The generic PM domains framework currently doesn't work with devices
whose power.irq_safe flag is set, because runtime PM callbacks for
such devices are run with interrupts disabled and the callbacks
provided by the generic PM domains framework use domain mutexes
and may sleep. However, such devices very well may belong to
power domains on some systems, so the generic PM domains framework
should take them into account.
For this reason, modify the generic PM domains framework so that the
domain .power_off() and .power_on() callbacks are never executed for
a domain containing devices with power.irq_safe set, although the
.stop_device() and .start_device() callbacks are still run for them.
Additionally, introduce a flag allowing the creator of a
struct generic_pm_domain object to indicate that its .stop_device()
and .start_device() callbacks may be run in interrupt context
(might_sleep_if() triggers if that flag is not set and one of those
callbacks is run in interrupt context).
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Currently pm_genpd_runtime_resume() has to walk the list of devices
from the device's PM domain to find the corresponding device list
object containing the need_restore field to check if the driver's
.runtime_resume() callback should be executed for the device.
This is suboptimal and can be simplified by using power.sybsys_data
to store device information used by the generic PM domains code.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Since it is now possible for a PM domain to have multiple masters
instead of one parent, rename the "wait for parent" status to reflect
the new situation.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Currently, for a given generic PM domain there may be only one parent
domain (i.e. a PM domain it depends on). However, there is at least
one real-life case in which there should be two parents (masters) for
one PM domain (the A3RV domain on SH7372 turns out to depend on the
A4LC domain and it depends on the A4R domain and the same time). For
this reason, allow a PM domain to have multiple parents (masters) by
introducing objects representing links between PM domains.
The (logical) links between PM domains represent relationships in
which one domain is a master (i.e. it is depended on) and another
domain is a slave (i.e. it depends on the master) with the rule that
the slave cannot be powered on if the master is not powered on and
the master cannot be powered off if the slave is not powered off.
Each struct generic_pm_domain object representing a PM domain has
two lists of links, a list of links in which it is a master and
a list of links in which it is a slave. The first of these lists
replaces the list of subdomains and the second one is used in place
of the parent pointer.
Each link is represented by struct gpd_link object containing
pointers to the master and the slave and two struct list_head
members allowing it to hook into two lists (the master's list
of "master" links and the slave's list of "slave" links). This
allows the code to get to the link from each side (either from
the master or from the slave) and follow it in each direction.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
The next patch will make it possible for a generic PM domain to have
multiple parents (i.e. multiple PM domains it depends on). To
prepare for that change it is necessary to change pm_genpd_poweron()
so that it doesn't jump to the start label after running itself
recursively for the parent domain. For this purpose, introduce a new
PM domain status value GPD_STATE_WAIT_PARENT that will be set by
pm_genpd_poweron() before calling itself recursively for the parent
domain and modify the code in drivers/base/power/domain.c so that
the GPD_STATE_WAIT_PARENT status is guaranteed to be preserved during
the execution of pm_genpd_poweron() for the parent.
This change also causes pm_genpd_add_subdomain() and
pm_genpd_remove_subdomain() to wait for started pm_genpd_poweron() to
complete and allows pm_genpd_runtime_resume() to avoid dropping the
lock after powering on the PM domain.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Currently, pm_genpd_poweron() and pm_genpd_poweroff() need to take
the parent PM domain's lock in order to modify the parent's counter
of active subdomains in a nonracy way. This causes the locking to be
considerably complex and in fact is not necessary, because the
subdomain counters may be implemented as atomic fields and they
won't have to be modified under a lock.
Replace the unsigned in sd_count field in struct generic_pm_domain
by an atomic_t one and modify the code in drivers/base/power/domain.c
to take this change into account.
This patch doesn't change the locking yet, that is going to be done
in a separate subsequent patch.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Function genpd_queue_power_off_work() is not defined for
CONFIG_PM_RUNTIME, so pm_genpd_poweroff_unused() causes a build
error to happen in that case. Fix the problem by making
pm_genpd_poweroff_unused() depend on CONFIG_PM_RUNTIME too.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Make pd_power_down_a3rv() use genpd_queue_power_off_work() to queue
up the powering off of the A4LC domain to avoid queuing it up when
it is pending.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
Add a new function pm_genpd_poweroff_unused() queuing up the
execution of pm_genpd_poweroff() for every initialized generic PM
domain. Calling it will cause every generic PM domain without
devices in use to be powered off.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Magnus Damm <damm@opensource.se>
A deadlock may occur if one of the PM domains' .start_device() or
.stop_device() callbacks or a device driver's .runtime_suspend() or
.runtime_resume() callback executed by the core generic PM domain
code uses a "wrong" runtime PM helper function. This happens, for
example, if .runtime_resume() from one device's driver calls
pm_runtime_resume() for another device in the same PM domain.
A similar situation may take place if a device's parent is in the
same PM domain, in which case the runtime PM framework may execute
pm_genpd_runtime_resume() automatically for the parent (if it is
suspended at the moment). This, of course, is undesirable, so
the generic PM domains code should be modified to prevent it from
happening.
The runtime PM framework guarantees that pm_genpd_runtime_suspend()
and pm_genpd_runtime_resume() won't be executed in parallel for
the same device, so the generic PM domains code need not worry
about those cases. Still, it needs to prevent the other possible
race conditions between pm_genpd_runtime_suspend(),
pm_genpd_runtime_resume(), pm_genpd_poweron() and pm_genpd_poweroff()
from happening and it needs to avoid deadlocks at the same time.
To this end, modify the generic PM domains code to relax
synchronization rules so that:
* pm_genpd_poweron() doesn't wait for the PM domain status to
change from GPD_STATE_BUSY. If it finds that the status is
not GPD_STATE_POWER_OFF, it returns without powering the domain on
(it may modify the status depending on the circumstances).
* pm_genpd_poweroff() returns as soon as it finds that the PM
domain's status changed from GPD_STATE_BUSY after it's released
the PM domain's lock.
* pm_genpd_runtime_suspend() doesn't wait for the PM domain status
to change from GPD_STATE_BUSY after executing the domain's
.stop_device() callback and executes pm_genpd_poweroff() only
if pm_genpd_runtime_resume() is not executed in parallel.
* pm_genpd_runtime_resume() doesn't wait for the PM domain status
to change from GPD_STATE_BUSY after executing pm_genpd_poweron()
and sets the domain's status to GPD_STATE_BUSY and increments its
counter of resuming devices (introduced by this change) immediately
after acquiring the lock. The counter of resuming devices is then
decremented after executing __pm_genpd_runtime_resume() for the
device and the domain's status is reset to GPD_STATE_ACTIVE (unless
there are more resuming devices in the domain, in which case the
status remains GPD_STATE_BUSY).
This way, for example, if a device driver's .runtime_resume()
callback executes pm_runtime_resume() for another device in the same
PM domain, pm_genpd_poweron() called by pm_genpd_runtime_resume()
invoked by the runtime PM framework will not block and it will see
that there's nothing to do for it. Next, the PM domain's lock will
be acquired without waiting for its status to change from
GPD_STATE_BUSY and the device driver's .runtime_resume() callback
will be executed. In turn, if pm_runtime_suspend() is executed by
one device driver's .runtime_resume() callback for another device in
the same PM domain, pm_genpd_poweroff() executed by
pm_genpd_runtime_suspend() invoked by the runtime PM framework as a
result will notice that one of the devices in the domain is being
resumed, so it will return immediately.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Currently, the .start_device() and .stop_device() callbacks from
struct generic_pm_domain() as well as the device drivers' runtime PM
callbacks used by the generic PM domains code are executed under
the generic PM domain lock. This, unfortunately, is prone to
deadlocks, for example if a device and its parent are boths members
of the same PM domain. For this reason, it would be better if the
PM domains code didn't execute device callbacks under the lock.
Rework the locking in the generic PM domains code so that the lock
is dropped for the execution of device callbacks. To this end,
introduce PM domains states reflecting the current status of a PM
domain and such that the PM domain lock cannot be acquired if the
status is GPD_STATE_BUSY. Make threads attempting to acquire a PM
domain's lock wait until the status changes to either
GPD_STATE_ACTIVE or GPD_STATE_POWER_OFF.
This change by itself doesn't fix the deadlock problem mentioned
above, but the mechanism introduced by it will be used for for this
purpose by a subsequent patch.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
There is the problem how to handle devices set up to wake up the
system from sleep states during system-wide power transitions.
In some cases, those devices can be turned off entirely, because the
wakeup signals will be generated on their behalf anyway. In some
other cases, they will generate wakeup signals if their clocks are
stopped, but only if power is not removed from them. Finally, in
some cases, they can only generate wakeup signals if power is not
removed from them and their clocks are enabled.
To allow platform-specific code to decide whether or not to put
wakeup devices (and their PM domains) into low-power state during
system-wide transitions, such as system suspend, introduce a new
generic PM domain callback, .active_wakeup(), that will be used
during the "noirq" phase of system suspend and hibernation (after
image creation) to decide what to do with wakeup devices.
Specifically, if this callback is present and returns "true", the
generic PM domain code will not execute .stop_device() for the
given wakeup device and its PM domain won't be powered off.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Kevin Hilman <khilman@ti.com>
Make generic PM domains support system-wide power transitions
(system suspend and hibernation). Add suspend, resume, freeze, thaw,
poweroff and restore callbacks to be associated with struct
generic_pm_domain objects and make pm_genpd_init() use them as
appropriate.
The new callbacks do nothing for devices belonging to power domains
that were powered down at run time (before the transition). For the
other devices the action carried out depends on the type of the
transition. During system suspend the power domain .suspend()
callback executes pm_generic_suspend() for the device, while the
PM domain .suspend_noirq() callback runs pm_generic_suspend_noirq()
for it, stops it and eventually removes power from the PM domain it
belongs to (after all devices in the domain have been stopped and its
subdomains have been powered off).
During system resume the PM domain .resume_noirq() callback
restores power to the PM domain (when executed for it first time),
starts the device and executes pm_generic_resume_noirq() for it,
while the .resume() callback executes pm_generic_resume() for the
device. Finally, the .complete() callback executes pm_runtime_idle()
for the device which should put it back into the suspended state if
its runtime PM usage count is equal to zero at that time.
The actions carried out during hibernation and resume from it are
analogous to the ones described above.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Introduce common headers, helper functions and callbacks allowing
platforms to use simple generic power domains for runtime power
management.
Introduce struct generic_pm_domain to be used for representing
power domains that each contain a number of devices and may be
parent domains or subdomains with respect to other power domains.
Among other things, this structure includes callbacks to be
provided by platforms for performing specific tasks related to
power management (i.e. ->stop_device() may disable a device's
clocks, while ->start_device() may enable them, ->power_off() is
supposed to remove power from the entire power domain
and ->power_on() is supposed to restore it).
Introduce functions that can be used as power domain runtime PM
callbacks, pm_genpd_runtime_suspend() and pm_genpd_runtime_resume(),
as well as helper functions for the initialization of a power
domain represented by a struct generic_power_domain object,
adding a device to or removing a device from it and adding or
removing subdomains.
Introduce configuration option CONFIG_PM_GENERIC_DOMAINS to be
selected by the platforms that want to use the new code.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Reviewed-by: Kevin Hilman <khilman@ti.com>
