Re: [PATCH v2 1/8] dt-bindings: mfd: khadas: Add new compatible for Khadas VIM4 MCU

From: Neil Armstrong <neil.armstrong@linaro.org>
To: Ronald Claveau <linux-kernel-dev@aliel.fr>,
	Rob Herring <robh@kernel.org>
Cc: Lee Jones <lee@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	Andi Shyti <andi.shyti@kernel.org>,
	Kevin Hilman <khilman@baylibre.com>,
	Jerome Brunet <jbrunet@baylibre.com>,
	Martin Blumenstingl <martin.blumenstingl@googlemail.com>,
	Beniamino Galvani <b.galvani@gmail.com>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	Daniel Lezcano <daniel.lezcano@kernel.org>,
	Zhang Rui <rui.zhang@intel.com>,
	Lukasz Luba <lukasz.luba@arm.com>,
	Liam Girdwood <lgirdwood@gmail.com>,
	Mark Brown <broonie@kernel.org>,
	linux-amlogic@lists.infradead.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH v2 1/8] dt-bindings: mfd: khadas: Add new compatible for Khadas VIM4 MCU
Date: Fri, 17 Apr 2026 09:53:11 +0200	[thread overview]
Message-ID: <6758aaa2-ac1a-4751-aece-2b445b84f2bc@linaro.org> (raw)
In-Reply-To: <6fc8ddeb-d54d-473d-94d2-49dc78a07154@aliel.fr>

On 4/16/26 10:25, Ronald Claveau wrote:
> On 4/15/26 11:48 PM, Rob Herring wrote:
>> On Fri, Apr 03, 2026 at 06:08:34PM +0200, Ronald Claveau wrote:
>>> The Khadas VIM4 MCU register is slightly different
>>> from previous boards' MCU.
>>> This board also features a switchable power source for its fan.
>>>
>>> Signed-off-by: Ronald Claveau <linux-kernel-dev@aliel.fr>
>>> ---
>>>   Documentation/devicetree/bindings/mfd/khadas,mcu.yaml | 5 +++++
>>>   1 file changed, 5 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/mfd/khadas,mcu.yaml b/Documentation/devicetree/bindings/mfd/khadas,mcu.yaml
>>> index 084960fd5a1fd..67769ef5d58b1 100644
>>> --- a/Documentation/devicetree/bindings/mfd/khadas,mcu.yaml
>>> +++ b/Documentation/devicetree/bindings/mfd/khadas,mcu.yaml
>>> @@ -18,6 +18,7 @@ properties:
>>>     compatible:
>>>       enum:
>>>         - khadas,mcu # MCU revision is discoverable
>>
>> The revision is no longer discoverable as was claimed?
>>
> 
> The firmware revision is still discoverable, and via the same register,
> but the VIM4 MCU has a different register layout (eg: no DEVICE_NO
> register). The new compatible is needed to describe a different MCU
> variant, not a different revision of the same MCU.
> I will remove the comment as it is confusing with new boards.

Yes basically it was discoverable for earlier MCU version, but is not
for this particular board version.

Keep the comment, but add a comment on the vim4 entry saying this variant
is not discoverable.

Neil

> 
>>> +      - khadas,vim4-mcu
>>>   
>>>     "#cooling-cells": # Only needed for boards having FAN control feature
>>>       const: 2
>>> @@ -25,6 +26,10 @@ properties:
>>>     reg:
>>>       maxItems: 1
>>>   
>>> +  fan-supply:
>>> +    description: Phandle to the regulator that powers the fan.
>>> +    $ref: /schemas/types.yaml#/definitions/phandle
>>> +
>>>   required:
>>>     - compatible
>>>     - reg
>>>
>>> -- 
>>> 2.49.0
>>>
> 
> 

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