From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E589B19D07A; Tue, 16 Jun 2026 00:15:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781568923; cv=none; b=QSgQGtPY5QjO/bAfMufLPev84rllEkAP/6ocKToJZFySIzPwo4pN59jlCBJlemYFhtTNuO18So9OoKb4jxIhzbuvcM5hAy5OdD/mJhtK6reD142vN/K20NqtoEc77Zlxm5GY/UMXZ6iHIfzrKTZRV9qr2a3yxD8LeLSMTZAJaFE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781568923; c=relaxed/simple; bh=nAJovhwBTVkTiFEcITJJg8ZhgJaJExeRuwFj8cl0msA=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=V4FlrRIOealJM7h24+hf+sbuBbgHtam2cX4DkRvb8nRvUSK4iHrUQQn0dFIrHAjCkuhkqhwKvCJX1juSMTEGZMTleuN2cR5dlnqpvPC+l/NWeRenk3foyLsOccqRhrLBWlL3LXPL/MGBataQTNvo7AOqVLXNl9eHcQO3ef59z50= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=T+q5pju7; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="T+q5pju7" 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit 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 ?