Sarah: This report surfaced in Bugzilla #59011 (see especially comments #38 and #39). Toralf reports, among other things, that the integrated "rate-matching" hub in his ThinkPad T420 (6 Series/C200 Series chipset) isn't behaving the way it should. The particular symptom is that when the hub is suspended, it does not relay wakeup requests from a downstream port to its upstream port, if the downstream device is connected at low speed and the downstream port's suspend feature isn't set. This happens with the 3.10-rc kernels, because commit 0aa2832dd0d9 changed system suspend to do a USB "global" bus suspend. None of the ports on non-SuperSpeed hubs are explicitly put into suspend mode; instead, everything on the bus goes into suspend when the root hub stops sending packets. The problem is easy to test on any system running a 3.10-rc kernel. Simply plug a low-speed USB keyboard (almost all keyboards are low speed) into a USB-2 port, suspend the system, and then see if typing on the keyboard will wake up the computer. I have tested a couple of external USB-2 hubs; one of them behaved correctly and one didn't. Regardless, it was surprising to see Toralf's report that an Intel hub doesn't work right. I don't have any machines with a comparable chipset, so I can't test one of those integrated hubs directly. Can somebody at Intel look into this? Alan Stern -- 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
