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

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Message-Id: <1248648663.3718.7.camel@green>
Date:	Sun, 26 Jul 2009 18:51:03 -0400
From:	Arnaud Faucher <arnaud.faucher@...il.com>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Carlos Corbacho <carlos@...angeworlds.co.uk>,
	"linux-kernel@...r.kernel.org" <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 14:33 -0700, Dmitry Torokhov wrote:
> On Jul 26, 2009, at 1:28 PM, Arnaud Faucher <arnaud.faucher@...il.com>  
> wrote:
> 
> > 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.
> 
> 
> Have you tried with just 3 - freeze, thaw and restore?
> 

State restoration seems to be OK with only those three ones (tested
against both S2RAM and S2D on my Acer Aspire 5680).

BTW, in the "struct dev_pm_ops" documentation, it would be interesting
to know which callback sequence occurs in case of S2RAM and S2D events.


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