linux-kernel - Re: [PATCH 4/4] rtc: ds1307: add frequency-test property to check calibration on m41txx

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Message-ID: <CAL_JsqKb9aLxjQbOc1PFRQhbVL2a3Ti2oJ8Gm8Ojn0a39LxajA@mail.gmail.com>
Date:   Tue, 8 May 2018 12:44:12 -0500
From:   Rob Herring <robh+dt@...nel.org>
To:     Giulio Benetti <giulio.benetti@...ronovasrl.com>
Cc:     Alessandro Zummo <a.zummo@...ertech.it>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Mark Rutland <mark.rutland@....com>,
        "open list:REAL TIME CLOCK (RTC) SUBSYSTEM" 
        <linux-rtc@...r.kernel.org>, devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] rtc: ds1307: add frequency-test property to check
 calibration on m41txx

On Tue, May 8, 2018 at 9:56 AM, Giulio Benetti
<giulio.benetti@...ronovasrl.com> wrote:
> On m41txx you can enable open-drain OUT pin to check if calibration is ok.
> Enabling OUT pin with frequency-test bool property, OUT pin will tick
> 512 times faster than 1s tick base.
>
> Enable FT bit on CONTROL register if calibration is active.

A DT is (or should be) a pretty static thing, so I don't think this
belongs. A kernel command line option (via module params) or a
sysfs/debugfs file would make more sense IMO.

Rob