linux-kernel - Re: [RFC PATCH v2 03/19] dt-bindings: power: thead,th1520: Add support for power domains

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Message-ID: <756031bf-4f81-424d-8cbc-db27ac27f6dd@samsung.com>
Date: Tue, 24 Dec 2024 10:31:44 +0100
From: Michal Wilczynski <m.wilczynski@...sung.com>
To: Krzysztof Kozlowski <krzk@...nel.org>, mturquette@...libre.com,
	sboyd@...nel.org, robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org,
	drew@...7.com, guoren@...nel.org, wefu@...hat.com, jassisinghbrar@...il.com,
	paul.walmsley@...ive.com, palmer@...belt.com, aou@...s.berkeley.edu,
	frank.binns@...tec.com, matt.coster@...tec.com,
	maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de,
	airlied@...il.com, simona@...ll.ch, ulf.hansson@...aro.org,
	jszhang@...nel.org, p.zabel@...gutronix.de, m.szyprowski@...sung.com
Cc: linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org,
	dri-devel@...ts.freedesktop.org, linux-pm@...r.kernel.org
Subject: Re: [RFC PATCH v2 03/19] dt-bindings: power: thead,th1520: Add
 support for power domains



On 12/23/24 17:09, Krzysztof Kozlowski wrote:
> On 23/12/2024 13:55, Michal Wilczynski wrote:
>> +  compatible:
>> +    const: thead,th1520-pd
>> +
>> +  "#power-domain-cells":
>> +    const: 1
>> +
>> +additionalProperties: false
>> +
>> +required:
>> +  - compatible
>> +  - "#power-domain-cells"
>> +
>> +examples:
>> +  - |
>> +    firmware {
> 
> Drop
> 
>> +        aon: aon {
>> +            compatible = "thead,th1520-aon";
>> +            mboxes = <&mbox_910t 1>;
>> +            mbox-names = "aon";
> 
> Drop aon node... but the main problem is you do not have any resources
> in your power-domain device node, assuming your binding is complete.
> This suggests that this is part of aon, not separate device. Fold the
> device node into its parent (so everything goes to AON).

Merging everything to AON node would definitely work. I was looking at
the other implementations of firmware protocols for example, and that's
how I figured the current implementation:

arch/arm/boot/dts/broadcom/bcm2835-rpi.dtsi
soc {
	firmware: firmware {
		compatible = "raspberrypi,bcm2835-firmware", "simple-mfd";
		mboxes = <&mailbox>;

		firmware_clocks: clocks {
			compatible = "raspberrypi,firmware-clocks";
			#clock-cells = <1>;
		};
	};

	power: power {
		compatible = "raspberrypi,bcm2835-power";
		firmware = <&firmware>;
		#power-domain-cells = <1>;
	};
};

This is fairly similar, as the firmware is passed as property, instead
as in a parent-child relationship. Would you consider it more canonical
?

I would be happy to merge everything to AON node, and merge the
power-domain driver and AON driver together, but it seemed to me like
those could use some separation, and since power-domain and the AON
represent actual HW it's fine to represent them in the device tree.

Thanks,
Michał
> 
>> +
>> +            pd: power-domain {
>> +                compatible = "thead,th1520-pd";
>> +                #power-domain-cells = <1>;
>> +            };
>> +        };
>> +    };
> 
> Best regards,
> Krzysztof
>