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From: thierry.reding@gmail•com (Thierry Reding)
To: linux-arm-kernel@lists•infradead.org
Subject: [RESEND PATCH v2] thermal: tango: add resume support
Date: Mon, 18 Jul 2016 12:13:38 +0200	[thread overview]
Message-ID: <20160718101338.GB422@ulmo.ba.sec> (raw)
In-Reply-To: <7689133.3ycKRvbtrh@wuerfel>

On Mon, Jul 18, 2016 at 12:09:39PM +0200, Arnd Bergmann wrote:
> On Monday, July 18, 2016 11:33:28 AM CEST Thierry Reding wrote:
> 
> > > +
> > > +     return 0;
> > > +}
> > > +
> > > +static SIMPLE_DEV_PM_OPS(tango_thermal_pm, NULL, tango_thermal_resume);
> > > +
> > > +#define DEV_PM_OPS   &tango_thermal_pm
> > > +#else
> > > +#define DEV_PM_OPS   NULL
> > > +#endif
> > 
> > In my experience it's often not useful to #ifdef the struct pm_ops.
> > These days you almost certainly want PM enabled, and the conditional
> > doesn't save you all that much in the first place, because it's not
> > unlikely for this to fit into some of the space that would be padded
> > out anyway.
> 
> This will also generate a warning when CONFIG_PM_SLEEP is not set.
> Better write this as
> 
> #define DEV_PM_OPS (IS_ENABLED(CONFIG_PM_SLEEP) ? &tango_thermal_pm : NULL)
> 
> so the compiler can drop the variable definition when it's not
> needed.

My suggestion was to define tango_thermal_pm unconditionally to avoid
any of these tricks. For any real use-case in which the 92 bytes for the
struct dev_pm_ops would matter you most likely want PM_SLEEP anyway, so
I don't really see why we would even want to make it optional.

> > As a side-note, I've noticed that this driver has the following
> > dependencies:
> > 
> >         depends on ARCH_TANGO || COMPILE_TEST
> > 
> > which, last I checked, is probably going to fail on some architectures
> > because you need at least another one on HAS_IOMEM (for readl() and
> > writel()). That's a pre-existing problem, of course, so should be fixed
> > in a separate patch.
> 
> No need, we just merged a patch to no longer allow COMPILE_TEST on
> arch/um/, so we can safely rely on MMIO to be available for COMPILE_TEST.

I thought at least S390 didn't have readl() and writel() either, at
least when PCI wasn't enabled, or some such.

Thierry
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  reply	other threads:[~2016-07-18 10:13 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-28 11:37 [RESEND PATCH v2] thermal: tango: add resume support Mason
2016-07-18  9:33 ` Thierry Reding
2016-07-18 10:09   ` Arnd Bergmann
2016-07-18 10:13     ` Thierry Reding [this message]
2016-07-18 11:10       ` Arnd Bergmann
2016-07-18 11:28         ` Thierry Reding
2016-07-18 12:21 ` [PATCH v3] " Mason
2016-07-20 10:50   ` Thierry Reding
2016-07-22 22:00   ` Kevin Hilman
2016-07-25  8:18     ` Mason
2016-07-25  8:52       ` Arnd Bergmann
2016-07-25  9:48         ` Mason
2016-07-26 12:13           ` Arnd Bergmann
2016-08-19 11:29             ` Zhang Rui
2016-08-22 21:00               ` Arnd Bergmann
2016-08-24  8:25                 ` Zhang Rui
2016-08-24  8:32                   ` Arnd Bergmann
2016-08-24 15:12                     ` Mason
2016-09-02 13:17 ` [PATCH v4] " Marc Gonzalez
2016-09-02 20:54   ` Kevin Hilman

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