On Wed, Jun 30, 2010 at 10:16:16AM -0400, Alan Stern wrote: > On Wed, 30 Jun 2010, Oliver Neukum wrote: > > > Am Mittwoch, 30. Juni 2010, 11:04:58 schrieb Samuel Xu: > > > Q3: How to tell USB device?s suspension state? > > > > You don't. You can just query whether the device should autosuspend itself > > in /sys/bus/usb/devices/$DEVICE/power > > Starting with 2.6.35-rc1, if your kernel has CONFIG_PM_ADVANCED_DEBUG > enabled then you can tell a USB device's suspension state by reading > the device's power/runtime_status sysfs attribute file. Why make this file only available with a config option turned on? It would be useful for something like powertop to show that a USB device is actually suspended. You can guess if a device is suspending by looking at the connected_duration and active_duration file values, but this is less than ideal. Sarah Sharp -- 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
