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

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Date:	Wed, 1 Apr 2015 11:55:01 +0200
From:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:	Joe Perches <joe@...ches.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 31/03/2015 at 20:25:19 -0700, Joe Perches wrote :
> 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().
> 

As the issue may be sporadic, I would say that the reasoning behind the
patch is correct. Userspace is already aware that something went wrong
when reading and those debug messages are not adding any information.


-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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