linux-toradex.git/include/linux/pm_runtime.h, branch v5.12-rc5

PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter

2020-11-16T17:37:01+00:00

In many case, we need to check return value of pm_runtime_get_sync, but
it brings a trouble to the usage counter processing. Many callers forget
to decrease the usage counter when it failed, which could resulted in
reference leak. It has been discussed a lot[0][1]. So we add a function
to deal with the usage counter for better coding.

[0]https://lkml.org/lkml/2020/6/14/88
[1]https://patchwork.ozlabs.org/project/linux-tegra/list/?series=178139
Signed-off-by: Zhang Qilong 
Acked-by: Rafael J. Wysocki  
Signed-off-by: Jakub Kicinski

PM: runtime: Drop pm_runtime_clean_up_links()

2020-11-02T17:14:07+00:00

After commit d12544fb2aa9 ("PM: runtime: Remove link state checks in
rpm_get/put_supplier()") nothing prevents the consumer device's
runtime PM from acquiring additional references to the supplier
device after pm_runtime_clean_up_links() has run (or even while it
is running), so calling this function from __device_release_driver()
may be pointless (or even harmful).

Moreover, it ignores stateless device links, so the runtime PM
handling of managed and stateless device links is inconsistent
because of it, so better get rid of it entirely.

Fixes: d12544fb2aa9 ("PM: runtime: Remove link state checks in rpm_get/put_supplier()")
Signed-off-by: Rafael J. Wysocki 
Cc: 5.1+  # 5.1+
Tested-by: Xiang Chen 
Reviewed-by: Greg Kroah-Hartman

PM: runtime: Drop runtime PM references to supplier on link removal

2020-11-02T17:14:07+00:00

While removing a device link, drop the supplier device's runtime PM
usage counter as many times as needed to drop all of the runtime PM
references to it from the consumer in addition to dropping the
consumer's link count.

Fixes: baa8809f6097 ("PM / runtime: Optimize the use of device links")
Signed-off-by: Rafael J. Wysocki 
Cc: 5.1+  # 5.1+
Tested-by: Xiang Chen 
Reviewed-by: Greg Kroah-Hartman

PM: runtime: Fix typo in pm_runtime_set_active() helper comment

2020-10-20T17:45:14+00:00

This patch is to fix typo in the comment of helper pm_runtime_set_active().

Signed-off-by: Bean Huo 
[ rjw: Subject edit ]
Signed-off-by: Rafael J. Wysocki

PM: runtime: Add kerneldoc comments to multiple helpers

2020-08-04T10:39:28+00:00

Add kerneldoc comments to multiple PM-runtime helper functions
defined as static inline wrappers around lower-level routines to
provide quick reference decumentation of their behavior.

Some of them are similar to each other with subtle differences only
and the behavior of some of them may appear as counter-intuitive, so
clarify all that to avoid confusion.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Alan Stern 
Reviewed-by: Sakari Ailus

PM: runtime: Replace pm_runtime_callbacks_present()

2020-05-29T16:03:12+00:00

The name of pm_runtime_callbacks_present() is confusing, because
it suggests that the device has PM-runtime callbacks if 'true' is
returned by that function, but in fact that may not be the case,
so replace it with pm_runtime_has_no_callbacks() which is not
ambiguous.

No functional impact.

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

PM: runtime: Add pm_runtime_get_if_active()

2020-03-04T10:01:18+00:00

pm_runtime_get_if_in_use() bumps up the PM-runtime usage count if it
is not equal to zero and the device's PM-runtime status is 'active'.
This works for drivers that do not use autoidle, but for those that
do, the function returns zero even when the device is active.

In order to maintain sane device state while the device is powered on
in the hope that it'll be needed, pm_runtime_get_if_active(dev, true)
returns a positive value if the device's PM-runtime status is 'active'
when it is called, in which case it also increments the device's usage
count.

If the second argument of pm_runtime_get_if_active() is 'false', the
function behaves just like pm_runtime_get_if_in_use(), so redefine
the latter as a wrapper around the former.

Signed-off-by: Sakari Ailus 
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 428

2019-06-05T15:37:16+00:00

Based on 1 normalized pattern(s):

  this file is released under the gplv2

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 68 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Armijn Hemel 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190114.292346262@linutronix.de
Signed-off-by: Greg Kroah-Hartman

Merge back earlier PM core material for v5.1.

2019-02-01T10:53:35+00:00

PM-runtime: Fix deadlock with ktime_get()

2019-01-30T21:49:06+00:00

A deadlock has been seen when swicthing clocksources which use
PM-runtime.  The call path is:

change_clocksource
    ...
    write_seqcount_begin
    ...
    timekeeping_update
        ...
        sh_cmt_clocksource_enable
            ...
            rpm_resume
                pm_runtime_mark_last_busy
                    ktime_get
                        do
                            read_seqcount_begin
                        while read_seqcount_retry
    ....
    write_seqcount_end

Although we should be safe because we haven't yet changed the
clocksource at that time, we can't do that because of seqcount
protection.

Use ktime_get_mono_fast_ns() instead which is lock safe for such
cases.

With ktime_get_mono_fast_ns, the timestamp is not guaranteed to be
monotonic across an update and as a result can goes backward.
According to update_fast_timekeeper() description: "In the worst
case, this can result is a slightly wrong timestamp (a few
nanoseconds)". For PM-runtime autosuspend, this means only that
the suspend decision may be slightly suboptimal.

Fixes: 8234f6734c5d ("PM-runtime: Switch autosuspend over to using hrtimers")
Reported-by: Biju Das 
Signed-off-by: Vincent Guittot 
Reviewed-by: Ulf Hansson 
Signed-off-by: Rafael J. Wysocki