linux-kernel - Re: [PATCH] usb: musb: remove unused variable 'devctl'

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Date:   Wed, 18 Nov 2020 12:48:54 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     min.guo@...iatek.com
Cc:     Bin Liu <b-liu@...com>, Matthias Brugger <matthias.bgg@...il.com>,
        chunfeng.yun@...iatek.com, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH] usb: musb: remove unused variable 'devctl'

On Tue, Nov 17, 2020 at 04:21:25PM +0800, min.guo@...iatek.com wrote:
> From: Min Guo <min.guo@...iatek.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@...iatek.com>
> ---
>  drivers/usb/musb/musbhsdma.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/usb/musb/musbhsdma.c b/drivers/usb/musb/musbhsdma.c
> index 0aacfc8be5a1..7acd1635850d 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
> @@ -336,8 +334,6 @@ irqreturn_t dma_controller_irq(int irq, void *private_data)
>  						< musb_channel->len) ?
>  					"=> reconfig 0" : "=> complete");
>  
> -				devctl = musb_readb(mbase, MUSB_DEVCTL);

Are you sure that the hardware does not require this read to complete
the command?  Lots of hardware is that way, so be very careful about
this.  Did you test it?

thanks,

greg k-h