linux-kernel - Re: [PATCH 27/36] tty: synclinkmp: Mark never checked 'readval' as __always

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Date:   Thu, 5 Nov 2020 09:28:00 +0100
From:   Jiri Slaby <jirislaby@...nel.org>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     linux-kernel@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        paulkf@...rogate.com
Subject: Re: [PATCH 27/36] tty: synclinkmp: Mark never checked 'readval' as
 __always_unused

On 04. 11. 20, 20:35, Lee Jones wrote:
> Fixes the following W=1 kernel build warning(s):
> 
>   drivers/tty/synclinkmp.c: In function ‘init_adapter’:
>   drivers/tty/synclinkmp.c:5167:6: warning: variable ‘readval’ set but not used [-Wunused-but-set-variable]
> 
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Jiri Slaby <jirislaby@...nel.org>
> Cc: paulkf@...rogate.com
> Signed-off-by: Lee Jones <lee.jones@...aro.org>
> ---
>   drivers/tty/synclinkmp.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/synclinkmp.c b/drivers/tty/synclinkmp.c
> index 0ca738f61a35b..75f494bfdcbed 100644
> --- a/drivers/tty/synclinkmp.c
> +++ b/drivers/tty/synclinkmp.c
> @@ -5165,7 +5165,7 @@ static bool init_adapter(SLMP_INFO *info)
>   
>   	/* Set BIT30 of Local Control Reg 0x50 to reset SCA */
>   	volatile u32 *MiscCtrl = (u32 *)(info->lcr_base + 0x50);
> -	u32 readval;
> +	u32 __always_unused readval;

Why not just remove readval completely as in other cases?

And the loop can be turned into ndelay:

         /*
          * Force at least 170ns delay before clearing
          * reset bit. Each read from LCR takes at least
          * 30ns so 10 times for 300ns to be safe.
          */
         for(i=0;i<10;i++)
                 readval = *MiscCtrl;


thanks,
-- 
js
suse labs