On Mon, 16 Apr 2012, Stephen Warren wrote: > >> The EHCI controller's active_kids count stays at 1 all the time. I > >> assume that's the root USB hub device. Looking in its power/ directory, > >> I see that even when nothing is plugged in, runtime_status==enabled, > >> even with no active_kids or runtime_usage: > > > > That does indeed sound like a bug. > > > >> [ 242.611209] usb 3-1: USB disconnect, device number 4 > >> root@ilyich:/sys/devices/tegra-ehci.2/usb3/power# cat async > >> enabled > >> root@ilyich:/sys/devices/tegra-ehci.2/usb3/power# cat autosuspend_delay_ms > >> 0 > > > > Odd... This should contain 2000. Maybe some userspace program has > > changed it? Either value would be okay, however. > > > > You could try writing 2000 to this file, then plugging in a device and > > unplugging it. The root hub should then suspend 2 seconds after you > > unplug the device. > > There's no difference if I write 2000 to this file. > > I've tried turning on dynamic debug for the entire of USB. None of those > fire, which I believe implies there aren't any attempted suspends of the > Tegra EHCI controller that fail. I also added a few extra printks to the > Tegra EHCI controller's suspend/resume functions which don't fire. > > Is this anything to do with it: > > ./ehci-hub.c:615: /* FIXME autosuspend idle root hubs */ No, that's a very old, fossil comment. It should have been removed years ago. > I'm at a loss how to do anything more useful here. We need to find out why the root hub isn't suspending. Can you do some debugging in drivers/usb/core/driver.c? The routines to check are autosuspend_check(), usb_runtime_idle(), and usb_runtime_suspend(). In particular, if autosuspend_check() doesn't return 0, what is the reason? And if it does, what does the usb_suspend_both() call return? 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
