Re: [PATCH 3/3 v6] tty/serial/8250: use mctrl_gpio helpers

[Stefan Roese]

On 17.06.19 11:51, Yegor Yefremov wrote:

<snip>
@@ -1944,11 +1948,15 @@ unsigned int serial8250_do_get_mctrl(struct uart_port 
*port)
  {
         struct uart_8250_port *up = up_to_u8250p(port);
         unsigned int status;
+       unsigned int val = 0;

         serial8250_rpm_get(up);
         status = serial8250_modem_status(up);
         serial8250_rpm_put(up);

+       if (up->gpios)
+               return mctrl_gpio_get(up->gpios, &val);
+

What happens when you have a mixed setup i.e. CTS controlled by UART
but other status pins controlled by GPIO? In this case CTS status
won't be returned. Do I see it right?

Yes, your analysis does seem to be correct. Please note that I did
not intentionally did change it this way. I was not thinking about
such a "mixed design".
 
What about something like this:

unsigned int serial8250_do_get_mctrl(struct uart_port *port)
   {
           struct uart_8250_port *up = up_to_u8250p(port);
           unsigned int status;
           unsigned int val;

           serial8250_rpm_get(up);
           status = serial8250_modem_status(up);
           serial8250_rpm_put(up);

           val = serial8250_MSR_to_TIOCM(status);
           if (up->gpios)
                   mctrl_gpio_get(up->gpios, &val);

           return val;
   }

Looks good to me, thanks. Do you have such a setup with some modem
control signal handled via GPIO and some via the UART? Could you
test such a change?

Thanks,
Stefan