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SubjectRe: [PATCH] net/wireless: enable wiphy device to suspend/resume asynchronously
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On Mon, 2015-08-24 at 11:45 +0800, Fu, Zhonghui wrote:
>
> On 2015/8/17 16:46, Arend van Spriel wrote:
> > + Rafael
> >
> > On 08/17/2015 09:29 AM, Johannes Berg wrote:
> > > On Mon, 2015-08-17 at 09:48 +0800, Fu, Zhonghui wrote:
> > > >
> > > > The suspend/resume timing of wiphy device and related devices
> > > > will be
> > > > ensured by their parent/child relationship. So, enabling wiphy
> > > > device
> > > > to suspend/resume asynchronously does not change any
> > > > dependency. It
> > > > can only take advantage of multicore and improve system
> > > > suspend/resume speed.
> > > >
> > >
> > > You're going to have to explain that to me, because I don't see
> > > that.
> > > All I see is that when looking at a device, if async is possible,
> > > it
> > > gets added to an async work, and if async is not possible then it
> > > gets
> > > done immediately. Even putting aside the question of whether or
> > > not
> > > async is ordered or not (I don't know), if the wiphy is async and
> > > the
> > > PCI (or other bus) device isn't, then it seems they could get
> > > handled
> > > out of order, no? Or is there some magic code somewhere that I'm
> > > missing that explicitly waits for the async of the parent/child
> > > relationship?
> >
> > This patch got me worried as well. Can't find the magic either.
> > Maybe Rafael can give some hints here.
>
> "dpm_wait_for_children" function will be invoked in
> "__device_suspend", "__device_suspend_late", and
> "__device_suspend_noirq" functions to synchronize the child
> relationship. "dpm_wait" function will be invoked in
> "device_resume_noirq", "device_resume_early", and "device_resume"
> functions to synchronize the parent relationship. If two devices have
> parent/child relationship, but different suspend/resume mode(sync or
> async), this will have no impact to PM timing order between them.
> Because all devices will use "__device_suspend",
> "__device_suspend_late" ... functions to complete their PM
> transition.
>

Ok, good point. For the unaware here, can you please resend with a
commit message amended with some of this information?

thanks,
johannes


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