Hi,

I am using u-boot revision d141e218f3195e305c1521a0d67c81b7cb504b71 (dec 28 2015). The platform is socfpga cyclone-V.

I connected some different USB devices to my USB port, and some of them have problems. Especially, if i connect another linux box with CDC mass storage or ethernet emulation, the device is not detected.

I found that the problem is the NAK message handling: if i connect a pendrive then no NAK messages returned, but using CDC mass storage device, there are a lot of them. The problem is that the NAK messages are not handled at all: if such one received, the driver enters an endless loop (in file dwc2_otg-hcd.c: see the /* TODO: no endless loop */ comment).

AFAIK, the NAK handling is basically necessary for USB communication: i do not understand how can it work without NAK handling at all. Am i the only one having NAK messages in this case?

I need some help to resolve the NAK handling here.

Thanx in advance Gyorgy Kovesdi