Problem of initialization of platform-ehci-usb in sbsa-ref

[王宇泉]

Hi,

As a junior OS engineer, I met a problem of initialization of platform-ehci-usb in sbsa-ref recently. 

The result of sbsa-acs(UEFI Shell application) on sbsa-ref shows that "Peripheral: Num of USB controllers: 0". 

And I found that the platform-ehci-usb in qemu is a 32-bits DMA device while our sbsa-ref machine does not own 

DRAM memory below 4G. It seems like a contradiction point.Connecting SMMUv3 with the platform EHCI 

in order to probe it can be a goood way ? Or there are some detail usage I ignored?​

Thanks

Yuquan Wang

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