Hi Libo, I review the USB Spec 2.0 and have some confusion when check the spec as below: From the USB 2.0 spec: Section 5.5.3 Control Transfer Packet Size Constraints ... In order to determine the maximum packet size for the Default Control Pipe, the USB System Software reads the device descriptor. The host will read the first eight bytes of the device descriptor. The device always responds with at least these initial bytes in a single packet. After the host reads the initial part of the device descriptor, it is guaranteed to have read this default pipe’s wMaxPacketSize field (byte 7 of the device descriptor). It will then allow the correct size for all subsequent transactions. For all other control endpoints, the maximum data payload size is known after configuration so that the USB System Software can ensure that no data payload will be sent to the endpoint that is larger than the supported size. ... Also, Section 9.1.2 Bus Enumeration ... 3. Now that the host knows the port to which the new device has been attached, the host then waits for at least 100 ms to allow completion of an insertion process and for power at the device to become stable. The host then issues a port enable and reset command to that port. Refer to Section 7.1.7.5 for sequence of events and timings of connection through device reset. 4. The hub performs the required reset processing for that port (see Section 11.5.1.5). When the reset signal is released, the port has been enabled. The USB device is now in the Default state and can draw no more than 100 mA from VBUS. All of its registers and state have been reset and it answers to the default address. 5. The host assigns a unique address to the USB device, moving the device to the Address state. 6. Before the USB device receives a unique address, its Default Control Pipe is still accessible via the default address. The host reads the device descriptor to determine what actual maximum data payload size this USB device’s default pipe can use. 7. The host reads the configuration information from the device by reading each configuration zero to n-1, where n is the number of configurations. This process may take several milliseconds to complete. ... It seem that the original behavior follow the spec, but I don’t know why the device will not response and must reset it. I notice that you obtain the patch from https://techcommunity.microsoft.com/t5/microsoft-usb-blog/how-does-usb-stack-enumerate-a-device/ba-p/270685#:~:text=%20How%20does%20USB%20stack%20enumerate%20a%20device%3F,a%20request%20for%20the%20USB%20Device...%20More%20. Do you know the device behavior from the device side when the issue happened? Thanks. Guomin From: devel@edk2.groups.io On Behalf Of Guomin Jiang Sent: Tuesday, August 11, 2020 7:17 PM To: devel@edk2.groups.io; lbfeng@zd-tech.com.cn Cc: jeremy.linton@arm.com; Wu, Hao A ; Ni, Ray Subject: Re: [edk2-devel] [PATCH] MdeModulePkg/UsbBusDxe: some USB PenDisk fails enumeration. +Hao, Ray, Hi Libo, thanks for your explanation. So I think the patch is improvement for current logic. Hi Hao and Ray, Can you give some comments for the change. Hi Jeremy, It may be helpful for the ASSERT issue https://edk2.groups.io/g/devel/message/62651,can you try it? Best Regards Guomin From: devel@edk2.groups.io > On Behalf Of Feng Libo Sent: Tuesday, August 11, 2020 5:50 PM To: Jiang, Guomin > Cc: devel@edk2.groups.io; jeremy.linton@arm.com Subject: Re: [edk2-devel] [PATCH] MdeModulePkg/UsbBusDxe: some USB PenDisk fails enumeration. Hello, Mr. Jiang, Thank for the review. The original enumeration steps in the function of UsbEnumerateNewDev of file UsbEnumer.c: 1 reset the port, 2 set the usb device address, 3 get the Max Packet Size, 4 get the full device descriptor. However, when plugging a USB PenDisk with Innostor USB controller chip (VID=0x1F75, PID=0x917, USB3.1), the fourth step always fails, trace as below: ======== XhcCheckUrbResult: TRANSACTION_ERROR! Completecode = 4 XhcControlTransfer: error - Device Error, transfer - 40 UsbGetOneConfig: failed to get full descript Device Error UsbBuildDescTable: failed to get configure (index 0) UsbEnumerateNewDev: failed to build descriptor table - Device Error ======= The host controller need to get the full device descriptor, but this moment, the Pendisk device doesn't response any more. Then timeout. and UsbEnumerateNewDev complains : failed to build descriptor. We have three Pendisks from different manufacturers, all with Innostor USB controller chip. they all can't be enumerated all. And we observed the problem on both Huawei KunPeng(华为鲲鹏）and Loognson（龙芯）platforms. The three Pendisks always fail the USB enumeration. Other USB 2.0 and USB 3.0 on hand can work well. With the patch, the three pendisks and other pendisks can all work well. THanks -- Best Regards Feng Libo ZD Technology (Beijing) Co., Ltd 发件人："Jiang, Guomin" > 发送日期：2020-08-11 08:21:10 收件人："devel@edk2.groups.io" >,"Jiang, Guomin" >,"lbfeng@zd-tech.com.cn" > 抄送人："jeremy.linton@arm.com" > 主题：RE: [edk2-devel] [PATCH] MdeModulePkg/UsbBusDxe: some USB PenDisk fails enumeration. +Jeremy, I review the patch and think it is reasonable, but I want to know some more detail information 1. Can you provide the detail debug log about USB? 2. The symptom always can be seen or have fail rate? Best Regards Guomin From: devel@edk2.groups.io > On Behalf Of Guomin Jiang Sent: Thursday, August 6, 2020 12:29 PM To: devel@edk2.groups.io; lbfeng@zd-tech.com.cn Subject: Re: [edk2-devel] [PATCH] MdeModulePkg/UsbBusDxe: some USB PenDisk fails enumeration. I will review it by next weekend(8/14). Thanks. From: devel@edk2.groups.io > On Behalf Of Feng Libo Sent: Thursday, August 6, 2020 9:25 AM To: Feng Libo >; devel@edk2.groups.io Subject: Re: [edk2-devel] [PATCH] MdeModulePkg/UsbBusDxe: some USB PenDisk fails enumeration. Hello, could anyone review this PATCH? We encountered the USB enumeration problem and the patch is based on the Microsoft post as below. https://techcommunity.microsoft.com/t5/microsoft-usb-blog/how-does-usb-stack-enumerate-a-device/ba-p/270685#:~:text=%20How%20does%20USB%20stack%20enumerate%20a%20device%3F,a%20request%20for%20the%20USB%20Device...%20More%20 Thanks Best Regards Feng Libo