Query: When will drv->poweroff() called

viresh kumar viresh.linux at gmail.com
Thu Feb 16 10:16:11 EST 2012

[Sorry for mailing again, earlier mail bounced on linux-pm list,
as i wasn't subscribed to it]

Hi Amit,

Can you please clear my doubt regarding calling of
hibernation_set_ops() for ARM SoC's?


On Mon, Feb 6, 2012 at 8:19 PM, Viresh Kumar <viresh.kumar at st.com> wrote:
> On 2/6/2012 5:37 PM, Rafael J. Wysocki wrote:
>> On Monday, February 06, 2012, Viresh Kumar wrote:
>>> >
>>> > Hi Guys,
>>> >
>>> > Sorry for asking this silly question, but i couldn't locate much
>>> > help for it in documentation, so asking it.
>>> >
>>> > We were testing hibernation for SPEAr13xx SoC family, based on
>>> > ARM Cortex a9.
>>> >
>>> > I observed that poweroff() callback of individual drivers are not
>>> > getting called at all, while we test hibernate.
>> They should be called in the last phase of hibernation, after the image
>> has been created and the system is going for "power off" (hance the
>> callback name).
>>> > I tried to go through the code to see what happened. It looked like
>>> > there should be call to hibernation_set_ops() for platforms that are
>>> > willing to get a call to poweroff() for their drivers.
>> That's correct.  The ->poweroff() callbacks are only executed if
>> hibernation_mode is equal to HIBERNATION_PLATFORM, which is not the
>> default.
>>> > Otherwise shutdown of the busses gets called, which is a completely
>>> > different path.
>>> >
>>> > There are many drivers today, that are registering poweroff() from dev_pm_ops
>>> > but are not doing bus specific shutdown stuff.
>>> >
>>> > Even i tried to look for hibernation_set_ops() in kernel, and only acpi
>>> > code is calling it.
>> That's correct too.
>>> > I didn't understood how other ARM Sub-Arch's are handling this.
>> Well, they are supposed to call hibernation_set_ops() and set the operations
>> appropriately.  Those operations may be empty routines if they don't need
>> to do anything, but they have to be defined.
> Hi Amit,
> Can you give some input on why none of the ARM platforms are calling
> this routine currently.

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