linux-kernel - Re: [PATCH 06/14] dt-bindings: clock: milbeaut: add Milbeaut clock description

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Message-ID: <15178a7c-7d12-7c10-6093-192754827b5a@socionext.com>
Date:   Mon, 3 Dec 2018 17:08:15 +0900
From:   "Sugaya, Taichi" <sugaya.taichi@...ionext.com>
To:     Stephen Boyd <sboyd@...nel.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org
Cc:     Michael Turquette <mturquette@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Russell King <linux@...linux.org.uk>,
        Jiri Slaby <jslaby@...e.com>,
        Masami Hiramatsu <masami.hiramatsu@...aro.org>,
        Jassi Brar <jaswinder.singh@...aro.org>
Subject: Re: [PATCH 06/14] dt-bindings: clock: milbeaut: add Milbeaut clock
 description

Hi,

Thank you for your comments.

On 2018/11/30 17:19, Stephen Boyd wrote:
> Quoting Sugaya Taichi (2018-11-18 17:01:11)
>> Add DT bindings document for Milbeaut clock.
>>
>> Signed-off-by: Sugaya Taichi <sugaya.taichi@...ionext.com>
>> ---
>>   .../devicetree/bindings/clock/milbeaut-clock.txt   | 93 ++++++++++++++++++++++
>>   1 file changed, 93 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/clock/milbeaut-clock.txt
>>
>> diff --git a/Documentation/devicetree/bindings/clock/milbeaut-clock.txt b/Documentation/devicetree/bindings/clock/milbeaut-clock.txt
>> new file mode 100644
>> index 0000000..5c093c8
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/clock/milbeaut-clock.txt
>> @@ -0,0 +1,93 @@
>> +Milbeaut M10V Clock Controller Binding
>> +----------------------------------------
>> +Milbeaut clock controller is consists of few oscillators, PLL, multiplexer
>> +and few divider modules
>> +
>> +This binding uses common clock bindings
>> +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
>> +
>> +Required properties:
>> +- compatible: shall be "socionext,milbeaut-m10v-clk-regs"
>> +- reg: shall contain base address and length of clock registers
>> +- #clock-cells: shall be 0
>> +
>> +Example:
>> +       m10v-clk-tree@ {
>> +               compatible = "socionext,milbeaut-m10v-clk-regs";
>> +               reg = <0x1d021000 0x4000>;
>> +
>> +               clocks {
>> +                       #address-cells = <0>;
>> +                       #size-cells = <0>;
>> +
>> +                       uclk40xi: uclk40xi {
>> +                               compatible = "fixed-clock";
>> +                               #clock-cells = <0>;
>> +                               clock-frequency = <40000000>;
>> +                       };
>> +               };
> 
> This style of binding is highly discouraged. We don't describe each and
> every clk in DT, we describe clk controllers and their outputs and
> inputs in DT. The driver is the place where the clock controller
> describes the internal clk topology of that controller. Also, fixed
> frequency clks are typically oscillators and those would come from the
> board dts file, but otherwise I wouldn't expect to see fixed frequency
> clks in DT.

I understand. Received the similar comment from Rob in the DT part also.

> 
>> +       }
>> +
>> +The clock consumer shall specify the desired clock-output of the clock
>> +controller (as defined in [2]) by specifying output-id in its "clock"
>> +phandle cell
>> +[2] arch/arm/boot/dts/milbeaut-m10v-clk.h
>> +
> [...]
>> +
>> +Example
>> +       piclk_mux_0: spiclk_mux_0 {
>> +               compatible = "socionext,m10v-clk-div";
>> +               #clock-cells = <0>;
>> +               clocks = <&pll10_div_1_2>;
>> +               offset = <bSPICLK>;
>> +               mask = <0x3>;
>> +               ratios = <4 0x5 2 0x4>;
>> +       };
>> +
>> +       pll10: pll10 {
>> +               compatible = "socionext,m10v-pll-fixed-factor";
>> +               #clock-cells = <0>;
>> +               clocks = <&uclk40xi>;
>> +               offset = <10>;
>> +               clock-div = <5>;
>> +               clock-mult = <108>;
>> +       };
>> +
>> +       emmcclk: emmcclk {
>> +               compatible = "socionext,m10v-clk-div";
>> +               #clock-cells = <0>;
>> +               clocks = <&pll11>;
>> +               offset = <bEMMCCLK>;
>> +               mask = <0x3>;
>> +               ratios = <15 0x7 10 0x6 9 0x5 8 0x4>;
> 
> Yeah, please no. This whole binding needs a rewrite to not have one node
> per clk.

OK, I will renew the binding.

Thanks.
Sugaya Taichi

>