linux-kernel - Re: [PATCH] tty: omap-serial: remove set but unused variable

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Message-ID: <ad64f294-2d45-b65d-a861-f4c494909afe@huawei.com>
Date:   Fri, 6 Dec 2019 15:11:10 +0800
From:   Xiongfeng Wang <wangxiongfeng2@...wei.com>
To:     Jiri Slaby <jslaby@...e.com>, Greg KH <gregkh@...uxfoundation.org>
CC:     <linux-serial@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <huawei.libin@...wei.com>, <shubhrajyoti@...com>,
        "balbi@...com >> Felipe Balbi" <balbi@...com>
Subject: Re: [PATCH] tty: omap-serial: remove set but unused variable



On 2019/12/5 20:39, Jiri Slaby wrote:
> On 05. 12. 19, 13:30, Xiongfeng Wang wrote:
>>
>>
>> On 2019/12/5 20:13, Greg KH wrote:
>>> On Thu, Dec 05, 2019 at 08:04:36PM +0800, Xiongfeng Wang wrote:
>>>> Fix the following warning:
>>>> drivers/tty/serial/omap-serial.c: In function serial_omap_rlsi:
>>>> drivers/tty/serial/omap-serial.c:496:16: warning: variable ch set but not used [-Wunused-but-set-variable]
>>>>
>>>> Reported-by: Hulk Robot <hulkci@...wei.com>
>>>> Signed-off-by: Xiongfeng Wang <wangxiongfeng2@...wei.com>
>>>> ---
>>>>  drivers/tty/serial/omap-serial.c | 3 +--
>>>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
>>>> index 6420ae5..54ee3ae 100644
>>>> --- a/drivers/tty/serial/omap-serial.c
>>>> +++ b/drivers/tty/serial/omap-serial.c
>>>> @@ -493,10 +493,9 @@ static unsigned int check_modem_status(struct uart_omap_port *up)
>>>>  static void serial_omap_rlsi(struct uart_omap_port *up, unsigned int lsr)
>>>>  {
>>>>  	unsigned int flag;
>>>> -	unsigned char ch = 0;
>>>>  
>>>>  	if (likely(lsr & UART_LSR_DR))
>>>> -		ch = serial_in(up, UART_RX);
>>>> +		serial_in(up, UART_RX);
>>>
>>> Shouldn't you be doing something with 'ch'?
>>
>> Sorry, my original thought is trying not to modify the existing logic.
>> I will look into the mechanism to see if I need to check 'ch'.
> 
> The change looks in fact correct, see:
> commit 9a12fcf8b1543c99ffcec3d61db86f0dea52dc9d
> Author: Shubhrajyoti D <shubhrajyoti@...com>
> Date:   Fri Sep 21 20:07:19 2012 +0530
> 
>     serial: omap: fix the reciever line error case
> 
> It also says: "This is recommended in the interrupt reset method in the
> table 23-246 of the omap4 TRM."
> 
> The character read is erroneous and should be apparently dropped. But
> you should add a comment about it, though.

Thanks a lot. I will add it in the comment and send another version.

Thanks,
Xiongfeng

> 
> thanks,
>