesas@baylibre.com>
Acked-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_governor.c b/drivers/base/power/domain_governor.c
index 1e937ac..00a5436 100644
--- a/drivers/base/power/domain_governor.c
+++ b/drivers/base/power/domain_governor.c
@@ -98,7 +98,8 @@
*
* This routine must be executed under the PM domain's lock.
*/
-static bool default_power_down_ok(struct dev_pm_domain *pd)
+static bool __default_power_down_ok(struct dev_pm_domain *pd,
+ unsigned int state)
{
struct generic_pm_domain *genpd = pd_to_genpd(pd);
struct gpd_link *link;
@@ -106,27 +107,9 @@
s64 min_off_time_ns;
s64 off_on_time_ns;
- if (genpd->max_off_time_changed) {
- struct gpd_link *link;
+ off_on_time_ns = genpd->states[state].power_off_latency_ns +
+ genpd->states[state].power_on_latency_ns;
- /*
- * We have to invalidate the cached results for the masters, so
- * use the observation that default_power_down_ok() is not
- * going to be called for any master until this instance
- * returns.
- */
- list_for_each_entry(link, &genpd->slave_links, slave_node)
- link->master->max_off_time_changed = true;
-
- genpd->max_off_time_changed = false;
- genpd->cached_power_down_ok = false;
- genpd->max_off_time_ns = -1;
- } else {
- return genpd->cached_power_down_ok;
- }
-
- off_on_time_ns = genpd->power_off_latency_ns +
- genpd->power_on_latency_ns;
min_off_time_ns = -1;
/*
@@ -186,8 +169,6 @@
min_off_time_ns = constraint_ns;
}
- genpd->cached_power_down_ok = true;
-
/*
* If the computed minimum device off time is negative, there are no
* latency constraints, so the domain can spend arbitrary time in the
@@ -201,10 +182,45 @@
* time and the time needed to turn the domain on is the maximum
* theoretical time this domain can spend in the "off" state.
*/
- genpd->max_off_time_ns = min_off_time_ns - genpd->power_on_latency_ns;
+ genpd->max_off_time_ns = min_off_time_ns -
+ genpd->states[state].power_on_latency_ns;
return true;
}
+static bool default_power_down_ok(struct dev_pm_domain *pd)
+{
+ struct generic_pm_domain *genpd = pd_to_genpd(pd);
+ struct gpd_link *link;
+
+ if (!genpd->max_off_time_changed)
+ return genpd->cached_power_down_ok;
+
+ /*
+ * We have to invalidate the cached results for the masters, so
+ * use the observation that default_power_down_ok() is not
+ * going to be called for any master until this instance
+ * returns.
+ */
+ list_for_each_entry(link, &genpd->slave_links, slave_node)
+ link->master->max_off_time_changed = true;
+
+ genpd->max_off_time_ns = -1;
+ genpd->max_off_time_changed = false;
+ genpd->cached_power_down_ok = true;
+ genpd->state_idx = genpd->state_count - 1;
+
+ /* Find a state to power down to, starting from the deepest. */
+ while (!__default_power_down_ok(pd, genpd->state_idx)) {
+ if (genpd->state_idx == 0) {
+ genpd->cached_power_down_ok = false;
+ break;
+ }
+ genpd->state_idx--;
+ }
+
+ return genpd->cached_power_down_ok;
+}
+
static bool always_on_power_down_ok(struct dev_pm_domain *domain)
{
return false;