| Message ID | 20191107132904.2379-3-johan@kernel.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 1c333550ea92a9c7a5fdf0f3474eba3387478f20 |
| Headers | show |
| Series | USB: serial: mos7840: type detection and clean ups | expand |
diff --git a/drivers/usb/serial/mos7840.c b/drivers/usb/serial/mos7840.c index f13cf723fa6c..6de41a3c2dab 100644 --- a/drivers/usb/serial/mos7840.c +++ b/drivers/usb/serial/mos7840.c @@ -1955,6 +1955,13 @@ static int mos7840_ioctl(struct tty_struct *tty, return -ENOIOCTLCMD; } +/* + * Check if GPO (pin 42) is connected to GPI (pin 33) as recommended by ASIX + * for MCS7810 by bit-banging a 16-bit word. + * + * Note that GPO is really RTS of the third port so this will toggle RTS of + * port two or three on two- and four-port devices. + */ static int mos7810_check(struct usb_serial *serial) { int i, pass_count = 0;
Document the MCS7810 detection hack which relies on having the GPO and GPI pins connected as recommended by ASIX. Note that GPO (pin 42) is really RTS of the third port which will be toggled for the corresponding physical port on two- and four-port devices. Signed-off-by: Johan Hovold <johan@kernel.org> --- drivers/usb/serial/mos7840.c | 7 +++++++ 1 file changed, 7 insertions(+)