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

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Date:   Sat, 4 Nov 2017 16:55:04 +0800
From:   Andreas Färber <afaerber@...e.de>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
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

Am 01.11.2017 um 03:54 schrieb Manivannan Sadhasivam:
> This patch adds clock bindings for Actions Semi S900 SoC.

"This patch"

> 
> 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.

> +
> +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)

> +- 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"?

> +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.

> +
> +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.

Regarding the question in the dts patch, I think cmu would be a better
label here and there.

> +
> +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.

> +	};

Regards,
Andreas

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