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Date:   Fri, 6 Aug 2021 14:43:20 -0600
From:   Rob Herring <robh@kernel.org>
To:     Chunfeng Yun <chunfeng.yun@mediatek.com>
Cc:     Mathias Nyman <mathias.nyman@intel.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        linux-usb@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, Eddie Hung <eddie.hung@mediatek.com>
Subject: Re: [PATCH 03/11] dt-bindings: usb: mtk-xhci: add compatible for
 mt8195
Message-ID: <YQ2e6AGFi7beqp6Q@robh.at.kernel.org>
References: <1627635002-24521-1-git-send-email-chunfeng.yun@mediatek.com>
 <1627635002-24521-3-git-send-email-chunfeng.yun@mediatek.com>
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On Fri, Jul 30, 2021 at 04:49:54PM +0800, Chunfeng Yun wrote:
> There are 4 USB controllers on MT8195, the controllers (IP1~IP3,
> exclude IP0) have a wrong default SOF/ITP interval which is
> calculated from the frame counter clock 24Mhz by default, but
> in fact, the frame counter clock is 48Mhz, so we should set
> the accurate interval according to 48Mhz. Here add a new compatible
> for MT8195, it's also supported in driver. But the first controller
> (IP0) has no such issue, we prefer to use generic compatible,
> e.g. mt8192's compatible.

That only works until you find some 8195 bug common to all instances. 
Can't you read the clock frequency?

> 
> Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> ---
>  Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml b/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
> index 61a0e550b5d6..753e043e5327 100644
> --- a/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
> +++ b/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
> @@ -31,6 +31,7 @@ properties:
>            - mediatek,mt8173-xhci
>            - mediatek,mt8183-xhci
>            - mediatek,mt8192-xhci
> +          - mediatek,mt8195-xhci
>        - const: mediatek,mtk-xhci
>  
>    reg:
> -- 
> 2.18.0
> 
>