On Tue, 29 Nov 2016, Changming Huang wrote: > The EHCI specification states the following in the SUSP bit description: > In the Suspend state, the port is sensitive to resume detection. > Note that the bit status does not change until the port is suspended and > that there may be a delay in suspending a port if there is a transaction > currently in progress on the USB. > > However, in NXP USBDR controller, the PORTSCx[SUSP] bit changes immediately > when the application sets it and not when the port is actually suspended. > > So the application must wait for at least 10 milliseconds after a port > indicates that it is suspended, to make sure this port has entered > suspended state before initiating this port resume using the Force Port > Resume bit. This bit is for NXP controller, not EHCI compatible. > > Signed-off-by: Changming Huang <jerry.huang@xxxxxxx> > Signed-off-by: Ramneek Mehresh <ramneek.mehresh@xxxxxxx> > --- > Changes in v4: > - release spinlock before sleeping > Changes in v3: > - add 10ms delay in function ehci_hub_control > - fix typos > Changes in v2: > - move sleep out of spin-lock > - add more comment for this workaround Acked-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> -- 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
