linux-kernel - Re: [PATCH RESEND] tty/serial/imx: Enable TXEN bit in imx_poll

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Message-ID: <X8Zznz7950E8R+Ol@kroah.com>
Date:   Tue, 1 Dec 2020 17:47:27 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     jiladahe1997 <jiladahe1997@...il.com>
Cc:     shawnguo@...nel.org, s.hauer@...gutronix.de, linux-imx@....com,
        linux-kernel@...r.kernel.org, 972931182@...com
Subject: Re: [PATCH RESEND] tty/serial/imx: Enable TXEN bit in
 imx_poll_init().

On Wed, Dec 02, 2020 at 07:03:08AM +0800, jiladahe1997 wrote:
> From: Mingrui Ren <jiladahe1997@...il.com>
> 
> As described in Documentation, poll_init() is called by kgdb to initialize
> hardware which supports both poll_put_char() and poll_get_char().
> 
> It's necessary to enable TXEN bit, otherwise, it will cause hardware fault
> and kernel panic when calling imx_poll_put_char().
> 
> Generally, if use /dev/ttymxc0 as kgdb console as well as system
> console, ttymxc0 is initialized early by system console which does enable
> TXEN bit.But when use /dev/ttymxc1 as kgbd console, ttymxc1 is only
> initialized by imx_poll_init() cannot enable the TXEN bit, which will
> cause kernel panic.
> 
> Signed-off-by: Mingrui Ren <jiladahe1997@...il.com>
> ---
> Hi, thanks for your reply, and sorry for sending two identical emails.
> The email service I used before seems to have some problems, 
> so I switched to gmail.This is the "correct" version, please check.
> 
>  drivers/tty/serial/imx.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index 43c6d7142fdd..7c665db3d897 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -1829,7 +1829,7 @@ static int imx_uart_poll_init(struct uart_port *port)
>  	ucr1 |= UCR1_UARTEN;
>  	ucr1 &= ~(UCR1_TRDYEN | UCR1_RTSDEN | UCR1_RRDYEN);
>  
> -	ucr2 |= UCR2_RXEN;
> +	ucr2 |= UCR2_RXEN|UCR2_TXEN;

Didn't checkpatch complain about this?  Please use ' ' characters around
the '|' character.

thanks,

greg k-h