linux-kernel - Re: [PATCH 1/1] acer-wmi: switch driver to dev_pm

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Date:	Sun, 26 Jul 2009 16:28:48 -0400
From:	Arnaud Faucher <arnaud.faucher@...il.com>
To:	Carlos Corbacho <carlos@...angeworlds.co.uk>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-kernel@...r.kernel.org, "Rafael J. Wysocki" <rjw@...k.pl>,
	Frans Pop <elendil@...net.nl>,
	Manuel Lauss <manuel.lauss@...il.com>,
	Erik Ekman <erik@...o.se>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Subject: Re: [PATCH 1/1] acer-wmi: switch driver to dev_pm_ops

On dim, 2009-07-26 at 19:35 +0100, Carlos Corbacho wrote:
> On Sunday 26 July 2009 19:08:09 Dmitry Torokhov wrote:
> > On Sun, Jul 26, 2009 at 03:23:29PM +0100, Carlos Corbacho wrote:
> > > [Removing linux-mips from CC - I don't know why they'd be interested in
> > > an x86 only platform driver...]
> > >
> > > On Sunday 26 July 2009 14:53:33 Arnaud Faucher wrote:
> > > > Gets rid of the following warning:
> > > > Platform driver 'acer-wmi' needs updating - please use dev_pm_ops
> > > >
> > > > Take 2, thanks to Dmitry, Rafael and Frans for pointing out PM issue on
> > > > hibernation when using dev_pm_ops blindly.
> > > >
> > > > This patch was tested against suspendand hibernation (Acer mail led
> > > > status).
> > > >
> > > > Signed-off-by: Arnaud Faucher <arnaud.faucher@...il.com>
> > > > ---
> > > >  drivers/platform/x86/acer-wmi.c |   17 ++++++++++++-----
> > > >  1 files changed, 12 insertions(+), 5 deletions(-)
> > > >
> > > > diff --git a/drivers/platform/x86/acer-wmi.c
> > > > b/drivers/platform/x86/acer-wmi.c
> > > > index be2fd6f..29374bc 100644
> > > > --- a/drivers/platform/x86/acer-wmi.c
> > > > +++ b/drivers/platform/x86/acer-wmi.c
> > > > @@ -1152,8 +1152,7 @@ static int acer_platform_remove(struct
> > > > platform_device *device)
> > > >  	return 0;
> > > >  }
> > > >
> > > > -static int acer_platform_suspend(struct platform_device *dev,
> > > > -pm_message_t state)
> > > > +static int acer_platform_suspend(struct device *dev)
> > > >  {
> > > >  	u32 value;
> > > >  	struct acer_data *data = &interface->data;
> > > > @@ -1174,7 +1173,7 @@ pm_message_t state)
> > > >  	return 0;
> > > >  }
> > > >
> > > > -static int acer_platform_resume(struct platform_device *device)
> > > > +static int acer_platform_resume(struct device *dev)
> > > >  {
> > > >  	struct acer_data *data = &interface->data;
> > > >
> > > > @@ -1190,15 +1189,23 @@ static int acer_platform_resume(struct
> > > > platform_device *device)
> > > >  	return 0;
> > > >  }
> > > >
> > > > +static struct dev_pm_ops acer_platform_pm_ops = {
> > > > +	.suspend = acer_platform_suspend,
> > > > +	.resume = acer_platform_resume,
> > >
> > > Are these necessary? For suspend-to-RAM, I've never needed these. The old
> > > callbacks here were just for suspend-to-disk.
> >
> > That is not correct. Old suspend and resume callbacks were called for
> > both S2R and S2D. Whether it is actually needed for S2R I don't know but
> > looking at the code they should not hurt.
> 
> I'm aware they were called for S2RAM as well, but that was just a limitation 
> of the old calls - as I say, they're not needed for it (at least on my 
> hardware anyway).
> 

I was looking for similar functionality.

> > > > +	.freeze = acer_platform_suspend,
> > > > +	.thaw = acer_platform_resume,
> > >
> > > If we only need these callbacks for freeze & thaw, they should be
> > > rebamed.
> > >
> > > > +	.poweroff = acer_platform_suspend,
> > > > +	.restore = acer_platform_resume,
> > >
> > > What do poweroff and restore mean in this context. Do my comments above
> > > apply again (i.e. are the callbacks necessary here)?
> >
> > I don't think poweroff handler is needed.

After testing many combinations, I observed that I had to use that much
callbacks. For example, when omitting to wire .poweroff/.restore,
with .freeze/.thaw linked to suspend()/resume(), the state (of the mail
led) is not restored correctly after S2D.

> >
> > BTW, why so we retuen -ENOMEM from these methods if interface->data is
> > missing? I'd say we should not fail suspend resume in that case or if we
> > fail then with somethig like -EINVAL - we did not have mempry allocation
> > failure.
> 
> Ok.
> 
> -Carlos


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