Re: [PATCH v4 1/3] dt-bindings: usb: mtk-xhci: add a property for Gen1 isoc-in transfer issue

["Chunfeng Yun (云春峰)" <Chunfeng.Yun@mediatek.com>]

On Thu, 2023-12-28 at 12:44 +0200, Mathias Nyman wrote:
>  	 
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>  Hi
> 
> On 27.12.2023 8.03, 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.
> 
> Is it be possible to detect those Mediatek xHC versions that need
> this
> workaround in the xhci-mtk driver directly?
the version info is saved in IPPC register, when support dual-role
mode, xhci-mtk driver can't access these register which are controlled
by dual-role controller mtu3 driver;
another reason is that some cases, e.g. connected a on-board fixed mass
storage device, do not use 4K camera, it's better to use the default
rx-fifo-depth;

Thanks
> 
> This way we could avoid passing a new "rx-fifo-depth" property to it.
> 
> Thanks
> Mathias
> 
>