On Fri, Oct 26, 2012 at 10:32:05AM +0530, shashank chaturvedi wrote: > >Why would you want to do that? For link power management? What is the > >xHCI kernel driver not providing you such that you have to write a > >userspace program? > > I want to do this for link power managment.But i am able to read & write > the PORTPMSC register (as per xhci spec 5.4.9) from userspace program.Why > not the PORTSC regsiter? Do NOT do this from userspace! You need to modify the xHCI kernel driver to support link PM for your host controller. The USB core has specific times it disables link PM (e.g. before a device is reset) and some drivers may require link PM to be disabled. You are circumventing kernel policy by writing the link PM registers from userspace. Do NOT do this! 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
