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[23.128.96.18]) by mx.google.com with ESMTP id ga10si1361444ejc.686.2020.11.20.01.22.01; Fri, 20 Nov 2020 01:22:24 -0800 (PST) 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; Authentication-Results: mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b="XNqG64/n"; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727767AbgKTJUa (ORCPT + 99 others); Fri, 20 Nov 2020 04:20:30 -0500 Received: from mail.kernel.org ([198.145.29.99]:40102 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727757AbgKTJU1 (ORCPT ); Fri, 20 Nov 2020 04:20:27 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E803922264; Fri, 20 Nov 2020 09:20:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1605864026; bh=2u/5mhCZv1xdPFL6xL5rON8rEuNwDZ5NL6N7lPUewns=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XNqG64/n8KmjuhcLmgLYf48IecH4L16ozQdP/cgWyMIffoCtf5iL0LH+I73HgmXNg AqlemRpN+JQttIotgWDRxHQTUti6HwOpzRC+nLmEOqs0zr05ylBp/WNzt+TmLSEls+ z1Ti3DfpbibbsXvK+UXsqXlDwyD6HKA58gHvntmM= Date: Fri, 20 Nov 2020 10:20:58 +0100 From: Greg Kroah-Hartman To: Min Guo Cc: 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: References: <20201117082125.7619-1-min.guo@mediatek.com> <1605854930.3995.8.camel@mhfsdcap03> <1605858126.3995.14.camel@mhfsdcap03> <1605862935.3995.20.camel@mhfsdcap03> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1605862935.3995.20.camel@mhfsdcap03> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 20, 2020 at 05:02:15PM +0800, Min Guo wrote: > On Fri, 2020-11-20 at 09:36 +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? > > Sorry for confused you, I searched the hardware specs, but did not find > the special description of the register devctl indicating that it needs > to be read out before the hardware can work. If this is a PCI device, that is implied as that is how all PCI devices work, right? What is the problem that is fixed by removing this read? thanks, greg k-h