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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 5B8ABC32767 for ; Fri, 3 Jan 2020 17:53:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3298820866 for ; Fri, 3 Jan 2020 17:53:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=lunn.ch header.i=@lunn.ch header.b="QUTR2W8s" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728242AbgACRxe (ORCPT ); Fri, 3 Jan 2020 12:53:34 -0500 Received: from vps0.lunn.ch ([185.16.172.187]:46780 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728110AbgACRxe (ORCPT ); Fri, 3 Jan 2020 12:53:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lunn.ch; s=20171124; h=In-Reply-To:Content-Transfer-Encoding:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=Ik53vLhmD+EUsy1sL+CsKQR1KxqBKtMb4tA7fcFpO+w=; b=QUTR2W8shqqZiTDH2jgUPvAyHw tZDvbAED4kSORlvuj56UaZa28Xq4KqVKnjVKFotuoyHj+QwgouApJqIQUfCTRAPXp3bFQkQFCHLM9 JkmGINPf/mEnk1l+HdspUGPlOJhPnZ5QGYlbT0mgfT7pfSKAoUPiqVuXwLDdPm9Lan0A=; Received: from andrew by vps0.lunn.ch with local (Exim 4.93) (envelope-from ) id 1inR8Q-0000zy-9G; Fri, 03 Jan 2020 18:53:18 +0100 Date: Fri, 3 Jan 2020 18:53:18 +0100 From: Andrew Lunn To: Matthew Wilcox Cc: yu kuai , klassert@kernel.org, davem@davemloft.net, hkallweit1@gmail.com, jakub.kicinski@netronome.com, hslester96@gmail.com, mst@redhat.com, yang.wei9@zte.com.cn, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, zhengbin13@huawei.com Subject: Re: [PATCH] net: 3com: 3c59x: remove set but not used variable 'mii_reg1' Message-ID: <20200103175318.GN1397@lunn.ch> References: <20200103121907.5769-1-yukuai3@huawei.com> <20200103144623.GI6788@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200103144623.GI6788@bombadil.infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Jan 03, 2020 at 06:46:23AM -0800, Matthew Wilcox wrote: > On Fri, Jan 03, 2020 at 08:19:07PM +0800, yu kuai wrote: > > Fixes gcc '-Wunused-but-set-variable' warning: > > > > drivers/net/ethernet/3com/3c59x.c: In function ‘vortex_up’: > > drivers/net/ethernet/3com/3c59x.c:1551:9: warning: variable > > ‘mii_reg1’ set but not used [-Wunused-but-set-variable] > > > > It is never used, and so can be removed. > ... > > if (dev->if_port == XCVR_MII || dev->if_port == XCVR_NWAY) { > > - mii_reg1 = mdio_read(dev, vp->phys[0], MII_BMSR); > > mii_reg5 = mdio_read(dev, vp->phys[0], MII_LPA); > > I know nothing about the MII interface, but in general this is not > a safe thing to do. Hi Matthew I fully agree about the general case. However, reading the MII_BMSR should not have any side affects. It would be an odd Ethernet PHY if it did. But I am curious why this read is here. There is a slim change the MDIO bus is broken, and this is a workaround. So it would be good if somebody dug into the history and found out when this read was added and if there are any comments about why it is there. Or if the usage of mii_reg1 as been removed at some point, and the read was not cleaned up. Andrew