PM: domains: Drop/restore performance state votes for devices at runtime PM
authorUlf Hansson <ulf.hansson@linaro.org>
Thu, 3 Jun 2021 09:34:37 +0000 (11:34 +0200)
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>
Fri, 11 Jun 2021 16:39:24 +0000 (18:39 +0200)
commit5937c3ce21228d33d2eb3287baa7e4cf6978dba9
tree0d6dec080ef9d2d7161b286e67b117ca6b7e603f
parentd97fe100ee0b36c5dd8013ffd70fe8fcdcabff2b
PM: domains: Drop/restore performance state votes for devices at runtime PM

A subsystem/driver that need to manage OPPs for its device, should
typically drop its vote for the OPP when the device becomes runtime
suspended. In this way, the corresponding aggregation of the performance
state votes that is managed in genpd for the attached PM domain, may find
that the aggregated vote can be decreased. Hence, it may allow genpd to set
the lower performance state for the PM domain, thus avoiding to waste
energy.

To accomplish this, typically a subsystem/driver would need to call
dev_pm_opp_set_rate|opp() for its device from its ->runtime_suspend()
callback, to drop the vote for the OPP. Accordingly, it needs another call
to dev_pm_opp_set_rate|opp() to restore the vote for the OPP from its
->runtime_resume() callback.

To avoid boilerplate code in subsystems/driver to deal with these things,
let's instead manage this internally in genpd.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
drivers/base/power/domain.c
include/linux/pm_domain.h