linux-kernel - Re: [PATCH 1/2] media: dt-bindings: allwinner: h6-vpu-g2: Add IOMMU reference property

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Date:   Tue, 15 Nov 2022 22:30:26 +0100
From:   Jernej Škrabec <jernej.skrabec@...il.com>
To:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Samuel Holland <samuel@...lland.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Chen-Yu Tsai <wenst@...omium.org>
Cc:     Chen-Yu Tsai <wenst@...omium.org>, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-sunxi@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] media: dt-bindings: allwinner: h6-vpu-g2: Add IOMMU reference property

Dne torek, 15. november 2022 ob 10:06:43 CET je Chen-Yu Tsai napisal(a):
> The Hantro G2 video decoder block sits behind an IOMMU. The device tree
> binding needs a property to reference it. Without a reference for the
> implementation to properly configure the IOMMU, it will fault and cause
> the video decoder to fail.

Note, Hantro G2 can happily work without IOMMU, if it is disabled for whole 
system, like disabling driver in kernel config. In such cases, it uses CMA.

Anyway, it's true that there should be proper reference in DT and bindings, 
so:
Acked-by: Jernej Skrabec <jernej.skrabec@...il.com>

Best regards,
Jernej

> 
> Add an "iommus" property for referring to the IOMMU port. The master ID
> in the example is taken from the IOMMU fault error message on Linux,
> and the number seems to match the order in the user manual's IOMMU
> diagram.
> 
> Fixes: fd6be12716c4 ("media: dt-bindings: allwinner: document H6 Hantro G2
> binding") Signed-off-by: Chen-Yu Tsai <wenst@...omium.org>
> ---
>  .../bindings/media/allwinner,sun50i-h6-vpu-g2.yaml           | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git
> a/Documentation/devicetree/bindings/media/allwinner,sun50i-h6-vpu-g2.yaml
> b/Documentation/devicetree/bindings/media/allwinner,sun50i-h6-vpu-g2.yaml
> index 24d7bf21499e..9d44236f2deb 100644
> ---
> a/Documentation/devicetree/bindings/media/allwinner,sun50i-h6-vpu-g2.yaml
> +++
> b/Documentation/devicetree/bindings/media/allwinner,sun50i-h6-vpu-g2.yaml
> @@ -36,6 +36,9 @@ properties:
>    resets:
>      maxItems: 1
> 
> +  iommus:
> +    maxItems: 1
> +
>  required:
>    - compatible
>    - reg
> @@ -43,6 +46,7 @@ required:
>    - clocks
>    - clock-names
>    - resets
> +  - iommus
> 
>  additionalProperties: false
> 
> @@ -59,6 +63,7 @@ examples:
>          clocks = <&ccu CLK_BUS_VP9>, <&ccu CLK_VP9>;
>          clock-names = "bus", "mod";
>          resets = <&ccu RST_BUS_VP9>;
> +        iommus = <&iommu 5>;
>      };
> 
>  ...