linux-stable.git/include/linux/pm_domain.h, branch v5.13.2

PM: domains: use device's next wakeup to determine domain idle state

2021-01-22T16:08:28+00:00

Currently, a PM domain's idle state is determined based on whether the
QoS requirements are met. However, even entering an idle state may waste
power if the minimum residency requirements aren't fulfilled.

CPU PM domains use the next timer wakeup for the CPUs in the domain to
determine the sleep duration of the domain. This is compared with the
idle state residencies to determine the optimal idle state. For other PM
domains, determining the sleep length is not that straight forward. But
if the device's next_event is available, we can use that to determine
the sleep duration of the PM domain.

Let's update the domain governor logic to check for idle state residency
based on the next wakeup of devices as well as QoS constraints. But
since, not all domains may contain devices capable of specifying the
next wakeup, let's enable this additional check only if specified by the
domain's flags when initializing the domain.

Signed-off-by: Lina Iyer 
Reviewed-by: Ulf Hansson 
Signed-off-by: Rafael J. Wysocki

PM: domains: inform PM domain of a device's next wakeup

2021-01-22T16:08:27+00:00

Some devices may have a predictable interrupt pattern while executing
usecases. An example would be the VSYNC interrupt associated with
display devices. A 60 Hz display could cause a interrupt every 16 ms. If
the device were in a PM domain, the domain would need to be powered up
for device to resume and handle the interrupt.

Entering a domain idle state saves power, only if the residency of the
idle state is met. Without knowing the idle duration of the domain, the
governor would just choose the deepest idle state that matches the QoS
requirements. The domain might be powered off just as the device is
expecting to wake up. If devices could inform PM frameworks of their
next event, the parent PM domain's idle duration can be determined.

So let's add the dev_pm_genpd_set_next_wakeup() API for the device to
inform PM domains of the impending wakeup. This information will be the
domain governor to determine the best idle state given the wakeup.

Signed-off-by: Lina Iyer 
Reviewed-by: Ulf Hansson 
Signed-off-by: Rafael J. Wysocki

Merge branches 'pm-sleep', 'pm-acpi', 'pm-domains' and 'powercap'

2020-12-15T14:26:14+00:00

* pm-sleep:
  PM: sleep: Add dev_wakeup_path() helper
  PM / suspend: fix kernel-doc markup
  PM: sleep: Print driver flags for all devices during suspend/resume

* pm-acpi:
  PM: ACPI: Refresh wakeup device power configuration every time
  PM: ACPI: PCI: Drop acpi_pm_set_bridge_wakeup()
  PM: ACPI: reboot: Use S5 for reboot

* pm-domains:
  PM: domains: create debugfs nodes when adding power domains
  PM: domains: replace -ENOTSUPP with -EOPNOTSUPP

* powercap:
  powercap: Adjust printing the constraint name with new line
  powercap: RAPL: Add AMD Fam19h RAPL support
  powercap: Add AMD Fam17h RAPL support
  powercap/intel_rapl_msr: Convert rapl_msr_priv into pointer
  x86/msr-index: sort AMD RAPL MSRs by address

PM: domains: replace -ENOTSUPP with -EOPNOTSUPP

2020-11-23T17:41:28+00:00

While submitting a patch to add next_wakeup, checkpatch reported this -

WARNING: ENOTSUPP is not a SUSV4 error code, prefer EOPNOTSUPP
+       return -ENOTSUPP;

Address the above warning in other functions in pm_domain.h.

Reviewed-by: Ulf Hansson 
Signed-off-by: Lina Iyer 
Signed-off-by: Rafael J. Wysocki

PM: domains: Rename pm_genpd_syscore_poweroff|poweron()

2020-11-10T19:42:01+00:00

To better describe what the pm_genpd_syscore_poweroff|poweron() functions
actually do, let's rename them to dev_pm_genpd_suspend|resume() and update
the rather few callers of them accordingly (a couple of clocksource
drivers).

Moreover, let's take the opportunity to add some documentation of these
exported functions, as that is currently missing.

Signed-off-by: Ulf Hansson 
Signed-off-by: Rafael J. Wysocki

PM: domains: enable domain idle state accounting

2020-10-16T15:53:22+00:00

To enable better debug of PM domains, keep a track of successful
and failing attempts to enter each domain idle state.

This statistics are exported in debugfs when reading the
idle_states node associated with each PM domain.

Signed-off-by: Lina Iyer 
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki

PM: domains: Add support for PM domain on/off notifiers for genpd

2020-10-16T15:39:06+00:00

A device may have specific HW constraints that must be obeyed to, before
its corresponding PM domain (genpd) can be powered off - and vice verse at
power on. These constraints can't be managed through the regular runtime PM
based deployment for a device, because the access pattern for it, isn't
always request based. In other words, using the runtime PM callbacks to
deal with the constraints doesn't work for these cases.

For these reasons, let's instead add a PM domain power on/off notification
mechanism to genpd. To add/remove a notifier for a device, the device must
already have been attached to the genpd, which also means that it needs to
be a part of the PM domain topology.

To add/remove a notifier, let's introduce two genpd specific functions:
 - dev_pm_genpd_add|remove_notifier()

Note that, to further clarify when genpd power on/off notifiers may be
used, one can compare with the existing CPU_CLUSTER_PM_ENTER|EXIT
notifiers. In the long run, the genpd power on/off notifiers should be able
to replace them, but that requires additional genpd based platform support
for the current users.

Signed-off-by: Ulf Hansson 
Tested-by: Lina Iyer 
Signed-off-by: Rafael J. Wysocki

PM: domains: Rename power state enums for genpd

2020-10-02T17:15:16+00:00

To clarify the code a bit, let's rename GPD_STATE_ACTIVE into
GENPD_STATE_ON and GPD_STATE_POWER_OFF to GENPD_STATE_OFF.

Signed-off-by: Ulf Hansson 
[ rjw: Subject edit ]
Signed-off-by: Rafael J. Wysocki

PM: domains: Restore comment indentation for generic_pm_domain.child_links

2020-07-14T13:14:27+00:00

The rename of generic_pm_domain.slave_links to
generic_pm_domain.child_links accidentally dropped the TAB to align the
member's comment.  Re-add the lost TAB to restore indentation.

Fixes: 8d87ae48ced2dffd ("PM: domains: Fix up terminology with parent/child")
Signed-off-by: Geert Uytterhoeven 
[ rjw: Minor subject edit ]
Signed-off-by: Rafael J. Wysocki

PM: domains: Fix up terminology with parent/child

2020-07-09T12:24:00+00:00

The genpd infrastructure uses the terms master/slave, but such uses have
no external exposures (not even in Documentation/driver-api/pm/*) and are
not mandated by nor associated with any external specifications. Change
the language used through-out to parent/child.

There was one possible exception in the debugfs node
"pm_genpd/pm_genpd_summary" but its path has no hits outside of the
kernel itself when performing a code search[1], and it seems even this
single usage has been non-functional since it was introduced due to a
typo in the Python ("apend" instead of correct "append"). Fix the typo
while we're at it.

Link: https://codesearch.debian.net/ # [1]
Signed-off-by: Kees Cook 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Kieran Bingham 
Signed-off-by: Rafael J. Wysocki