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From: Stephen Boyd <sboyd@kernel.org>
To: <u.kleine-koenig@pengutronix.de>
Cc: Alexander Dahl <ada@thorsis.com>,
	Michael Turquette <mturquette@baylibre.com>,
	Rob Herring <robh+dt@kernel.org>,
	devicetree@vger.kernel.org, linux-clk@vger.kernel.org,
	kernel@pengutronix.de
Subject: Re: [PATCH v2] dt-bindings: clk: Make example a bit clearer
Date: Mon, 16 Sep 2019 13:13:16 -0700
Message-ID: <20190916201316.ED7EB20665@mail.kernel.org> (raw)
In-Reply-To: <20190911174948.sblu4qn44sfh3cyy@pengutronix.de>

(Sorry my MUA fails at utf8 encoding emails)

> On Wed, Sep 11, 2019 at 09:06:47AM -0700, Stephen Boyd wrote:
> > > diff --git a/Documentation/devicetree/bindings/clock/clock-bindings.txt b/Documentation/devicetree/bindings/clock/clock-bindings.txt
> > > index b646bbcf7f92..1d4942380918 100644
> > > --- a/Documentation/devicetree/bindings/clock/clock-bindings.txt
> > > +++ b/Documentation/devicetree/bindings/clock/clock-bindings.txt
> > > @@ -150,16 +150,18 @@ set to 0, or can be omitted if it is not followed by any non-zero entry.
> > >          compatible = "fsl,imx-uart";
> > >          reg = <0xa000 0x1000>;
> > >          ...
> > > -        clocks = <&osc 0>, <&pll 1>;
> > > -        clock-names = "baud", "register";
> > > +        clocks = ...
> > > +        clock-names = ...
> > 
> > I don't see the need for this change.
> 
> <&pll 1> is mentioned below. But it is not this instance that is
> relevant. So I suggested to get rid of it to not be a source of
> confusion. (But I guess you understood that.)

Yes.

> 
> > >          assigned-clocks = <&clkcon 0>, <&pll 2>;
> > > -        assigned-clock-parents = <&pll 2>;
> > > +        assigned-clock-parents = <&pll 1>;
> > >          assigned-clock-rates = <0>, <460800>;
> > >      };
> > >  
> > > -In this example the <&pll 2> clock is set as parent of clock <&clkcon 0> and
> > > -the <&pll 2> clock is assigned a frequency value of 460800 Hz.
> > > +In this example the <&pll 1> clock is set as parent of clock <&clkcon 0> and
> > > +the <&pll 2> clock is assigned a frequency value of 460800 Hz.  A parent
> > > +setting for <&pll 2> is omitted (end of list) and rate setting for <&clkcon 0>
> > > +is skipped because set to <0>.
> > 
> > Maybe you can comment that the "clocks" and "clock-names" properties
> > don't matter for assigned clk rates and parents.
> 
> Sure, a long text can explain this, but a maximal simple example is
> very beneficial, too.
> 

The paragraph at the start of "Assigned clock parents and rates" already
explains how these properties work. This patch isn't going to help if
the reader hasn't read that paragraph, so reordering things isn't
providing more clarity. If anything, I would clarify the description of
the example by indicating what parts of the example we're talking about
when explaining, i.e.

	In this example the <&pll 2> clock is set as parent of the
	<&clkcon 0> clock because the first clock specifier in the
	assigned-clocks property is <&clkcon 0> and that matches the
	first clock specifier in the assigned-clock-parents property.
	Similarly the <&pll 2> clock is assigned a frequency value of
	460800 Hz because the second frequency in the
	assigned-clock-rates property is 460800 Hz and that matches the
	second clock specifier in the assigned-clocks property <&pll 2>.


  reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-23 10:03 Alexander Dahl
2019-09-11 16:06 ` Stephen Boyd
2019-09-11 17:49   ` Uwe Kleine-König
2019-09-16 20:13     ` Stephen Boyd [this message]
2019-10-10 14:16       ` Alexander Dahl
2019-11-08 22:18         ` Stephen Boyd

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