linux-kernel - Re: [PATCH 1/3] arm64: dts: actions: add s900 clock controller nodes

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Date:   Sat, 4 Nov 2017 14:32:33 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Rob Herring <robh@...nel.org>
Cc:     mturquette@...libre.com, sboyd@...eaurora.org, afaerber@...e.de,
        mark.rutland@....com, linux-kernel@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org, davem@...emloft.net,
        mchehab@...nel.org, rdunlap@...radead.org,
        daniel.thompson@...aro.org, amit.kucheria@...aro.org,
        liuwei@...ions-semi.com
Subject: Re: [PATCH 1/3] arm64: dts: actions: add s900 clock controller nodes

Hi Rob,
On Wed, Nov 01, 2017 at 07:06:16PM -0500, Rob Herring wrote:
> On Wed, Nov 01, 2017 at 01:24:21AM +0530, Manivannan Sadhasivam wrote:
> > This patch adds clock controller nodes for Actions Semi s900 SoC
> > 
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > ---
> >  arch/arm64/boot/dts/actions/s900.dtsi | 19 +++++++++++++++++++
> >  1 file changed, 19 insertions(+)
> > 
> > diff --git a/arch/arm64/boot/dts/actions/s900.dtsi b/arch/arm64/boot/dts/actions/s900.dtsi
> > index 11406f6..c099ef1 100644
> > --- a/arch/arm64/boot/dts/actions/s900.dtsi
> > +++ b/arch/arm64/boot/dts/actions/s900.dtsi
> > @@ -5,6 +5,7 @@
> >   */
> >  
> >  #include <dt-bindings/interrupt-controller/arm-gic.h>
> > +#include <dt-bindings/clock/actions,s900-clock.h>
> >  
> >  / {
> >  	compatible = "actions,s900";
> > @@ -88,6 +89,24 @@
> >  		#clock-cells = <0>;
> >  	};
> >  
> > +	losc: losc {
> > +		compatible = "fixed-clock";
> > +		clock-frequency = <32768>;
> > +		#clock-cells = <0>;
> > +	};
> > +
> > +	diff_24M: diff_24M {
> > +		compatible = "fixed-clock";
> > +		clock-frequency = <24000000>;
> > +		#clock-cells = <0>;
> > +	};
> 
> These 2 are inputs to the clock ctrlr? The clock controller should have 
> a clocks property then.
> 
Actually losc and hosc (already defined) are the sources to the clock
controller. There isn't much documentation about diff_24M clock which
seems to be only sourcing eDP. Since, the vendor driver defined these
3 clocks (losc, hosc, diff_24M) as fixed rate clocks I have added them
in the device tree as "fixed-clock" nodes.

So, as per your suggestion I will add hosc and losc as clock providers
for the clock controller like below in next revision:

clocks = <&hosc>,  <&losc>;

Thanks,
Mani
> > +
> > +	clock: clock-controller@...60000 {
> > +		compatible = "actions,s900-clock";
> > +		reg = <0 0xe0160000 0 0x1000>;
> > +		#clock-cells = <1>;
> > +	};
> > +
> >  	soc {
> >  		compatible = "simple-bus";
> >  		#address-cells = <2>;
> > -- 
> > 2.7.4
> >