linux-kernel - Re: [PATCH 1/2] dt-bindings: mfd: syscon: introduce no-auto-mmio property for syscons

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Message-ID: <20251030181643.GA130921-robh@kernel.org>
Date: Thu, 30 Oct 2025 13:16:43 -0500
From: Rob Herring <robh@...nel.org>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: Lee Jones <lee@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: mfd: syscon: introduce no-auto-mmio
 property for syscons

On Wed, Oct 29, 2025 at 08:27:05PM +0300, Dan Carpenter wrote:
> Generally, syscons are created automatically and accessed direclty via
> MMIO however sometimes syscons might only be accessible from the secure
> partition or through SCMI etc.  Introduce the no-auto-mmio property to
> tell the operating system that the syscon needs to be handled manually.
> 
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> ---
>  Documentation/devicetree/bindings/mfd/syscon.yaml | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/mfd/syscon.yaml b/Documentation/devicetree/bindings/mfd/syscon.yaml
> index 657c38175fba..a0ad12ae0bee 100644
> --- a/Documentation/devicetree/bindings/mfd/syscon.yaml
> +++ b/Documentation/devicetree/bindings/mfd/syscon.yaml
> @@ -245,6 +245,10 @@ properties:
>    resets:
>      maxItems: 1
>  
> +  no-auto-mmio:
> +    type: boolean
> +    description: Prevents the syscon from being created automatically

"syscon" literally means "have Linux create a regmap for me". If you 
don't want that, don't use the "syscon" compatible. Really, I wish we'd 
never added it in the first place.

Rob