On Mon, 9 Jun 2014, Toralf Förster wrote: > On 06/19/2013 09:03 PM, Alan Stern wrote: > > 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 > > > > > Just tried kernel 3.15. - issue does still exists > https://bugzilla.kernel.org/show_bug.cgi?id=59011 Not surprising, since it is a bug in the hardware. 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
