linux-kernel - Re: [rtc-linux] Re: [PATCH 4/5] RTC: Add support for RTCs on Wolfson WM831x devices

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Date:	Mon, 10 Aug 2009 23:08:24 +0200
From:	Alessandro Zummo <alessandro.zummo@...ertech.it>
To:	rtc-linux@...glegroups.com
Cc:	broonie@...nsource.wolfsonmicro.com,
	Samuel Ortiz <sameo@...ux.intel.com>,
	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org
Subject: Re: [rtc-linux] Re: [PATCH 4/5] RTC: Add support for RTCs on
 Wolfson WM831x devices

On Mon, 10 Aug 2009 21:57:13 +0100
Mark Brown <broonie@...nsource.wolfsonmicro.com> wrote:

> 
> >  given you have your own include directory undef mfd/
> >  you might want to move those #defines there
> 
> Unlike the others these registers can't really be used outside of this
> driver - for the other drivers there's potential for at least platform
> specific code if not multiple drivers to use some or all of the register
> definitions.

 ack.
 
> > > +struct wm831x_rtc {
> > > +	struct wm831x *wm831x;
> > > +	struct rtc_device *rtc;
> > > +	int alarm_enabled;
> > > +	int per_irq;
> 
> >  are those tows int or unsigned int? 
> 
> I've just dropped per_irq, it's not needed anyway.
> 
> >  or maybe alarm_enabled could be :1 ?
> 
> Done, but it doesn't really buy us much given that there's nothing
> else to pack it with.

 ack.

> > > +/*
> > > + * Set current time and date in RTC
> > > + */
> > > +static int wm831x_rtc_settime(struct device *dev, struct rtc_time *tm)
> 
> >  isn't rtc_set_mmss more appropriate?
> 
> Hrm, I think so so I've made the change.  It's not a particularly
> discoverable API - the fact that there's no readback equivalent hides
> the fact that it's supposed to be an equivalent for settime.  Some
> documentation would really help here.

 you're right. there's one but it's still in my tree. will push it
 one day.

> 
> > > +	ret = wm831x_set_bits(wm831x_rtc->wm831x, WM831X_RTC_CONTROL,
> > > +			      WM831X_RTC_ALM_ENA, enable);
> > > +	if (ret != 0)
> > > +		dev_err(&pdev->dev, "Failed to update RTC alarm: %d\n", ret);
> > > +
> > > +	return 0;
> 
> >  always 0 ? (also below..)
> 
> Failing suspend and resume due to failure to disable the RTC alarm
> would be excessive - indeed, I'd expect the overwhelming majority of
> systems to function perfectly well with no suspend/resume support in the
> driver at all.  RTC alarms are infrequent relative to other
> suspend/resume events in typical systems but suspend is normally used
> fairly heavily to preserve battery (typical applications include things
> like MP3 players or phones).  Typically the error handling would at best
> cause more serious consequences than the original error and there's
> little chance the user will be able to even report the error.

 ack.

> > > +static int __init wm831x_rtc_init(void)
> > > +{
> > > +	return platform_driver_register(&wm831x_rtc_driver);
> 
> >  can you use platform_driver_probe() ?
> 
> No, this is a MFD accessed over slow buses and we can't guarantee that
> the device will be registered.
> 
> Fixed everything else, will repost tomorrow.

 here's my acked-by in advance, feel free to push the patch
 with the series.

 Acked-by: Alessandro Zummo <a.zummo@...ertech.it>

 

-- 

 Best regards,

 Alessandro Zummo,
  Tower Technologies - Torino, Italy

  http://www.towertech.it

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