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

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Message-ID: <20201120163727.GC619708@rowland.harvard.edu>
Date:   Fri, 20 Nov 2020 11:37:27 -0500
From:   Alan Stern <stern@...land.harvard.edu>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Min Guo <min.guo@...iatek.com>, 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 Fri, Nov 20, 2020 at 05:32:44PM +0100, Greg Kroah-Hartman wrote:
> On Fri, Nov 20, 2020 at 11:15:19AM -0500, Alan Stern wrote:
> > > Perhaps you might want to add a comment here so that people will not
> > > keep making this same mistake when they run auto-checkers on the
> > > codebase?
> > 
> > A better change would be
> > 
> > -			devctl = musb_readb(mbase, MUSB_DEVCTL);
> > +			(void) musb_readb(mbase, MUSB_DEVCTL);
> > 
> > and eliminate the unused variable.  Then there wouldn't be any compiler 
> > warning.
> 
> No need for the (void), the compiler shouldn't warn about that, right?

True, but it clearly indicates to a human reader that the value was 
intended to be read and thrown away.  Alternatively, the (void) cast 
could be left out and a comment added.

Alan Stern