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Message-ID: <c1bc144d-07d6-422c-8294-42be47f83e59@linaro.org>
Date:   Wed, 13 Dec 2023 09:05:54 +0100
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Subject: Re: [PATCH 1/3] dt-bindings: usb: mtk-xhci: add a property for Gen1
 isoc-in transfer issue
Content-Language: en-US
To:     Chunfeng Yun <chunfeng.yun@mediatek.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Rob Herring <robh+dt@kernel.org>
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Mathias Nyman <mathias.nyman@intel.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,
        Macpaul Lin <macpaul.lin@mediatek.com>,
        Eddie Hung <eddie.hung@mediatek.com>
References: <20231213063543.12435-1-chunfeng.yun@mediatek.com>
From:   Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
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In-Reply-To: <20231213063543.12435-1-chunfeng.yun@mediatek.com>
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Precedence: bulk

On 13/12/2023 07:35, Chunfeng Yun wrote:
> For Gen1 isoc-in endpoint on controller before about SSUSB IPM v1.6.0, it
> still send out unexpected ACK after receiving a short packet in burst
> transfer, this will cause an exception on connected device, specially for
> a 4k camera.
> Add a quirk property "mediatek,rxfifo-depth" to work around this hardware
> issue;
> The side-effect is that may cause performance drop about 10%, including
> bulk transfer.
> 
> Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
> ---
>  .../devicetree/bindings/usb/mediatek,mtk-xhci.yaml     | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml b/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
> index e9644e333d78..b8ed68574ba4 100644
> --- a/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
> +++ b/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
> @@ -124,6 +124,16 @@ properties:
>        defined in the xHCI spec on MTK's controller.
>      default: 5000
>  
> +  mediatek,rxfifo-depth:
> +    description:

The property description and driver patch suggest you configure the
depth of FIFO, so this should be not bool, but some uint32. And then,
use generic "fifo-depth" property to set desired depth.


Best regards,
Krzysztof