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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F1D00D1CDC6 for ; Tue, 9 Dec 2025 11:28:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=DwKdmCUbXETjxy9fokPP+UnDSthHBd6FAyICBa61gQE=; b=FbYAV5pQn2OhuUAsRBZ/KY85iY 09B6xTIPfnl7NohEIH7e9b9EKG3o1k33/tWjXUGeYEccxYNVtlmhDJ60ulgR+Pw4sKWivW6RXe7oP Su5ggqftXGgVJM0ygI028tB8gn5qzXRXWv4zeqyBpRQ/ZXZEcB8Fn7yChwvcrYampTGK7EIbihup9 EPgaqAxs+I+XHjJQkblTXPv4+SJYVZ0Xe4v8zwkoq8EAn50lSSM+xmll6SF5JBiK860IK/secyyAl rhnoABSMd2/4Km4H4mtKHgADDHfFRSUlUJ8+kmBq1qxsR2ux3QVjxyfID+Isg2ifZGEueFpp53pim 0IaBGujQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vSvtM-0000000EBVE-3CPG; Tue, 09 Dec 2025 11:28:28 +0000 Received: from pandora.armlinux.org.uk ([2001:4d48:ad52:32c8:5054:ff:fe00:142]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vSvtJ-0000000EBUl-3mEX for linux-arm-kernel@lists.infradead.org; Tue, 09 Dec 2025 11:28:27 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=armlinux.org.uk; s=pandora-2019; h=Sender:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding: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=DwKdmCUbXETjxy9fokPP+UnDSthHBd6FAyICBa61gQE=; b=D9rFHetJk7ay/DXTWcogtOMRUt jy1aVrj+NO6xKIk/M8evsvfydfIZJbYw5Ui+Ujn56/7VBa305YJ9I7tF7Rtd+9Yr1dniHavtI1T+J sWcFLnp2VymQ0Ze+CS0nFMDv67CRoP0GIL2q0izyU6yk6GwFYSXMqyF4PZKzrdEhZKKIL+fM1Tcmf uajhTlqMaBxi6tMsohBHsXEkWI+D7+HWVpXqc9TaX4mZpY71tyG6ualnvhbg9oEo2Vfl8NS4fcZdk 4zdhlgTxaqpZXtjYRbmfefhLWrvcEjUh+WsNaxL2SLa5xXbs3D7yZYrmRUqclUH7fNT8haY2vupJ6 GFS6nqQw==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:34968) by pandora.armlinux.org.uk with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1vSvsw-000000000Nz-0ADF; Tue, 09 Dec 2025 11:28:02 +0000 Received: from linux by shell.armlinux.org.uk with local (Exim 4.98.2) (envelope-from ) id 1vSvsr-000000005xz-34kQ; Tue, 09 Dec 2025 11:27:57 +0000 Date: Tue, 9 Dec 2025 11:27:57 +0000 From: "Russell King (Oracle)" To: Jacky Chou Cc: Andrew Lunn , Heiner Kallweit , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Joel Stanley , Andrew Jeffery , Potin Lai , netdev@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net v2] net: mdio: aspeed: add dummy read to avoid read-after-write issue Message-ID: References: <20251209-aspeed_mdio_add_dummy_read-v2-1-5f6061641989@aspeedtech.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20251209-aspeed_mdio_add_dummy_read-v2-1-5f6061641989@aspeedtech.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251209_032826_211122_C6C65032 X-CRM114-Status: GOOD ( 11.09 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Dec 09, 2025 at 07:15:31PM +0800, Jacky Chou wrote: > + /* Workaround for read-after-write issue. > + * The controller may return stale data if a read follows immediately > + * after a write. A dummy read forces the hardware to update its > + * internal state, ensuring that the next real read returns correct data. > + */ > + (void)ioread32(ctx->base + ASPEED_MDIO_CTRL); What purpose does this cast to void achieve in an already void context? We have plenty of functions that get called in the kernel that return a value which the caller ignores, never assigning to a variable, none of these warn. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!