linux-kernel - Re: [PATCH v3 1/3] dt-bindings: usb: mtk-xhci: add a property for Gen1 isoc-in transfer issue

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Message-ID: <26766389b92dbc0996a7e9c461a2f27c790999fb.camel@mediatek.com>
Date: Wed, 27 Dec 2023 02:03:02 +0000
From: Chunfeng Yun (云春峰) <Chunfeng.Yun@...iatek.com>
To: "krzysztof.kozlowski@...aro.org" <krzysztof.kozlowski@...aro.org>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	"krzysztof.kozlowski+dt@...aro.org" <krzysztof.kozlowski+dt@...aro.org>,
	"angelogioacchino.delregno@...labora.com"
	<angelogioacchino.delregno@...labora.com>
CC: "linux-mediatek@...ts.infradead.org" <linux-mediatek@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"mathias.nyman@...el.com" <mathias.nyman@...el.com>,
	Eddie Hung (洪正鑫) <Eddie.Hung@...iatek.com>,
	"conor+dt@...nel.org" <conor+dt@...nel.org>,
	Macpaul Lin (林智斌) <Macpaul.Lin@...iatek.com>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "matthias.bgg@...il.com"
	<matthias.bgg@...il.com>
Subject: Re: [PATCH v3 1/3] dt-bindings: usb: mtk-xhci: add a property for
 Gen1 isoc-in transfer issue

On Wed, 2023-12-20 at 08:38 +0100, Krzysztof Kozlowski wrote:
>  	 
> External email : Please do not click links or open attachments until
> you have verified the sender or the content.
>  On 20/12/2023 03:58, 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 "rx-fifo-depth" to work around this hardware
> issue,
> > prefer to use 3k bytes;
> > The side-effect is that may cause performance drop about 10%,
> including
> > bulk transfer.
> > 
> > Signed-off-by: Chunfeng Yun <chunfeng.yun@...iatek.com>
> > ---
> > v3: add fifo depth unit, change the value range from 0-3 to 1-4
> > v2: change 'mediatek,rxfifo-depth' to 'rx-fifo-depth'
> > ---
> >  .../devicetree/bindings/usb/mediatek,mtk-xhci.yaml   | 12
> ++++++++++++
> >  1 file changed, 12 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/usb/mediatek,mtk-
> xhci.yaml b/Documentation/devicetree/bindings/usb/mediatek,mtk-
> xhci.yaml
> > index e9644e333d78..9478b7031796 100644
> > --- a/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
> > +++ b/Documentation/devicetree/bindings/usb/mediatek,mtk-xhci.yaml
> > @@ -124,6 +124,18 @@ properties:
> >        defined in the xHCI spec on MTK's controller.
> >      default: 5000
> >  
> > +  rx-fifo-depth:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description:
> > +      It is a quirk used to work around Gen1 isoc-in endpoint
> transfer issue
> > +      that still send out unexpected ACK after device finish the
> burst transfer
> > +      with a short packet and cause an exception, specially on a
> 4K camera
> > +      device, it happens on controller before about IPM v1.6.0;
> the side-effect
> > +      is that may cause performance drop about 10%, include bulk
> transfer,
> > +      prefer to use 3 here. The unit is 1K bytes.
> 
> NAK. Read comments on previous submission.
Ok, will do it today

Thanks a lot

> 
> Best regards,
> Krzysztof
>