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From: Krzysztof Kozlowski <krzk@kernel.org>
To: Bibek Kumar Patro <bibek.patro@oss.qualcomm.com>
Cc: Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	 Joerg Roedel <joro@8bytes.org>, Rob Herring <robh@kernel.org>,
	 Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>,
	 linux-arm-kernel@lists.infradead.org, iommu@lists.linux.dev,
	devicetree@vger.kernel.org,  linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] dt-bindings: iommu: arm,smmu: Document optional interconnects property
Date: Mon, 18 May 2026 14:33:30 +0200	[thread overview]
Message-ID: <20260518-mellow-robust-caterpillar-93fcaa@quoll> (raw)
In-Reply-To: <20260516-smmu_interconnect_addition-v1-1-f889d933f5c1@oss.qualcomm.com>

On Sat, May 16, 2026 at 06:04:03PM +0530, Bibek Kumar Patro wrote:
> Some SoC implementations require a bandwidth vote on an interconnect

Then this should be disallowed for other devices in "allOf:".

> path before the SMMU register space is accessible. Add the optional
> 'interconnects' property to the binding to allow platform DT nodes
> to describe this path.
> 
> The arm-smmu driver uses these properties to vote for bandwidth before
> accessing any SMMU registers and releases the vote on runtime suspend.
> 
> Signed-off-by: Bibek Kumar Patro <bibek.patro@oss.qualcomm.com>
> ---
>  Documentation/devicetree/bindings/iommu/arm,smmu.yaml | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> index 06fb5c8e7547cb7a92823adc2772b94f747376a6..5cbf944f2d3e178b3723d4dbaa19ee0d33446979 100644
> --- a/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> +++ b/Documentation/devicetree/bindings/iommu/arm,smmu.yaml
> @@ -243,6 +243,15 @@ properties:
>      minItems: 1
>      maxItems: 3
>  
> +  interconnects:
> +    maxItems: 1
> +    description:
> +      Optional interconnect path to the SMMU register space. On some SoCs
> +      the SMMU registers are only accessible after a bandwidth vote has been

Drivers are irrelevant here, drop. Also first sentence is redundant.
Schema says what is and what is not optional.

Best regards,
Krzysztof


  reply	other threads:[~2026-05-18 12:33 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-05-16 12:34 [PATCH 0/2] iommu/arm-smmu: Add interconnect bandwidth voting support Bibek Kumar Patro
2026-05-16 12:34 ` [PATCH 1/2] dt-bindings: iommu: arm,smmu: Document optional interconnects property Bibek Kumar Patro
2026-05-18 12:33   ` Krzysztof Kozlowski [this message]
2026-05-19 13:53     ` Bibek Kumar Patro
2026-05-16 12:34 ` [PATCH 2/2] iommu/arm-smmu: Add interconnect bandwidth voting support Bibek Kumar Patro
2026-05-16 13:02   ` sashiko-bot
2026-05-23 14:41     ` Bibek Kumar Patro
2026-05-26 12:08       ` Bibek Kumar Patro

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