On Thu, 11 May 2006, David Brownell wrote: > On Thursday 11 May 2006 10:07 am, Alan Stern wrote: > > Please reply to the mailing list as well as to me. > > > > On Thu, 11 May 2006, rakesh kn wrote: > > > > > Hi, > > > In the suspend/resume call back in platform driver structure, i am > > > exactly doing the same, > > > i call bus_suspend to suspend all the ports in the controller. and the > > > i halt the controller. > > > This is what is done in the suspend call back. > > > > > > Then which function/call back is invoked when we try to suspend/resume > > > from the /sys/bus/usb/devices/usb1/power/state . > > > > Writing to that file doesn't invoke anything. > > Not so. That's the device representing the root hub (representing all > the downstream usb links), as distinct from the interface for the root hub > (used to control individual downstream links) or the host controller (for > the upstream links, such as PCI or some other bus).
Let's be more precise. Writing a positive value to /sys/bus/usb/devices/usb1/power/state will invoke usb_generic_suspend() in drivers/usb/core/usb.c. That routine will call usb_suspend_device() in drivers/usb/core/hub.c. If CONFIG_USB_SUSPEND isn't set, that routine will return without calling anything else. If CONFIG_USB_SUSPEND _is_ set, that routine will call __usb_suspend_device() in drivers/usb/core/hub.c. Then that routine will return without calling anything else. Either way, none of the suspend routines in the host controller driver will be invoked. A similar analysis applies when you write a 0 to /sys/.../power/state, although it differs because usbcore will automatically resume the root hub interface. So it will call hub_resume() in drivers/usb/core/hub.c, which will call hcd_bus_resume() in drivers/usb/core/hcd.c, which will call hcd->driver->bus_resume(). So for resuming, one of the host controller driver's resume routines does get invoked. Alan Stern ------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
