linux-kernel - Re: [PATCH v2 4/6] arm64: dts: axiado: Add initial support for AX3000 SoC and eval board

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Message-ID: <56044658-925d-473c-9859-d4f10aa9330e@axiado.com>
Date: Mon, 23 Jun 2025 05:56:14 +0000
From: Harshit Shah <hshah@...ado.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>,
	Linus Walleij <linus.walleij@...aro.org>, Bartosz Golaszewski
	<brgl@...ev.pl>, Arnd Bergmann <arnd@...db.de>, Catalin Marinas
	<catalin.marinas@....com>, Will Deacon <will@...nel.org>
CC: "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-gpio@...r.kernel.org"
	<linux-gpio@...r.kernel.org>, "soc@...ts.linux.dev" <soc@...ts.linux.dev>
Subject: Re: [PATCH v2 4/6] arm64: dts: axiado: Add initial support for AX3000
 SoC and eval board

On 6/22/2025 2:49 AM, Krzysztof Kozlowski wrote:
> CAUTION: This email originated from outside of the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe.
>
>
> On 20/06/2025 23:18, Harshit Shah wrote:
>> On 6/19/2025 11:08 PM, Krzysztof Kozlowski wrote:
>>>>>> +
>>>>>> +             spi_clk: spi_clk {
>>>>>> +                     compatible = "fixed-clock";
>>>>>> +                     #clock-cells = <0>;
>>>>>> +                     clock-frequency = <25000000>;
>>>>>> +             };
>>>>>> +
>>>>>> +             apb_pclk: apb_pclk {
>>>>> No underscores in node names, but all these look incorrect - don't you
>>>>> have clock controller?
>>>> Noted, we will remove the "_" from the nodes. We do have clock
>>>> controller however that is being accessed by other CPU before Linux will
>>>> come-up.
>>> What does it mean? Is the clock controller not available at all for
>>> Linux or any other OS?
>> Apologies for the confusion. Yes, clock controller is available however
>> it is only accessible by another CPU which boots up before Linux comes up.
>>
>> This another CPU is setting up the various output clocks (& PLLs) before
>> the Linux comes up.
>>
>> So, that's the reason haven not added the clock controller in this DTS
>> but only will add fixed clocks.
> And what happens if that other part decides to change frequencies?

Good question. The current list of the peripheral in the device tree are 
using the clock those are constant and can not be changed.

So, I am planning to add only following as a part of this patchset.

      clocks {
                clk_xin: clock-200000000 {
                        compatible = "fixed-clock";
                        #clock-cells = <0>;
                        clock-frequency = <200000000>;
                        clock-output-names = "clk_xin";
                };
                refclk: clock-125000000 {
                        compatible = "fixed-clock";
                        #clock-cells = <0>;
                        clock-frequency = <125000000>;
                };
        };

Later, we will add more patches as a part of next-separate series for 
the controller, clocks(those can change) and other peripherals.

Is this okay that I keep only above fixed clock entries for this initial 
patch-set?

>
> Best regards,
> Krzysztof

Regards,

Harshit.