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=-5.1 required=3.0 tests=BAYES_00,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 33158C47088 for ; Wed, 26 May 2021 15:42:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 12AF7613D7 for ; Wed, 26 May 2021 15:42:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234719AbhEZPnx (ORCPT ); Wed, 26 May 2021 11:43:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50256 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232537AbhEZPnx (ORCPT ); Wed, 26 May 2021 11:43:53 -0400 Received: from pandora.armlinux.org.uk (pandora.armlinux.org.uk [IPv6:2001:4d48:ad52:32c8:5054:ff:fe00:142]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9348AC061574 for ; Wed, 26 May 2021 08:42:21 -0700 (PDT) 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=q70he09otM5/1Xz5tUyVV1uZT8HE8Hw6OEhIzMGEJKM=; b=A0bvdv7hiCQrh0jCh9pwOWog4 0XdpFdT8Pz3TnALgswbJGWB4sUYyNXSFkZee4Wqo6Wv2+KS9Dz0n+9jji5yjD3tjKkC8bumRa8Q6b CMkfUE91CyO4q6dGfKHTpl5f5tMBQaAno2VOZvZTkfrOAG/S0jmfXjdISN4wf4OWomTOGJslxvKRQ KK1j5I+X1HZq4os+1D5JDKJo3OdYushdFA8EYFKOktVSNNpiHNpbwE/pe3fmK2JTBxxnv8lbKdhMx NXQjNjBZFaHFM6Bvaw7voE8zcvuY0S1T/veBMA5ksj4zQJ8mI5UIinPsAdEEX6xMAR6ml+0i568Rl VPzsaRcKw==; Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:44382) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1llvfn-0005sD-6a; Wed, 26 May 2021 16:42:19 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1llvfm-0002wK-OE; Wed, 26 May 2021 16:42:18 +0100 Date: Wed, 26 May 2021 16:42:18 +0100 From: "Russell King (Oracle)" To: Vladimir Oltean Cc: Jakub Kicinski , "David S. Miller" , netdev@vger.kernel.org, Florian Fainelli , Andrew Lunn , Vivien Didelot , Heiner Kallweit Subject: Re: [RFC PATCH v2 linux-next 03/14] net: dsa: sja1105: the 0x1F0000 SGMII "base address" is actually MDIO_MMD_VEND2 Message-ID: <20210526154218.GI30436@shell.armlinux.org.uk> References: <20210526135535.2515123-1-vladimir.oltean@nxp.com> <20210526135535.2515123-4-vladimir.oltean@nxp.com> <20210526152454.GG30436@shell.armlinux.org.uk> <20210526153447.yjgbj5uhxxnvxvbs@skbuf> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210526153447.yjgbj5uhxxnvxvbs@skbuf> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: Russell King (Oracle) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, May 26, 2021 at 06:34:47PM +0300, Vladimir Oltean wrote: > Hi Russell, > > On Wed, May 26, 2021 at 04:24:54PM +0100, Russell King (Oracle) wrote: > > On Wed, May 26, 2021 at 04:55:24PM +0300, Vladimir Oltean wrote: > > > - const struct sja1105_regs *regs = priv->info->regs; > > > + u64 addr = (mmd << 16) | pcs_reg; > > > > What is the reason for using "u64" here. pcs_reg is 16-bits, and mmd is > > five bits, which is well below 32 bits. So, why not u32? > > The "addr" variable holds a SPI address, and in the sja1105 driver, the > SPI addresses are universally held in u64 variables, mainly because of > the packing() API (Documentation/core-api/packing.rst). As you are passing it into a function, the argument of which is a u64, the compiler will promote the u32 to a u64 by itself. I guess it doesn't actually matter, but the current code just looks really weird. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!