linux-kernel - RE: [EXT] [PATCH v1 1/3] tty: serial: lpuart: Remove unnecessary code from set

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Date:   Thu, 17 Oct 2019 05:13:14 +0000
From:   Andy Duan <fugang.duan@....com>
To:     Philippe Schenker <philippe.schenker@...adex.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>
CC:     Max Krummenacher <max.krummenacher@...adex.com>,
        Jiri Slaby <jslaby@...e.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Stefan Agner <stefan@...er.ch>,
        dl-linux-imx <linux-imx@....com>,
        Andrey Smirnov <andrew.smirnov@...il.com>
Subject: RE: [EXT] [PATCH v1 1/3] tty: serial: lpuart: Remove unnecessary code
 from set_mctrl

From: Philippe Schenker <philippe.schenker@...adex.com> Sent: Wednesday, October 16, 2019 11:19 PM
> Currently flow control is not working due to lpuart32_set_mctrl that is
> clearing TXCTSE bit in all cases. This bit gets earlier setup by
> lpuart32_set_termios.
> 
> As I read in Documentation set_mctrl is also not meant for hardware flow
> control rather than gpio setting and clearing a RTS signal.
> Therefore I guess it is safe to remove the whole code in lpuart32_set_mctrl.
> 
> This was tested with console on a i.MX8QXP SoC.
> 
> Signed-off-by: Philippe Schenker <philippe.schenker@...adex.com>

Reviewed-by: Fugang Duan <fugang.duan@....com>
> ---
> 
>  drivers/tty/serial/fsl_lpuart.c | 11 -----------
>  1 file changed, 11 deletions(-)
> 
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index
> 537896c4d887..f3271857621c 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -1333,18 +1333,7 @@ static void lpuart_set_mctrl(struct uart_port
> *port, unsigned int mctrl)
> 
>  static void lpuart32_set_mctrl(struct uart_port *port, unsigned int mctrl)  {
> -       unsigned long temp;
> -
> -       temp = lpuart32_read(port, UARTMODIR) &
> -                       ~(UARTMODIR_RXRTSE |
> UARTMODIR_TXCTSE);
> -
> -       if (mctrl & TIOCM_RTS)
> -               temp |= UARTMODIR_RXRTSE;
> -
> -       if (mctrl & TIOCM_CTS)
> -               temp |= UARTMODIR_TXCTSE;
> 
> -       lpuart32_write(port, temp, UARTMODIR);
>  }
> 
>  static void lpuart_break_ctl(struct uart_port *port, int break_state)
> --
> 2.23.0