linux-kernel - Re: [PATCH] tty: max3100: remove unused variable rts and remove unused assignment

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Date:   Thu, 2 Nov 2017 14:21:27 +0000
From:   Colin Ian King <colin.king@...onical.com>
To:     wharms@....de
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, linux-serial@...r.kernel.org,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tty: max3100: remove unused variable rts and remove
 unused assignment

On 02/11/17 14:14, walter harms wrote:
> 
> 
> Am 02.11.2017 15:01, schrieb Colin King:
>> From: Colin Ian King <colin.king@...onical.com>
>>
>> Variable rts is being assigned but it is never read, hence it can be
>> removed.  The assignment to param_new to zero is redundant as it is
>> being updates a few statements later, so remove this redundant
>> assignment. Cleans up two clang warnings:
>>
>> drivers/tty/serial/max3100.c:277:3: warning: Value stored to 'rts'
>> is never read
>> drivers/tty/serial/max3100.c:439:2: warning: Value stored to 'param_new'
>> is never read
>>
>> Signed-off-by: Colin Ian King <colin.king@...onical.com>
>> ---
>>  drivers/tty/serial/max3100.c | 4 +---
>>  1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/drivers/tty/serial/max3100.c b/drivers/tty/serial/max3100.c
>> index b6b3453e8c1f..f691f3cdb5b1 100644
>> --- a/drivers/tty/serial/max3100.c
>> +++ b/drivers/tty/serial/max3100.c
>> @@ -263,7 +263,7 @@ static void max3100_work(struct work_struct *w)
>>  	struct max3100_port *s = container_of(w, struct max3100_port, work);
>>  	int rxchars;
>>  	u16 tx, rx;
>> -	int conf, cconf, rts, crts;
>> +	int conf, cconf, crts;
>>  	struct circ_buf *xmit = &s->port.state->xmit;
>>  
>>  	dev_dbg(&s->spi->dev, "%s\n", __func__);
>> @@ -274,7 +274,6 @@ static void max3100_work(struct work_struct *w)
>>  		conf = s->conf;
>>  		cconf = s->conf_commit;
>>  		s->conf_commit = 0;
>> -		rts = s->rts;
>>  		crts = s->rts_commit;
>>  		s->rts_commit = 0;
>>  		spin_unlock(&s->conf_lock);
>> @@ -436,7 +435,6 @@ max3100_set_termios(struct uart_port *port, struct ktermios *termios,
>>  	dev_dbg(&s->spi->dev, "%s\n", __func__);
>>  
>>  	cflag = termios->c_cflag;
>> -	param_new = 0;
>>  	param_mask = 0;
>>  
>>  	baud = tty_termios_baud_rate(termios);
> 
> are you sure ?

Yep. So are my compilers

> 
> based on this code:
> https://lxr.missinglinkelectronics.com/linux/drivers/tty/serial/max3100.c

 438        cflag = termios->c_cflag;
 439        param_new = 0;
 440        param_mask = 0;
 441
 442        baud = tty_termios_baud_rate(termios);
 443        param_new = s->conf & MAX3100_BAUD;

param_new is being updated again on line 440, so line 439 is redundant.

> 
> the default case will not set param_new
> 
> re,
>  wh
> 
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