linux-kernel - Re: [PATCH v2 2/5] dt-bindings: iommu: mediatek: Fix interrupt count constraint for new SoCs

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Message-ID: <8883c84d-8333-4b04-83b5-022be5b6153c@collabora.com>
Date: Mon, 30 Sep 2024 10:49:06 +0200
From: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
To: Macpaul Lin <macpaul.lin@...iatek.com>,
 Chun-Kuang Hu <chunkuang.hu@...nel.org>,
 Philipp Zabel <p.zabel@...gutronix.de>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>,
 Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>, Yong Wu <yong.wu@...iatek.com>,
 Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
 Robin Murphy <robin.murphy@....com>,
 Matthias Brugger <matthias.bgg@...il.com>, CK Hu <ck.hu@...iatek.com>,
 Jitao shi <jitao.shi@...iatek.com>, Tinghan Shen
 <tinghan.shen@...iatek.com>, Seiya Wang <seiya.wang@...iatek.com>,
 Ben Lok <ben.lok@...iatek.com>, "Nancy . Lin" <nancy.lin@...iatek.com>,
 dri-devel@...ts.freedesktop.org, linux-mediatek@...ts.infradead.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 iommu@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
 Alexandre Mergnat <amergnat@...libre.com>
Cc: Bear Wang <bear.wang@...iatek.com>, Pablo Sun <pablo.sun@...iatek.com>,
 Macpaul Lin <macpaul@...il.com>, Sen Chu <sen.chu@...iatek.com>,
 Chris-qj chen <chris-qj.chen@...iatek.com>,
 MediaTek Chromebook Upstream
 <Project_Global_Chrome_Upstream_Group@...iatek.com>,
 Chen-Yu Tsai <wenst@...omium.org>
Subject: Re: [PATCH v2 2/5] dt-bindings: iommu: mediatek: Fix interrupt count
 constraint for new SoCs

Il 26/09/24 13:14, Macpaul Lin ha scritto:
> The infra-iommu node in mt8195.dtsi was triggering a CHECK_DTBS error due
> to an excessively long 'interrupts' property. The error message was:
> 
>    infra-iommu@...15000: interrupts: [[0, 795, 4, 0], [0, 796, 4, 0],
>                       [0, 797, 4, 0], [0, 798, 4, 0], [0, 799, 4, 0]]
>                       is too long
> 
> To address this issue, add "minItems: 1" and "maxItems: 5" constraints to
> the 'interrupts' property in the DT binding schema. This change allows for
> flexibility in the number of interrupts for new SoCs.
> The purpose of these 5 interrupts is also added.
> 
> Fixes: bca28426805d ("dt-bindings: iommu: mediatek: Convert IOMMU to DT schema")
> Signed-off-by: Macpaul Lin <macpaul.lin@...iatek.com>
> ---
>   .../bindings/iommu/mediatek,iommu.yaml        | 25 ++++++++++++++++++-
>   1 file changed, 24 insertions(+), 1 deletion(-)
> 
> Changes for v2:
>   - commit message: re-formatting and add a description of adding 5 interrupts.
>   - add 'description' and 'maxItems: 5' for 'interrupt' property of
>     'mt8195-iommu-infra'
>   - others keeps 'maxItems: 1'
> 
> diff --git a/Documentation/devicetree/bindings/iommu/mediatek,iommu.yaml b/Documentation/devicetree/bindings/iommu/mediatek,iommu.yaml
> index ea6b0f5f24de..fdd2996d2a31 100644
> --- a/Documentation/devicetree/bindings/iommu/mediatek,iommu.yaml
> +++ b/Documentation/devicetree/bindings/iommu/mediatek,iommu.yaml
> @@ -96,7 +96,8 @@ properties:
>       maxItems: 1
>   
>     interrupts:
> -    maxItems: 1
> +    minItems: 1
> +    maxItems: 5
>   
>     clocks:
>       items:
> @@ -210,6 +211,28 @@ allOf:
>         required:
>           - mediatek,larbs
>   
> +  - if:
> +      properties:
> +        compatible:
> +          contains:
> +            enum:
> +              - mediatek,mt8195-iommu-infra
> +
> +    then:
> +      properties:
> +        interrupts:
> +          description: |

Do you really need to keep the formatting?

If you rephrase that as:

The infra IOMMU in MT8195 has five banks: each features one set
of APB registers for the normal world (set 0), one for the protected
world (sets 1-3) and one for the secure world (set 4), and each set
has its own interrupt. Therefore, five interrupts are needed.

...you won't need the bar :-)

> +            The IOMMU of MT8195 has 5 banks: 0/1/2/3/4.
> +            Each bank has a set of APB registers corresponding to the
> +            normal world, protected world 1/2/3, and secure world, respectively.
> +            Therefore, 5 interrupt numbers are needed.
> +          maxItems: 5

minItems: 5

Cheers,
Angelo