linux-kernel - Re: [PATCH 3/3] Documentation: add Actions S900 clock bindings

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Message-ID: <20171104094129.GB18680@linaro.org>
Date:   Sat, 4 Nov 2017 15:11:29 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Andreas Färber <afaerber@...e.de>
Cc:     mturquette@...libre.com, sboyd@...eaurora.org, robh+dt@...nel.org,
        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 3/3] Documentation: add Actions S900 clock bindings

Hi Andreas,
On Sat, Nov 04, 2017 at 04:55:04PM +0800, Andreas Färber wrote:
> Am 01.11.2017 um 03:54 schrieb Manivannan Sadhasivam:
> > This patch adds clock bindings for Actions Semi S900 SoC.
> 
> "This patch"
>
Ack. 
> > 
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > ---
> >  .../bindings/clock/actions,s900-clock.txt          | 47 ++++++++++++++++++++++
> >  1 file changed, 47 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/clock/actions,s900-clock.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/clock/actions,s900-clock.txt b/Documentation/devicetree/bindings/clock/actions,s900-clock.txt
> > new file mode 100644
> > index 0000000..951d6ad
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/clock/actions,s900-clock.txt
> > @@ -0,0 +1,47 @@
> > +* Actions s900 Clock Controller
> 
> Please consistently spell it S900 here and below - it looks especially
> odd when you upper-case all other words.
> 
Ack.
> > +
> > +The Actions s900 clock controller generates and supplies clock to various
> > +controllers within the SoC. The clock binding described here is applicable to
> > +s900 SoC.
> > +
> > +Required Properties:
> > +
> > +- compatible: should be "actions,s900-clock"
> 
> What about "actions,s900-cmu" as in Clock Management Unit? (manual
> version 1.0 section 1.5, page 6)
> 
"cmu" makes sense, will change it.
> > +- reg: physical base address of the controller and length of memory mapped
> > +  region.
> > +- #clock-cells: should be 1.
> > +
> > +Each clock is assigned an identifier and client nodes can use this identifier
> 
> ", and"?
> 
Ack.
> > +to specify the clock which they consume.
> > +
> > +All available clocks are defined as preprocessor macros in
> > +dt-bindings/clock/actions,s900-clock.h header and can be used in device
> > +tree sources.
> 
> As Rob pointed out, missing here.
> 
Will add this header to dt-bindings patch in next revision.
> > +
> > +External clocks:
> > +
> > +The hosc clock used as input for the plls is generated outside the SoC. It is
> > +expected that it is defined using standard clock bindings as "hosc".
> > +
> > +Actions s900 Clock Controller also require two more clocks:
> > + - "losc" - internal low frequency oscillator
> > + - "diff_24M" - internal differential 24MHz clock
> > +
> > +Example: Clock controller node:
> > +
> > +        clock: clock-controller@...60000 {
> > +		compatible = "actions,s900-clock";
> > +		reg = <0 0xe0160000 0 0x1000>;
> > +		#clock-cells = <1>;
> > +	};
> 
> Spaces vs. tab indentation.
> 
Ack.
> Regarding the question in the dts patch, I think cmu would be a better
> label here and there.
> 
Yeah. Will use cmu.
> > +
> > +Example: UART controller node that consumes clock generated by the clock
> > +controller:
> > +
> > +	serial5: uart@...2a000 {
> > +		compatible = "actions,s900-uart", "actions,owl-uart";
> > +		reg = <0x0 0xe012a000 0x0 0x2000>;
> > +		interrupts = <GIC_SPI 34 IRQ_TYPE_LEVEL_HIGH>;
> > +		clocks = <&clock CLK_UART5>;
> > +		clock-names = "uart";
> 
> Better not use a clock name here that is not defined in the uart binding.
> 
Agree.

Thanks,
Mani
> > +	};
> 
> Regards,
> Andreas
> 
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