Re: [PATCH V3] PM / Runtime: Respect autosuspend when idle triggers suspend

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On 16 October 2013 02:21, Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:
> On Tuesday, October 15, 2013 04:43:38 PM Alan Stern wrote:
>> On Tue, 15 Oct 2013, Ulf Hansson wrote:
>>
>> > For devices which don't have a .runtime_idle callback or if it returns
>> > 0, rpm_idle will end up in triggering a call to rpm_suspend, thus
>> > trying to carry out a runtime_suspend directly from runtime_idle.
>> >
>> > In the above situation we want to respect devices which has enabled
>> > autosuspend, we therfore append the flag sent to rpm_suspend with
>> > RPM_AUTO.
>> >
>> > Do note that drivers still needs to update the device last busy mark,
>> > to control the delay for this circumstance.
>> >
>> > Updated runtime PM documentation accordingly.
>> >
>> > Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
>> > Cc: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
>> > Cc: Kevin Hilman <khilman@xxxxxxxxxx>
>> > Cc: Rob Landley <rob@xxxxxxxxxxx>
>> > Cc: Chris Ball <cjb@xxxxxxxxxx>
>> > Cc: linux-mmc@xxxxxxxxxxxxxxx
>> > Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
>> > Acked-by: Kevin Hilman <khilman@xxxxxxxxxx>
>> > ---
>> >  Documentation/power/runtime_pm.txt |   14 ++++++++------
>> >  drivers/base/power/runtime.c       |    5 +++--
>> >  2 files changed, 11 insertions(+), 8 deletions(-)
>> >
>> > diff --git a/Documentation/power/runtime_pm.txt b/Documentation/power/runtime_pm.txt
>> > index 71d8fe4..0f54333 100644
>> > --- a/Documentation/power/runtime_pm.txt
>> > +++ b/Documentation/power/runtime_pm.txt
>> > @@ -145,11 +145,13 @@ The action performed by the idle callback is totally dependent on the subsystem
>> >  if the device can be suspended (i.e. if all of the conditions necessary for
>> >  suspending the device are satisfied) and to queue up a suspend request for the
>> >  device in that case.  If there is no idle callback, or if the callback returns
>> > -0, then the PM core will attempt to carry out a runtime suspend of the device;
>> > -in essence, it will call pm_runtime_suspend() directly.  To prevent this (for
>> > -example, if the callback routine has started a delayed suspend), the routine
>> > -should return a non-zero value.  Negative error return codes are ignored by the
>> > -PM core.
>> > +0, then the PM core will attempt to carry out a runtime suspend of the device,
>> > +also respecting devices configured for autosuspend.  In essence this means a
>> > +call to pm_runtime_autosuspend() (do note that drivers needs to update the
>> > +device last busy mark, pm_runtime_mark_last_busy(), to control the delay under
>> > +this circumstance).  To prevent this (for example, if the callback routine has
>> > +started a delayed suspend), the routine must return a non-zero value.  Negative
>> > +error return codes are ignored by the PM core.
>> >
>> >  The helper functions provided by the PM core, described in Section 4, guarantee
>> >  that the following constraints are met with respect to runtime PM callbacks for
>> > @@ -308,7 +310,7 @@ drivers/base/power/runtime.c and include/linux/pm_runtime.h:
>> >      - execute the subsystem-level idle callback for the device; returns an
>> >        error code on failure, where -EINPROGRESS means that ->runtime_idle() is
>> >        already being executed; if there is no callback or the callback returns 0
>> > -      then run pm_runtime_suspend(dev) and return its result
>> > +      then run pm_runtime_autosuspend(dev) and return its result
>> >
>> >    int pm_runtime_suspend(struct device *dev);
>> >      - execute the subsystem-level suspend callback for the device; returns 0 on
>> > diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
>> > index 268a350..72e00e6 100644
>> > --- a/drivers/base/power/runtime.c
>> > +++ b/drivers/base/power/runtime.c
>> > @@ -258,7 +258,8 @@ static int __rpm_callback(int (*cb)(struct device *), struct device *dev)
>> >   * Check if the device's runtime PM status allows it to be suspended.  If
>> >   * another idle notification has been started earlier, return immediately.  If
>> >   * the RPM_ASYNC flag is set then queue an idle-notification request; otherwise
>> > - * run the ->runtime_idle() callback directly.
>> > + * run the ->runtime_idle() callback directly. If the ->runtime_idle callback
>> > + * doesn't exist or if it returns 0, call rpm_suspend with the RPM_AUTO flag.
>> >   *
>> >   * This function must be called under dev->power.lock with interrupts disabled.
>> >   */
>> > @@ -331,7 +332,7 @@ static int rpm_idle(struct device *dev, int rpmflags)
>> >
>> >   out:
>> >     trace_rpm_return_int(dev, _THIS_IP_, retval);
>> > -   return retval ? retval : rpm_suspend(dev, rpmflags);
>> > +   return retval ? retval : rpm_suspend(dev, rpmflags | RPM_AUTO);
>> >  }
>> >
>> >  /**
>>
>> Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
>
> I've queued up this patch for 3.13.
>
> Thanks!

Rafael, Alan - thanks a lot for helping out around this patch!

Kind regards
Ulf Hansson

>
> --
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.
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