System suspend states and device driver suspend() callback

System suspend states and device driver suspend() callback

[Li Yang]

Hi Guys,

Is there a standard way for the device drivers to know if the system
is going to “standby” mode or “mem” mode when the suspend() callbacks
are called?

Regards,

Leo

Re: System suspend states and device driver suspend() callback

[Arend van Spriel]

On 08/16/2013 10:06 AM, Li Yang wrote:
> Hi Guys,
>
> Is there a standard way for the device drivers to know if the system
> is going to “standby” mode or “mem” mode when the suspend() callbacks
> are called?

what about implementing struct device_driver::suspend?

This is for driver level suspend operation, so not per-device.

> Regards,
>
> Leo
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Re: System suspend states and device driver suspend() callback

[Rafael J. Wysocki]

On Friday, August 16, 2013 04:06:26 PM Li Yang wrote:
> Hi Guys,
> 
> Is there a standard way for the device drivers to know if the system
> is going to “standby” mode or “mem” mode when the suspend() callbacks
> are called?

No, there's none.

What do you need that for?

Rafael

Re: System suspend states and device driver suspend() callback

[Li Yang-R58472]

在 2013-8-16，下午7:22，"Rafael J. Wysocki" <rjw@sisk.pl> 写道：

> On Friday, August 16, 2013 04:06:26 PM Li Yang wrote:
>> Hi Guys,
>> 
>> Is there a standard way for the device drivers to know if the system
>> is going to “standby” mode or “mem” mode when the suspend() callbacks
>> are called?
> 
> No, there's none.
> 
> What do you need that for?

Some chips like ours are putting the on-chip devices into different low power states when entering different system low power states.  When we enter system standby, on-chip devices are clock gated.  While entering suspend to ram, on-chip devices are power gated.  We want to driver to act differently too when entering different suspend states.

- Leo

> 
> Rafael
> 
> 

Re: System suspend states and device driver suspend() callback

[Li Yang-R58472]

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> On Friday, August 16, 2013 04:06:26 PM Li Yang wrote:
>> Hi Guys,
>> 
>> Is there a standard way for the device drivers to know if the system
>> is going to ¡°standby¡± mode or ¡°mem¡± mode when the suspend() callbacks
>> are called?
> 
> No, there's none.
> 
> What do you need that for?

Some chips like ours are putting the on-chip devices into different low power states when entering different system low power states.  When we enter system standby, on-chip devices are clock gated.  While entering suspend to ram, on-chip devices are power gated.  We want to driver to act differently too when entering different suspend states.

- Leo

> 
> Rafael
> 
> 
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Re: System suspend states and device driver suspend() callback

[Rafael J. Wysocki]

On Friday, August 16, 2013 05:13:42 PM Li Yang-R58472 wrote:
> 
> 在 2013-8-16，下午7:22，"Rafael J. Wysocki" <rjw@sisk.pl> 写道：
> 
> > On Friday, August 16, 2013 04:06:26 PM Li Yang wrote:
> >> Hi Guys,
> >> 
> >> Is there a standard way for the device drivers to know if the system
> >> is going to “standby” mode or “mem” mode when the suspend() callbacks
> >> are called?
> > 
> > No, there's none.
> > 
> > What do you need that for?
> 
> Some chips like ours are putting the on-chip devices into different low
> power states when entering different system low power states.  When we enter
> system standby, on-chip devices are clock gated.  While entering suspend to
> ram, on-chip devices are power gated.  We want to driver to act differently
> too when entering different suspend states.

Can you possibly use platform suspend operations to implement that (in analogy
with ACPI suspend operations)?

Rafael

Re: System suspend states and device driver suspend() callback

[Li Yang]

On Sat, Aug 17, 2013 at 7:53 AM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> On Friday, August 16, 2013 05:13:42 PM Li Yang-R58472 wrote:
>>
>> 在 2013-8-16，下午7:22，"Rafael J. Wysocki" <rjw@sisk.pl> 写道：
>>
>> > On Friday, August 16, 2013 04:06:26 PM Li Yang wrote:
>> >> Hi Guys,
>> >>
>> >> Is there a standard way for the device drivers to know if the system
>> >> is going to “standby” mode or “mem” mode when the suspend() callbacks
>> >> are called?
>> >
>> > No, there's none.
>> >
>> > What do you need that for?
>>
>> Some chips like ours are putting the on-chip devices into different low
>> power states when entering different system low power states.  When we enter
>> system standby, on-chip devices are clock gated.  While entering suspend to
>> ram, on-chip devices are power gated.  We want to driver to act differently
>> too when entering different suspend states.
>
> Can you possibly use platform suspend operations to implement that (in analogy
> with ACPI suspend operations)?

I agree it's best to get the state that the device will be in during
suspend from the platform code.  Will it be better to have a standard
interface to pass this information?  Given the fact that a single
device can be used by different platforms even different architecture
nowadays.  How about exposing some new callbacks from the
platform_suspend_ops for the driver to use?

Regards,
Leo