On Sat, 9 May 2009, Andrew Savchenko wrote: > Hello, > > I use vanilla kernel-2.6.29.2, it is configured with CONFIG_USB_SUSPEND=y, > but autosuspend is enabled only for host controllers, and not for attached > devices. (For attached hubs, actually, not just host controllers). Yes, it is done that way on purpose. > Of course I can enable autosuspend manually: > But this should be done every single time after device plug-in. Currently I use > udev for this task, but it looks like an ugly hack. Is there any better way to > handle this? I don't know. In theory programs like hal should take care of this for you, but I'm not aware of how much progress has been made in this direction. > IMO if kernel is configured with USB power saving enabled, it > *should* be enabled by default. Is there any reason to avoid this? Yes indeed. A large percentage -- hard to estimate, but more than large enough to cause widespread problems -- of USB devices can't handle being suspended. They just die. If the kernel automatically suspended every USB device when it wasn't in use, there would be loud and voluminous complaints. I know, because the kernel used to work that way -- and there were! That was back around 2.6.22 or earlier; see http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=7d2c592609a7da950b458403f1936d382f38ff9c 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
