On Mon, 6 Aug 2012, Sarah Sharp wrote: > Hi Alan and Rafael, > > Is there a reason why runtime PM is disabled by default for PCI USB host > controllers? It would really be nice to have this turned on by default > at boot, rather than running udev scripts or powertop. As far as I know, the only reason is that runtime PM is disabled by default for _all_ devices, unless the subsystem or driver specifically enables it. Nobody has submitted a patch enabling runtime PM for PCI USB host controllers. > Are there PCI USB hosts that can't handle D3? Or something else > preventing us from turning runtime PM on by default? I'm not aware of any such problems. But that doesn't mean they don't exist -- it wouldn't be surprising if you start getting complaints when you enable runtime PM by default. I guess the only way to find out is to try. It's not a hard change; just call pm_runtime_allow(&dev->dev) just before the normal return in usb_hcd_pci_probe(). 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
