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 78194CD98DE for ; Tue, 16 Jun 2026 00:15:30 +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:Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Subject:Cc:To: From:Date:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=WzApdNind1Co5Xbcn1rQaSPzEq7He8P/6Dkl73QhY40=; b=mrvfRwyE1lJavQmxW/DM19rc3S wrLpCPtgYRSkVvphR0iiki1Atrzn09q4LgbYoklrSFVvPnGXS00jd++UsOmNXrdoBDp/pd8Ro0y6K gEjNukKx65o8is88YDP5Qzon8H9B2xSPn5WeSXsC2S3FZSAwXvIWsA47WbQ4AiGE4PTBJNJZ3ArLx TjrrYTPwMu3e4T+0bRAP4qSmOktamhdMN+66fb/8sH9uxs7OzswLc2/bVjuvMOFou6V5Z4P0xgGnR tiPpOSlNrI2+Q0YGsiiZCmStu3WVOa30BoAXmsWmNdAjX1tInbPORjg7SHRsioIfvwxgtGINAhQFK iZb32zlA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wZHSd-0000000EzsI-4AZ4; Tue, 16 Jun 2026 00:15:23 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wZHSd-0000000Ezs4-0NCd; Tue, 16 Jun 2026 00:15:23 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 9509A418E2; Tue, 16 Jun 2026 00:15:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6DC11F000E9; Tue, 16 Jun 2026 00:15:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781568922; bh=WzApdNind1Co5Xbcn1rQaSPzEq7He8P/6Dkl73QhY40=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=T+q5pju7LWkXd6Y1SVay308qFKHCSGXe8YQWAXzQQLRhoLNOLXzV1F73822ZYC85z IlLlAvhIYmnN2QcfASlc1yAUZBKFXbPxLRFkLNMQIP75jyeBK17y/t+KCYA92cfKLG EsciXIYoR4P/Eg+1zcRDmKU3MCSWZICwYbbZw7RXTy5UYG+RHOWq5Ar2qa0LOSCFdr hVM8Ensq68LbFj1dR0BQNVGO2Gw4mqnJAwZU84AxQ3b0Cae7bYWTqpkNcF6xO0aEqM 8tV3Ffsx2SGbMKO4SVbFHPsPUX4WSq/XHLwt1FSiQgs1nIeRVj08Z+NTxrMc6Hg3Lt giATJZ4GSttxQ== Date: Mon, 15 Jun 2026 17:15:21 -0700 From: Jakub Kicinski To: daniel@makrotopia.org Cc: chester.a.unal@arinc9.com, andrew@lunn.ch, olteanv@gmail.com, davem@davemloft.net, edumazet@google.com, pabeni@redhat.com, matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com, linux@armlinux.org.uk, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Subject: Re: [PATCH net-next v2 5/8] net: dsa: mt7530: replace mt7530_read with regmap_read Message-ID: <20260615171521.60d93bf1@kernel.org> In-Reply-To: <20260615235649.1060736-1-kuba@kernel.org> References: <20260615235649.1060736-1-kuba@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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 Mon, 15 Jun 2026 16:56:49 -0700 Jakub Kicinski wrote: > > static u32 > > -mt7530_read(struct mt7530_priv *priv, u32 reg) > > +mt7530_mii_poll(struct mt7530_dummy_poll *p) > > { > > - int ret; > > u32 val; > > > > - ret = regmap_read(priv->regmap, reg, &val); > > - if (ret) { > > - WARN_ON_ONCE(1); > > - dev_err(priv->dev, > > - "failed to read mt7530 register\n"); > > - return 0; > > - } > > + regmap_read(p->priv->regmap, p->reg, &val); > > > > return val; > > } > > [Medium] > The old wrapper guaranteed val == 0 on failure. The new mt7530_mii_poll() > declares val without an initializer and ignores the regmap_read() return > code, so on a failed underlying transfer val is whatever was on the stack. > > Looking at drivers/net/dsa/mt7530-mdio.c::mt7530_regmap_read(): > > ret = bus->write(bus, priv->mdiodev->addr, 0x1f, page); > if (ret < 0) > return ret; > > lo = bus->read(bus, priv->mdiodev->addr, r); > hi = bus->read(bus, priv->mdiodev->addr, 0x10); > > *val = (hi << 16) | (lo & 0xffff); This looks legit, AFAICT, sadly. Maybe just write *val = 0; in mt7530_regmap_read() unconditionally ?