From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CE758C63798 for ; Fri, 20 Nov 2020 16:15:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 53F0B223FD for ; Fri, 20 Nov 2020 16:15:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728628AbgKTQPU (ORCPT ); Fri, 20 Nov 2020 11:15:20 -0500 Received: from netrider.rowland.org ([192.131.102.5]:44073 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1728622AbgKTQPU (ORCPT ); Fri, 20 Nov 2020 11:15:20 -0500 Received: (qmail 619842 invoked by uid 1000); 20 Nov 2020 11:15:19 -0500 Date: Fri, 20 Nov 2020 11:15:19 -0500 From: Alan Stern To: Greg Kroah-Hartman Cc: Min Guo , Bin Liu , Matthias Brugger , 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] usb: musb: remove unused variable 'devctl' Message-ID: <20201120161519.GA619708@rowland.harvard.edu> References: <20201117082125.7619-1-min.guo@mediatek.com> <1605854930.3995.8.camel@mhfsdcap03> <1605858126.3995.14.camel@mhfsdcap03> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Fri, Nov 20, 2020 at 09:36:33AM +0100, Greg Kroah-Hartman wrote: > On Fri, Nov 20, 2020 at 03:42:06PM +0800, Min Guo wrote: > > On Fri, 2020-11-20 at 07:54 +0100, Greg Kroah-Hartman wrote: > > > On Fri, Nov 20, 2020 at 02:48:50PM +0800, Min Guo wrote: > > > > Hi greg k-h: > > > > On Wed, 2020-11-18 at 12:48 +0100, Greg Kroah-Hartman wrote: > > > > > On Tue, Nov 17, 2020 at 04:21:25PM +0800, min.guo@mediatek.com wrote: > > > > > > From: Min Guo > > > > > > > > > > > > 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 > > > > > > --- > > > > > > 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? > > > > > > > > I have tested this patch on Mediatek's platform, and not sure if it > > > > will affect other vendors' platforms. > > > > > > > > Dear Bin: > > > > > > > > Does this patch will affect other vendors' platforms? > > > > > > The hardware specs will answer this question, what do they say about > > > this read? > > > > Sorry, I didn't seen the comment on the hardware specs indicate that > > devctl register needs to read once to take effect. > > 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. Alan Stern