linux-kernel - [PATCH 1/2] PM / Runtime: fix autosuspend documentation

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Date:   Mon, 10 Apr 2017 13:38:24 +0200
From:   Johan Hovold <johan@...nel.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Alan Stern <stern@...land.harvard.edu>,
        Kevin Hilman <khilman@...libre.com>,
        Tony Lindgren <tony@...mide.com>,
        Ulf Hansson <ulf.hansson@...aro.org>, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Johan Hovold <johan@...nel.org>
Subject: [PATCH 1/2] PM / Runtime: fix autosuspend documentation

Update the autosuspend documentation which claimed that the autosuspend
delay is not taken into account when using the non-autosuspend helper
functions, something which is no longer true since commit d66e6db28df3
("PM / Runtime: Respect autosuspend when idle triggers suspend").

This specifically means that drivers must now disable autosuspend before
disabling runtime pm in probe error paths and remove callbacks if
pm_runtime_put_sync was being used to suspend the device before
returning. (If an idle callback can prevent suspend,
pm_runtime_put_sync_suspend must be used instead of pm_runtime_put_sync
as before.)

Also remove the claim that the autosuspend helpers behave "just like
the non-autosuspend counterparts", something which have never really
been true as some of the latter use idle notifications.

Signed-off-by: Johan Hovold <johan@...nel.org>
---
 Documentation/power/runtime_pm.txt | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
index 64546eb9a16a..56a13b865927 100644
--- a/Documentation/power/runtime_pm.txt
+++ b/Documentation/power/runtime_pm.txt
@@ -836,9 +836,8 @@ of the non-autosuspend counterparts:
 	Instead of: pm_runtime_put_sync   use: pm_runtime_put_sync_autosuspend.

 Drivers may also continue to use the non-autosuspend helper functions; they
-will behave normally, not taking the autosuspend delay into account.
-Similarly, if the power.use_autosuspend field isn't set then the autosuspend
-helper functions will behave just like the non-autosuspend counterparts.
+will behave normally, which means sometimes taking the autosuspend delay into
+account (see pm_runtime_idle).

 Under some circumstances a driver or subsystem may want to prevent a device
 from autosuspending immediately, even though the usage counter is zero and the
-- 
2.12.2