Hello, in xHCI mode I'm experiencing random disconnects and reconnects of my ASMedia ASM1051-based external HDD enclosure. The only combination where the disconnects are happening is Intel USB Host Controller + Linux kernel + XHCI mode (see further observations below). I did some tracing with libpcap (can be opened in Wireshark). I did one trace on the NEC chipset where I have no disconnects and one on the Intel chipset where I do experience disconnects. The Intel output clearly shows that at some point in time a URB_INTERRUPT is sent from "1.1" (I suppose it is the hub) to the host (packet 1780) and the host requests a port reset (packet 1800). The procedure repeats after a random time (packet 3648). The NEC trace does not have such interrupts. Why is that interrupt sent? Where is it coming from? Additional info and observations below: Observations: - independent of activity/workload - works perfectly under Windows 7 in XHCI mode - works everywhere (Linux and Windows) when using USB 2.0 mode (EHCI) - tried with kernels 4.0.5, 4.2.0 and 3.18.16 - no difference - enabling/disabling runtime PM and USB power management doesn't make any difference - works on a different host hardware with a NEC USB3.0 host controller (see details below). Tested with kernel 3.17.7. Traces can be downloaded here: http://wikisend.com/download/136936/usb3_intel.pcapng.gz http://wikisend.com/download/612580/usb3_nec.pcapng.gz Output of /var/log/messages demonstrating the issue: http://pastebin.com/wbUr5mMe lsusb and lspci outputs (Intel hardware): http://pastebin.com/XDEz2x2g lsusb and lspci outputs (NEC hardware): http://pastebin.com/1M1ZVyJr Thanks for help, Eugen -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html