linux-kernel - Re: [PATCH 2/3] rtc: __rtc_read

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Date:	Tue, 31 Mar 2015 20:25:19 -0700
From:	Joe Perches <joe@...ches.com>
To:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc:	Aaro Koskinen <aaro.koskinen@....fi>,
	Alessandro Zummo <a.zummo@...ertech.it>,
	rtc-linux@...glegroups.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] rtc: __rtc_read_time: reduce log level

On Wed, 2015-04-01 at 05:21 +0200, Alexandre Belloni wrote:
> On 28/03/2015 at 23:09:35 +0200, Aaro Koskinen wrote :
> > __rtc_read_time logs should be debug logs instead of error logs.
> > 
> > For example, when the RTC clock is not set, it's not really useful
> > to print a kernel error log every time someone tries to read the clock:
> > 
> > 	~ # hwclock -r
> > 	[  604.508263] rtc rtc0: read_time: fail to read
> > 	hwclock: RTC_RD_TIME: Invalid argument
> > 
> > If there's a real error, it's likely that lower level or higher level
> > code will tell it anyway. Make these logs debug logs, and also print
> > the error code for the read failure.
> > 
> 
> That actually may be the only error message printed for some failures.
> Some RTCs don't print anything in case of error in their .read_time()
> and there are in-kernel users of rtc_read_time that simply bail out
> without printing anything or have a trace that is already at the debug
> level.
> 
> I would agree that this would need a better harmonization and I guess we
> can do that for now. I'll try to fix the in-kernel cases.

Maybe these should use dev_err_once().

> > diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
[]
> > @@ -31,13 +31,14 @@ static int __rtc_read_time(struct rtc_device *rtc, struct rtc_time *tm)
> >  		memset(tm, 0, sizeof(struct rtc_time));
> >  		err = rtc->ops->read_time(rtc->dev.parent, tm);
> >  		if (err < 0) {
> > -			dev_err(&rtc->dev, "read_time: fail to read\n");
> > +			dev_dbg(&rtc->dev, "read_time: fail to read: %d\n",
> > +				err);
> >  			return err;
> >  		}
> >  
> >  		err = rtc_valid_tm(tm);
> >  		if (err < 0)
> > -			dev_err(&rtc->dev, "read_time: rtc_time isn't valid\n");
> > +			dev_dbg(&rtc->dev, "read_time: rtc_time isn't valid\n");
> >  	}
> >  	return err;
> >  }



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