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

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Date:   Wed, 2 Dec 2020 11:16:02 +0800
From:   jiladahe1997 <jiladahe1997@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>
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 2020/12/2 0:47, Greg KH wrote:
> 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
Yeah, checkpatch didn't complain:


root@...zefbvkcoj7o7ledf4oqZ:~/workspace/linux-imx$
./scripts/checkpatch.pl 
0001-tty-serial-imx-Enable-TXEN-bit-in-imx_poll_init.patch
total: 0 errors, 0 warnings, 8 lines checked

0001-tty-serial-imx-Enable-TXEN-bit-in-imx_poll_init.patch has no
obvious style problems and is ready for submission.


Maybe some patches should be submitted to checkpatch.pl :).

Anyway, I will add  ' '  characters and send PATCH V2.


Thanks,

Mingrui Ren