linux-kernel - Re: [PATCH 3/4] iio: adc: mediatek: SET_LATE_SYSTEM_SLEEP_PM

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Date:   Thu, 6 Jun 2019 16:46:00 +0100
From:   Jonathan Cameron <jonathan.cameron@...wei.com>
To:     Chun-Hung Wu <chun-hung.wu@...iatek.com>
CC:     Matthias Brugger <matthias.bgg@...il.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        <linux-iio@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <wsd_upstream@...iatek.com>,
        <peter.wang@...iatek.com>, <kuohong.wang@...iatek.com>,
        <jg_poxu@...iatek.com>, <stanley.chu@...iatek.com>
Subject: Re: [PATCH 3/4] iio: adc: mediatek: SET_LATE_SYSTEM_SLEEP_PM_OPS
 support

On Tue, 28 May 2019 18:59:56 +0800
Chun-Hung Wu <chun-hung.wu@...iatek.com> wrote:

> Hi Matthias:
> 
>   Thanks for your suggestion, I think device_links is a good way to
> make dependency of module's suspend/resume order.
> 
> Hi Jonathan:
> 
>   Is it ok to keep using late_suspend and early_resume, or do you think
> it's better to use device_links?
I think device links would be preferable as the reasoning becomes explicit.
As I understand them they are also a less fragile solution.

Thanks,

Jonathan

> 
> Thanks,
> Chun-Hung
> On Wed, 2019-05-22 at 18:28 +0200, Matthias Brugger wrote:
> > 
> > On 20/05/2019 08:03, Chun-Hung Wu wrote:  
> > > Hi Jonathan:
> > > 
> > >   Thanks for the prompt reply,
> > > 
> > > On Sat, 2019-05-18 at 11:35 +0100, Jonathan Cameron wrote:  
> > >> On Thu, 16 May 2019 16:10:46 +0800
> > >> Chun-Hung Wu <chun-hung.wu@...iatek.com> wrote:
> > >>  
> > >>>   Move suspend/resume to late_suspend and
> > >>> early_resume to gurantee users can use auxadc  
> > >> guarantee
> > >>  
> > > will fix it in next version.  
> > >>> driver at suspend/resume stage.  
> > >> No problem with the patch content, but we need a reason why they may
> > >> want to do so?  
> > > Our thermal drivers uses auxadc at suspend/resume stage.
> > > In order to avoid auxadc suspended prior to thermal driver,
> > > we move auxadc to late_suspend and early_resume.
> > >   
> > 
> > That sounds like a user of device_links [1] to me.
> > 
> > [1] https://www.kernel.org/doc/html/latest/driver-api/device_link.html
> >   
> > > Thanks,
> > > Chun-Hung  
> > >>
> > >> Thanks,
> > >>
> > >> Jonathan  
> > >>>
> > >>> Signed-off-by: Chun-Hung Wu <chun-hung.wu@...iatek.com>
> > >>> ---
> > >>>  drivers/iio/adc/mt6577_auxadc.c | 7 ++++---
> > >>>  1 file changed, 4 insertions(+), 3 deletions(-)
> > >>>
> > >>> diff --git a/drivers/iio/adc/mt6577_auxadc.c b/drivers/iio/adc/mt6577_auxadc.c
> > >>> index e1bdcc0..58d7cb2 100644
> > >>> --- a/drivers/iio/adc/mt6577_auxadc.c
> > >>> +++ b/drivers/iio/adc/mt6577_auxadc.c
> > >>> @@ -326,9 +326,10 @@ static int mt6577_auxadc_remove(struct platform_device *pdev)
> > >>>  	return 0;
> > >>>  }
> > >>>  
> > >>> -static SIMPLE_DEV_PM_OPS(mt6577_auxadc_pm_ops,
> > >>> -			 mt6577_auxadc_suspend,
> > >>> -			 mt6577_auxadc_resume);
> > >>> +static const struct dev_pm_ops mt6577_auxadc_pm_ops = {
> > >>> +	SET_LATE_SYSTEM_SLEEP_PM_OPS(mt6577_auxadc_suspend,
> > >>> +				     mt6577_auxadc_resume)
> > >>> +};
> > >>>  
> > >>>  static const struct of_device_id mt6577_auxadc_of_match[] = {
> > >>>  	{ .compatible = "mediatek,mt2701-auxadc", .data = &mt8173_compat},  
> > >>  
> > > 
> > >   
> 
>