linux-kernel - RE: [PATCH] tty: serial: fsl_lpuart: fix lpuart32_poll_get

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Message-ID: <AM8PR04MB73157339D0AC240C3DAAD64BFF320@AM8PR04MB7315.eurprd04.prod.outlook.com>
Date:   Tue, 29 Sep 2020 09:36:23 +0000
From:   Andy Duan <fugang.duan@....com>
To:     Peng Fan <peng.fan@....com>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "jirislaby@...nel.org" <jirislaby@...nel.org>,
        "andrew.smirnov@...il.com" <andrew.smirnov@...il.com>
CC:     "linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH] tty: serial: fsl_lpuart: fix lpuart32_poll_get_char

From: Peng Fan <peng.fan@....com> Sent: Tuesday, September 29, 2020 5:55 PM
> The watermark is set to 1, so we need to input two chars to trigger RDRF using
> the original logic. With the new logic, we could always get the char when there
> is data in FIFO.
> 
> Suggested-by: Fugang Duan <fugang.duan@....com>
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
>  drivers/tty/serial/fsl_lpuart.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index
> 645bbb24b433..1c37280b6c0c 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -680,7 +680,7 @@ static void lpuart32_poll_put_char(struct uart_port
> *port, unsigned char c)
> 
>  static int lpuart32_poll_get_char(struct uart_port *port)  {
> -	if (!(lpuart32_read(port, UARTSTAT) & UARTSTAT_RDRF))
> +	if (!(lpuart32_read(port, UARTWATER) >>  UARTWATER_RXCNT_OFF))

Please remove redundant blank space.

>  		return NO_POLL_CHAR;
> 
>  	return lpuart32_read(port, UARTDATA);
> --
> 2.28.0