Hello, It was observed that the GPIOs of the ftdi_sio driver cannot be used when the device was put into autosuspend earlier (usb_control_msg returns -EHOSTUNREACH). Quick workaround for users is to disable autosuspend only for this affected device, which reportedly fixes the problem. However, as the original contributor of this GPIO functionality, my goal is creating patch that automatically wakes the device and disables auto- suspend when (and only when) the user requests a GPIO line, thereby making sure that the GPIOs will be usable (which the user has already declared a demand for by requesting a line). Unfortunately, nothing I try in the kernel works. usb_autopm_get_interface() is called successfully (returns 0), but the device still goes into suspend (or does not wake if already suspended, dunno). I also tried usb_disable_autosuspend() but same results. So my question is: how can I wake a suspended usb-serial device and prevent it from going into autosuspend again (after probing ended)? AFAICT usb_autopm_get_interface() should do exactly this, but as I said above, for some reason it doesn't have the expected effect. Thank you for your help, Karoly
