Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 24 Nov 2020 08:24:58 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     min.guo@mediatek.com
Cc:     Bin Liu <b-liu@ti.com>, Alan Stern <stern@rowland.harvard.edu>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        chunfeng.yun@mediatek.com, linux-usb@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org
Subject: Re: [PATCH v2] usb: musb: remove unused variable 'devctl'
Message-ID: <X7y1SpiRE+CcBQIa@kroah.com>
References: <20201124063613.28796-1-min.guo@mediatek.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20201124063613.28796-1-min.guo@mediatek.com>
Precedence: bulk

On Tue, Nov 24, 2020 at 02:36:13PM +0800, min.guo@mediatek.com wrote:
> From: Min Guo <min.guo@mediatek.com>
> 
> Remove unused 'devctl' variable to fix compile warnings:
> 
>     drivers/usb/musb/musbhsdma.c: In function 'dma_controller_irq':
>     drivers/usb/musb/musbhsdma.c:324:8: warning: variable 'devctl' set
>     but not used [-Wunused-but-set-variable]
> 
> Signed-off-by: Min Guo <min.guo@mediatek.com>
> ---
> changes in v2
> suggested by Alan Stern:
> Add void before musb_read to indicate that the register MUSB_DEVCTL
> was intended to be read and discarded.
> ---
>  drivers/usb/musb/musbhsdma.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/musb/musbhsdma.c b/drivers/usb/musb/musbhsdma.c
> index 0aacfc8be5a1..f59a009c533e 100644
> --- a/drivers/usb/musb/musbhsdma.c
> +++ b/drivers/usb/musb/musbhsdma.c
> @@ -321,8 +321,6 @@ irqreturn_t dma_controller_irq(int irq, void *private_data)
>  				musb_channel->channel.status =
>  					MUSB_DMA_STATUS_BUS_ABORT;
>  			} else {
> -				u8 devctl;
> -
>  				addr = musb_read_hsdma_addr(mbase,
>  						bchannel);
>  				channel->actual_len = addr
> @@ -336,7 +334,7 @@ irqreturn_t dma_controller_irq(int irq, void *private_data)
>  						< musb_channel->len) ?
>  					"=> reconfig 0" : "=> complete");
>  
> -				devctl = musb_readb(mbase, MUSB_DEVCTL);
> +				(void)musb_readb(mbase, MUSB_DEVCTL);

Please put a comment here as to why the read is happening so that people
do not throw it away sometime in the future.

thanks,

greg k-h