linux-kernel - Re: [PATCH V1 1/2] usb:serial: Implement Fintek F81232 break on/off

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Message-ID: <20170109151409.GQ21536@localhost>
Date:   Mon, 9 Jan 2017 16:14:09 +0100
From:   Johan Hovold <johan@...nel.org>
To:     "Ji-Ze Hong (Peter Hong)" <hpeter@...il.com>
Cc:     johan@...nel.org, gregkh@...uxfoundation.org,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        tom_tsai@...tek.com.tw, peter_hong@...tek.com.tw,
        hpeter+linux_kernel@...il.com
Subject: Re: [PATCH V1 1/2] usb:serial: Implement Fintek F81232 break on/off

On Fri, Dec 09, 2016 at 01:39:33PM +0800, Ji-Ze Hong (Peter Hong) wrote:
> Implement Fintek F81232 break on/off with LCR register,
> it's the same with 16550A LCR register layout.
> 
> Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@...il.com>
> ---
>  drivers/usb/serial/f81232.c | 40 ++++++++++++++++++++++++++++++++++------
>  1 file changed, 34 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/usb/serial/f81232.c b/drivers/usb/serial/f81232.c
> index 972f5a5..d45a70e 100644
> --- a/drivers/usb/serial/f81232.c
> +++ b/drivers/usb/serial/f81232.c
> @@ -131,6 +131,21 @@ static int f81232_set_register(struct usb_serial_port *port, u16 reg, u8 val)
>  	return status;
>  }
>  
> +static int f81232_set_mask_register(struct usb_serial_port *port, u16 reg,
> +						u8 mask, u8 val)
> +{
> +	int status;
> +	u8 tmp;
> +
> +	status = f81232_get_register(port, reg, &tmp);
> +	if (status)
> +		return status;
> +
> +	tmp = (tmp & ~mask) | (val & mask);
> +
> +	return f81232_set_register(port, reg, tmp);
> +}
> +
>  static void f81232_read_msr(struct usb_serial_port *port)
>  {
>  	int status;
> @@ -335,15 +350,27 @@ static void f81232_process_read_urb(struct urb *urb)
>  	tty_flip_buffer_push(&port->port);
>  }
>  
> +static void f81232_set_break(struct usb_serial_port *port, bool enable)
> +{
> +	int status;
> +	u8 tmp = 0;
> +
> +	if (enable)
> +		tmp = UART_LCR_SBC;
> +
> +	status = f81232_set_mask_register(port, LINE_CONTROL_REGISTER,
> +				UART_LCR_SBC, tmp);
> +	if (status) {
> +		dev_err(&port->dev, "%s: set break failed: %x\n", __func__,

You want %d here.

And you can drop the __func__ prefix.

> +				status);
> +	}

You should also coordinate this with the LCR update in set_termios,
otherwise changing line settings would clear break etc.

> +}
> +
>  static void f81232_break_ctl(struct tty_struct *tty, int break_state)
>  {
> -	/* FIXME - Stubbed out for now */
> +	struct usb_serial_port *port = tty->driver_data;
>  
> -	/*
> -	 * break_state = -1 to turn on break, and 0 to turn off break
> -	 * see drivers/char/tty_io.c to see it used.
> -	 * last_set_data_urb_value NEVER has the break bit set in it.
> -	 */
> +	f81232_set_break(port, break_state);
>  }
>  
>  static void f81232_set_baudrate(struct usb_serial_port *port, speed_t baudrate)
> @@ -563,6 +590,7 @@ static void f81232_close(struct usb_serial_port *port)
>  	f81232_port_disable(port);
>  	usb_serial_generic_close(port);
>  	usb_kill_urb(port->interrupt_in_urb);
> +	f81232_set_break(port, false);

I don't think this is needed, and then you can fold set_break into
break_ctl above as well.

>  }
>  
>  static void f81232_dtr_rts(struct usb_serial_port *port, int on)

Thanks,
Johan