On Tue, 26 Jun 2007, Jüri Reitel wrote: > Hello. > How to correctly turn off the port power of usb hub (assuming hub > supports individual port power switching). Correctly means that all > drivers using the device on that port are notified before the power is > removed. Removed device could also be a usb hub. > > My experiments with function > usb_control_msg( > hdev, usb_sndctrlpipe(hdev, 0), > USB_REQ_CLEAR_FEATURE, > USB_RT_PORT, > USB_PORT_FEAT_POWER, > port1, > NULL, 0, 1000); > > will not give desired results. > When I try to turn off port power with usb_control_msg, the port resides > on usb hub (not root hub), then the power is indeed switched off but > drivers are not notified.
You don't just want to notify the drivers; you want to destroy the entire device data structure. The only way to do it is to acquire the hub's device lock and call usb_disconnect() in hub.c. (Note that usb_disconnect is not EXPORT'ed.) Then turn off the USB_PORT_FEAT_C_CONNECTION and USB_PORT_FEAT_C_ENABLE status bits for that port in the hub and release the hub's lock. > The devices I use are usb 1.1 and 2.0 mass > storage devices, linux kernel 2.6.18. After the feat power feature was > cleared the power went away for a couple of seconds but then (i think > this was the scsi subsystem who wanted to perform IO with the device) > usb subsystem found logical disconnect on port and the device was > re-powered... Things get more complicated if port power must be switched > off on root hub that has kind of controller where each port is shared by > ohci - ehci driver. Most 2.0 pci to usb root hubs fall to that category. > If the port is used by both drivers (actually the sharing starts from > hardware) then the power must be turned off (port power feature cleared) > on both controllers. I don't know the generic solution how to set up > port mapping, except looking to the datasheet. Things are much worse with root hubs. In general they do _not_ support port power switching. > My question is how can I notify all drivers related to given usb hub > port when i have (struct usb_device *dev) > where dev is the device on hub port where the power must be switched off? usb_disconnect() will notify all those drivers for you. Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
