linux-kernel - Re: [PATCH 5/5] riscv: dts: add clock generator for Sophgo SG2042 SoC

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Date:   Wed, 15 Nov 2023 09:34:06 +0800
From:   Chen Wang <unicorn_wang@...look.com>
To:     Conor Dooley <conor@...nel.org>, Chen Wang <unicornxw@...il.com>
Cc:     aou@...s.berkeley.edu, chao.wei@...hgo.com,
        krzysztof.kozlowski+dt@...aro.org, mturquette@...libre.com,
        palmer@...belt.com, paul.walmsley@...ive.com,
        richardcochran@...il.com, robh+dt@...nel.org, sboyd@...nel.org,
        devicetree@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
        haijiao.liu@...hgo.com, xiaoguang.xing@...hgo.com
Subject: Re: [PATCH 5/5] riscv: dts: add clock generator for Sophgo SG2042 SoC


On 2023/11/15 1:31, Conor Dooley wrote:
> On Mon, Nov 13, 2023 at 09:20:11PM +0800, Chen Wang wrote:
>> From: Chen Wang <unicorn_wang@...look.com>
>>
>> Add clock generator node to device tree for SG2042, and enable clock for
>> uart0.
>>
>> Signed-off-by: Chen Wang <unicorn_wang@...look.com>
>> ---
>>   arch/riscv/boot/dts/sophgo/sg2042-clock.dtsi | 76 ++++++++++++++++++++
> There's no need to create an entirely new file for this.
Agree, I will merge this into sg2042.dtsi in next revision.
>
>>   arch/riscv/boot/dts/sophgo/sg2042.dtsi       | 10 +++
>>   2 files changed, 86 insertions(+)
>>   create mode 100644 arch/riscv/boot/dts/sophgo/sg2042-clock.dtsi
>>
>> diff --git a/arch/riscv/boot/dts/sophgo/sg2042-clock.dtsi b/arch/riscv/boot/dts/sophgo/sg2042-clock.dtsi
>> new file mode 100644
>> index 000000000000..66d2723fab35
>> --- /dev/null
>> +++ b/arch/riscv/boot/dts/sophgo/sg2042-clock.dtsi
>> @@ -0,0 +1,76 @@
>> +// SPDX-License-Identifier: (GPL-2.0 OR MIT)
>> +/*
>> + * Copyright (C) 2023 Sophgo Technology Inc. All rights reserved.
>> + */
>> +
>> +/ {
>> +	cgi: oscillator {
>> +		compatible = "fixed-clock";
>> +		clock-frequency = <25000000>;
>> +		clock-output-names = "cgi";
>> +		#clock-cells = <0>;
>> +	};
> What actually is this oscillator?
> Is it provided by another clock controller on the SoC, or is it provided
> by an oscillator on the board?

This oscillator is an individual ic chip outside the SoC on the board, 
that's why I list it outside soc node.

Actually the "cgi" is abbrevation for "Clock Generation IC chip".

>> +
>> +	clkgen: clock-controller {
>> +		compatible = "sophgo,sg2042-clkgen";
>> +		#clock-cells = <1>;
>> +		system-ctrl = <&sys_ctrl>;
> Why is this node not a child of the system controller?

I will move this node to child of syscon in next revision, thanks for 
your reminder.


>
> Cheers,
> Conor.