On Fri, 25 Jul 2014, Michael Welling wrote: > On Fri, Jul 25, 2014 at 10:02:15AM -0400, Alan Stern wrote: > > On Thu, 24 Jul 2014, Michael Welling wrote: > > > > > So I may be barking up the wrong tree on this one. > > > > > > Today I discovered something that may lead to the resolution of my issue. > > > > > > The hardware I am using incorporates a USB switch on-board to avoid the > > > having an external switch to plug in keyboards etc. If two devices are plugged > > > into the downstream ports they are both detected on boot. When I unplug > > > one of the devices and plug it back in, it is detected again. > > > > > > As long as one downstream device ports is populated the device discovery works > > > on the other. Any clue on this? > > > > > > This reminded of a note that I made on the schematic after talking to SMSC. > > > > > > Set "UseExternalVbus Indicator" BIT 7 in register 0x0a. > > > > > > This is a PHY register that may actually be accessible in > > > drivers/usb/phy/phy-ulpi.c > > > but it looks like I cannot access the code from device tree. > > > > > > What would be the best way to go about adding support for this? > > > > Maybe you would learn more if you enabled USB debugging in your kernel. > > Or if you used usbmon to see what the USB traffic is doing. > > The trafic stops all together when both USB devices are unplugged for > the first time. > > The external USB HUB is still present in the device list but it does not > detect anything after the last disconnect. What if you prevent the root hub from going into runtime suspend? Or prevent the external hub from going into runtime suspend? You could be facing a wakeup 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
