Re: [PATCH 09/13] ARM: dts: mediatek: Enable clock support for Mediatek MT8135.

From: Sascha Hauer <s.hauer@pengutronix.de>
To: Russell King - ARM Linux <linux@arm.linux.org.uk>
Cc: "James Liao" <jamesjj.liao@mediatek.com>,
	"Mike Turquette" <mturquette@linaro.org>,
	"YH Chen (陳昱豪)" <yh.chen@mediatek.com>,
	linux-kernel@vger.kernel.org,
	"Henry Chen" <henryc.chen@mediatek.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	kernel@pengutronix.de,
	"Matthias Brugger" <matthias.bgg@gmail.com>,
	"Yingjoe Chen (陳英洲)" <Yingjoe.Chen@mediatek.com>,
	"Eddie Huang" <eddie.huang@mediatek.com>,
	"Lee Jones" <lee.jones@linaro.org>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 09/13] ARM: dts: mediatek: Enable clock support for Mediatek MT8135.
Date: Mon, 9 Feb 2015 12:44:03 +0100	[thread overview]
Message-ID: <20150209114403.GV12209@pengutronix.de> (raw)
In-Reply-To: <20150209112721.GG8656@n2100.arm.linux.org.uk>

On Mon, Feb 09, 2015 at 11:27:21AM +0000, Russell King - ARM Linux wrote:
> On Mon, Feb 09, 2015 at 12:25:00PM +0100, Sascha Hauer wrote:
> > On Mon, Feb 09, 2015 at 10:51:34AM +0000, Russell King - ARM Linux wrote:
> > > On Mon, Feb 09, 2015 at 11:47:21AM +0100, Sascha Hauer wrote:
> > > > From: James Liao <jamesjj.liao@mediatek.com>
> > > > 
> > > > This patch adds MT8135 clock controllers into device tree.
> > > > @@ -86,6 +87,18 @@
> > > >  			clock-frequency = <32000>;
> > > >  			#clock-cells = <0>;
> > > >  		};
> > > > +
> > > > +		clk_null: clk_null {
> > > > +			compatible = "fixed-clock";
> > > > +			#clock-cells = <0>;
> > > > +			clock-frequency = <0>;
> > > > +		};
> > > > +
> > > > +		clk26m: clk26m {
> > > > +			compatible = "fixed-clock";
> > > > +			#clock-cells = <0>;
> > > > +			clock-frequency = <26000000>;
> > > > +		};
> > > 
> > > Is this supposed to be here?
> > 
> > The clock support needs at least the clk26m clk. Do you think it should
> > be in another patch or not present at all?
> 
> I didn't see anything which referenced either clk_null or clk26m in this
> patch.  My main concern was that clk_null, but my concern grew when I
> found that clk26m wasn't referenced either.
> 
> If the MT8135 needs it, shouldn't something in its description reference
> this clock?

It's used in the code. The mt8135 clk code directly uses the names of
these three clocks as parent_names.

Sascha

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