On Mon, 22 Apr 2013, Peter Chen wrote: > Hi all, > > Recently, I have several customers troubled in safe recover USB > function during the ESD situation (or some other situations, like > short dp/dm, ground dp/dm, etc). > > I designed the ESD detect and recovery process, but I met some > sync problems between host controller driver (eg, ehci) and class > driver (eg, mass storage). For example, when khubd tries to disconnect > usb device, it will try to stop thread usb-storage, but usb-storage > is waiting some transfers to finish, qTD and QH operation may be > finished (usb_submit_urb does not return error), but no watchdog timer > and completion interrupt are occurred. > > I have: > esd_detect_process and esd_recovery_process at host controller driver. > At esd_detect_porcess > It will disable usb interrupt and judge ASE and PSE, etc. > At esd_recovery_process: > It needs to reset controller (usbcmd.rst, and toggle portsc.pp bit, etc) > > I would like to have some synchronization mechanism between usb_submit_urb > or (ehci_urb_enqueue) and my esd_detect_process and esd_recovery_process. > But still not find a safe one, eg, I still met khubd's status changes > "D" problem described above. Any suggestions are appreciated, Thanks. Your recovery process should not need to make all these changes to ehci-hcd. Simply carry out the same actions as the "dead:" statement label in ehci_irq() -- that is, do the same thing as if an interrupt occurred with the STS_FATAL bit set. That code is all properly synchronized. Then unbind the driver from the controller and rebind it. Rebinding will reset the controller. 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
