Re: [PATCH V2 5/7] USB: serial: f81232: Set F81534A serial port with RS232 mode

From: Ji-Ze Hong (Peter Hong)
Date: Thu Oct 24 2019 - 04:52:07 EST

Hi Johan,

Johan Hovold æ 2019/10/23 äå 07:53 åé:
On Mon, Sep 23, 2019 at 10:24:47AM +0800, Ji-Ze Hong (Peter Hong) wrote:
The Fintek F81532A/534A/535/536 is USB-to-2/4/8/12 serial ports device
and the serial ports are default disabled. Each port contains max 3 pins
GPIO and the 3 pins are default pull high with input mode.

When the serial port had activated (running probe()), we'll transform the
3 pins from GPIO function publicly to control Tranceiver privately use.

I'm not sure I understand what you're saying here.

We'll default set to 0/0/1 for control transceiver to RS232 mode.

Otherwise, If the serial port is not active, the 3 pins is in GPIO mode
and controlled by global GPIO device with VID/PID: 2c42/16f8.

Does this mean that you can control the three GPIOs either through the
serial device or through the gpio-control device (which are two separate
USB devices)?

Yes, when 1 F81534A connect to Host, it'll report device as following.
virtual HUB
GPIO Device.
serial port 1
serial port n

The link are F81534A pin-out:

So we can control F81534A series all GPIO pins via GPIO Device.
Serial ports are also control MODE0_x, MODE1_x, MODE2_x
(e.g. UART1 MODE0_1, MODE1_1, MODE2_1), but when Serial ports
is h/w disabled (DTR pull low), the mode pin will change to GPIO pin.

Ok, so you reset the tranceiver config on every probe.

Are the three GPIOs always connected to one particular tranceiver, or
are they truly general purpose?

In the latter case, it doesn't seem like a good idea to drive pins 0
and 1 low here as you have know idea what they're used for.

If we want to change the mode pin to GPIO pin, it need do h/w disable.
It the serial ports are activated, the 3 pin will be mode pin and set
default 0/0/1 to RS232 mode due to this driver not implement RS422/485

With Best Regards,
Peter Hong