On Sat, 12 Sep 2015, Roland Weber wrote: > Hi Alan, > > I'm sending a "Reply to all" on this mail. Should I continue to keep > Mathias and Bjorn on copy and cross-posting to linux-pci@ (I'm not > yet subscribed there, so that post probably won't get through anyway)? Most kernel lists don't require posters to subscribe. Yes, please keep everybody on the CC: list. > > [Roland, what happens if you try unbinding xhci-hcd before ehci-hcd? > > Note that unbinding xhci-hcd will cause your wireless keyboard & mouse > > to stop working, so you'll have to use a shell script or a network > > login to run the test.] > > The outcome is the same, the system freezes on the readl. > See below for the transcript from a screen photo. > > > I say this may be relevant because Roland found that ehci-hcd was > > unable to communicate over the USB bus if it tried to do so before > > xhci-hcd was probed. This happens in the 3.17 or earlier kernel -- and > > that kernel doesn't suffer the freeze problem. > > I can also produce the freeze on 3.17, with some extra steps: Okay, that's worth knowing. > (after boot there's just the ehci-pci bus with no device) > - unbind ehci-pci > - bind ehci-pci During both the unbind and the bind, the debugging lines you added to ehci-hcd.c should show up. Do they? > (now the ehci-pci bus has the missing device) > - unbind ehci-pci > > So the only reason why the older kernels didn't freeze is that > the device in question couldn't be initialized with the original > probe sequence. I'll try your blacklisting tip over the weekend. I wouldn't call it the "only reason". Rather, it's another symptom arising from the same underlying problem. 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
