59cf445754
Commit 85d07c556216 ("USB: core: Unite old scheme and new scheme descriptor reads") altered the way USB devices are enumerated following detection, and in the process it messed up the initialization of SuperSpeed (or faster) devices: [ 31.650759] usb 2-1: new SuperSpeed Plus Gen 2x1 USB device number 2 using xhci_hcd [ 31.663107] usb 2-1: device descriptor read/8, error -71 [ 31.952697] usb 2-1: new SuperSpeed Plus Gen 2x1 USB device number 3 using xhci_hcd [ 31.965122] usb 2-1: device descriptor read/8, error -71 [ 32.080991] usb usb2-port1: attempt power cycle ... The problem was caused by the commit forgetting that in SuperSpeed or faster devices, the device descriptor uses a logarithmic encoding of the bMaxPacketSize0 value. (For some reason I thought the 255 case in the switch statement was meant for these devices, but it isn't -- it was meant for Wireless USB and is no longer needed.) We can fix the oversight by testing for buf->bMaxPacketSize0 = 9 (meaning 512, the actual maxpacket size for ep0 on all SuperSpeed devices) and straightening out the logic that checks and adjusts our initial guesses of the maxpacket value. Reported-and-tested-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com> Closes: https://lore.kernel.org/linux-usb/20230810002257.nadxmfmrobkaxgnz@synopsys.com/ Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Fixes: 85d07c556216 ("USB: core: Unite old scheme and new scheme descriptor reads") Link: https://lore.kernel.org/r/8809e6c5-59d5-4d2d-ac8f-6d106658ad73@rowland.harvard.edu Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>