On Thu, Nov 07, 2013 at 10:32:33AM -0500, Alan Stern wrote: > On Wed, 6 Nov 2013, Julius Werner wrote: > > > > What if the device is in USB_STATE_SUSPENDED? > > > > I'm not sure that is possible at that point in hub_events(), I don't > > know of a way that could lead to this situation. I could still add the > > check just to be sure if you want it, though. > > I don't know either. But Sarah has said that ports can spontaneously > go into Compliance Mode for no apparent reason. If that can happen, > maybe it can happen while the port is in U3 and the device is > suspended. In such cases, though, you'd need to do a reset-resume > rather than a simple reset. Looking at commits c3897aa5386faba77e5bbdf94902a1658d3a5b11 and 71c731a296f1b08a3724bd1b514b64f1bda87a23, it seems that the TI host controllers' ports can go into compliance mode only when a device is inserted. Once the device is link trained by the redriver, the port shouldn't go into compliance mode. So we should never see compliance mode on a port with an attached USB device in suspend. Alex, can you confirm that the TI host's port won't go into compliance mode while a connected device is suspended? > > > Not at all. If a device is unplugged, its state changes to NOTATTACHED > > > before the driver is unbound. During that time, the driver will see > > > all its URBs failing, so it may very well try to reset the device. > > > (For example, usbhid behaves like this.) That isn't a bug. > > > > Oh, okay, I wasn't quite sure how that plays together. Would you think > > it's still valuable to print it out (maybe as dev_info() instead of > > dev_warn()) instead of just silently ignoring the reset request? It > > would have certainly been useful for me to find this problem faster, > > but I can take it out again if you think it would result in too much > > noise. > > I think keeping dev_dbg() is best. If you're searching for the > solution to a problem, you should have debugging enabled and so you > ought to see the message. > > 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
