linux-kernel - Re: [PATCH] serial: 8250_mtk: support big baud rate.

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Message-ID: <1472094906.19004.2.camel@mhfsdcap03>
Date:   Thu, 25 Aug 2016 11:15:06 +0800
From:   Long Cheng <long.cheng@...iatek.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
CC:     Jiri Slaby <jslaby@...e.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Eddie Huang <eddie.huang@...iatek.com>,
        Peter Hurley <peter@...leysoftware.com>,
        <linux-serial@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <srv_heupstream@...iatek.com>
Subject: Re: [PATCH] serial: 8250_mtk: support big baud rate.

On Fri, 2016-08-12 at 10:41 +0800, Long Cheng wrote:
> From: Eddie Huang <eddie.huang@...iatek.com>
> 
> mediatek can support baud rate up to 4M.
> the 'uart_get_baud_rate' function will limit the max baud rate.
> Modify max baud to remove the limit.
> 
> Signed-off-by: Long Cheng <long.cheng@...iatek.com>
> ---
>  drivers/tty/serial/8250/8250_mtk.c  |    6 +-----
>  drivers/tty/serial/8250/8250_port.c |    4 +---
>  2 files changed, 2 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_mtk.c b/drivers/tty/serial/8250/8250_mtk.c
> index 3611ec9..ce0cc47 100644
> --- a/drivers/tty/serial/8250/8250_mtk.c
> +++ b/drivers/tty/serial/8250/8250_mtk.c
> @@ -62,7 +62,7 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
>  	 */
>  	baud = uart_get_baud_rate(port, termios, old,
>  				  port->uartclk / 16 / 0xffff,
> -				  port->uartclk / 16);
> +				  port->uartclk);
>  
>  	if (baud <= 115200) {
>  		serial_port_out(port, UART_MTK_HIGHS, 0x0);
> @@ -76,10 +76,6 @@ mtk8250_set_termios(struct uart_port *port, struct ktermios *termios,
>  		quot = DIV_ROUND_UP(port->uartclk, 4 * baud);
>  	} else {
>  		serial_port_out(port, UART_MTK_HIGHS, 0x3);
> -
> -		/* Set to highest baudrate supported */
> -		if (baud >= 1152000)
> -			baud = 921600;
>  		quot = DIV_ROUND_UP(port->uartclk, 256 * baud);
>  	}
>  
> diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
> index 7481b95..c45c1e3 100644
> --- a/drivers/tty/serial/8250/8250_port.c
> +++ b/drivers/tty/serial/8250/8250_port.c
> @@ -2504,8 +2504,6 @@ static unsigned int serial8250_get_baud_rate(struct uart_port *port,
>  					     struct ktermios *termios,
>  					     struct ktermios *old)
>  {
> -	unsigned int tolerance = port->uartclk / 100;
> -
>  	/*
>  	 * Ask the core to calculate the divisor for us.
>  	 * Allow 1% tolerance at the upper limit so uart clks marginally
> @@ -2514,7 +2512,7 @@ static unsigned int serial8250_get_baud_rate(struct uart_port *port,
>  	 */
>  	return uart_get_baud_rate(port, termios, old,
>  				  port->uartclk / 16 / 0xffff,
> -				  (port->uartclk + tolerance) / 16);
> +				  port->uartclk);
>  }
>  
>  void

Ping? Any reaction to the above?

Regards, thanks.