linux-kernel - Re: [PATCH v2 6/7] counter: ftm-quaddec: Documentation: Add specific counter sysfs documentation

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Message-ID: <20190311123626.00004f70@huawei.com>
Date:   Mon, 11 Mar 2019 12:36:26 +0000
From:   Jonathan Cameron <jonathan.cameron@...wei.com>
To:     William Breathitt Gray <vilhelm.gray@...il.com>
CC:     Patrick Havelange <patrick.havelange@...ensium.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Shawn Guo <shawnguo@...nel.org>, Li Yang <leoyang.li@....com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Thierry Reding" <thierry.reding@...il.com>,
        Esben Haabendal <esben@...bendal.dk>,
        <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-pwm@...r.kernel.org>, <linuxppc-dev@...ts.ozlabs.org>,
        "Jonathan Cameron" <jic23@...nel.org>
Subject: Re: [PATCH v2 6/7] counter: ftm-quaddec: Documentation: Add
 specific counter sysfs documentation

On Thu, 7 Mar 2019 20:42:16 +0900
William Breathitt Gray <vilhelm.gray@...il.com> wrote:

> On Wed, Mar 06, 2019 at 12:12:07PM +0100, Patrick Havelange wrote:
> > This adds documentation for the specific prescaler entry.
> > 
> > Signed-off-by: Patrick Havelange <patrick.havelange@...ensium.com>
> > ---
> > Changes v2
> >  - Add doc for prescaler entry
> > ---
> >  .../ABI/testing/sysfs-bus-counter-ftm-quaddec    | 16 ++++++++++++++++
> >  1 file changed, 16 insertions(+)
> >  create mode 100644 Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec
> > 
> > diff --git a/Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec b/Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec
> > new file mode 100644
> > index 000000000000..2da629d6d485
> > --- /dev/null
> > +++ b/Documentation/ABI/testing/sysfs-bus-counter-ftm-quaddec
> > @@ -0,0 +1,16 @@
> > +What:		/sys/bus/counter/devices/counterX/countY/prescaler_available
> > +KernelVersion:	5.1
> > +Contact:	linux-iio@...r.kernel.org
> > +Description:
> > +		Discrete set of available values for the respective Count Y
> > +		configuration are listed in this file. Values are delimited by
> > +		newline characters.
> > +
> > +What:		/sys/bus/counter/devices/counterX/countY/prescaler
> > +KernelVersion:	5.1
> > +Contact:	linux-iio@...r.kernel.org
> > +Description:
> > +		Configure the prescaler value associated with Count Y.
> > +		On the FlexTimer, the counter clock source passes through a
> > +		prescaler that is a 7-bit counter. This acts like a clock
> > +		divider.
> > -- 
> > 2.19.1  
> 
> Hmm, prescalers seem common enough among counter devices to permit these
> attributes to be listed in the sysfs-bus-counter documentation file.
> However, I'd like to wait until we get another counter driver for a
> device with a prescaler before we make that move. From there, we'll have
> a better vantage point to determine a fitting standard prescaler
> attribute behavior.
> 
> So for now, we'll keep these attributes documented here in the
> sysfs-bus-counter-ftm-quaddec file, until the time comes to broach the
> discussion again.
Agreed. As long as the definition is sufficiently non-specific so it can be
moved later.  I'm not sure for example that the docs need to say that it is
a 7 bit counter. That should be apparent from prescaler_available - or at
least possible values should be which is all we need to know.

Jonathan
> 
> William Breathitt Gray