From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from vps0.lunn.ch (vps0.lunn.ch [156.67.10.101]) (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 C3ED051615B; Wed, 23 Sep 2026 18:35:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=156.67.10.101 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790188565; cv=none; b=ds/vfYzGUo2nycK/npTY+LYoZ2WHzrHzrTcuHuOgb5WWS5nUYhQdJpJk5ZTDQrj5594f6otDChbIyoF8bIbYM7YwXDuIbrs3/KHgH0eiUyugSmI2qDlGaT4bAvrymf6GvnqiBJ3VAfwYdYjURPylxfAM7YEUGkN+LCfVlQ3bO2o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790188565; c=relaxed/simple; bh=q4HUdbYJbdNB46N8Hk+HNN2RCzv/8hW08osPcRdAG/o=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=JSSjMFto4Znz8rk67zEjWxhREemzRHmfLFV1ILk9yta+Ncf4LPF9cJ85by/Ci37QaJ/hXFY+sRSraGGVAH7/4weAJeVR7jgn6HH1r+2NbCZXzRrFjcvcN6YDAE63xslEupxVdNio5GMPNLtnQJBm5rN+ZNZHqFrikEVE7JeIRdA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lunn.ch; spf=pass smtp.mailfrom=lunn.ch; dkim=pass (1024-bit key) header.d=lunn.ch header.i=@lunn.ch header.b=iKAwokD+; arc=none smtp.client-ip=156.67.10.101 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lunn.ch Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lunn.ch Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=lunn.ch header.i=@lunn.ch header.b="iKAwokD+" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lunn.ch; s=20171124; h=In-Reply-To:Content-Disposition:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:From:Sender:Reply-To:Subject: Date:Message-ID:To:Cc:MIME-Version:Content-Type:Content-Transfer-Encoding: Content-ID:Content-Description:Content-Disposition:In-Reply-To:References; bh=HXJnRJRTxgy4hjZ9q9bU+112uVIymJuRU1zRdHwHYCA=; b=iKAwokD+QZzNxHtib6CZO8slHG 6a9ePUyZsbIPtW4/T3Hab0cy186YRSmwntzxMx+VRURlU6Th6lfT0b1Edbcu5hCNQ8o5Pr7O1g/fL YVecv794yM7XumvEu6aApqdRlWO1ZAkKj9lIr256PTNsIDLQDqJgD6ow4XnRUe3XWAeI=; Received: from andrew by vps0.lunn.ch with local (Exim 4.94.2) (envelope-from ) id 1x9Rod-006r79-Tp; Wed, 23 Sep 2026 20:35:35 +0200 Date: Wed, 23 Sep 2026 20:35:35 +0200 From: Andrew Lunn To: Coia Prant Cc: Mohd Ayaan Anwar , Maxime Chevallier , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Serge Semin , Heiner Kallweit , Russell King , Richard Cochran , Bjorn Andersson , Konrad Dybcio , Alexandre Torgue , Giuseppe Cavallaro , Jose Abreu , Maxime Coquelin , Jan Petrous , "Jose.Abreu@synopsys.com" , netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, Lorenzo Bianconi , Shawn Guo , Zhangfei Gao , Jitendra Vegiraju Subject: Re: [PATCH RFC net-next 0/9] net: introduce Qualcomm XPCS support and add Nord Ethernet plumbing Message-ID: References: <20260923-qcom_xpcs_nord_emac-v1-0-4b1c682af70f@oss.qualcomm.com> <5135e15d-b6ac-476c-9a7d-b7d64e4eed5c@bootlin.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: > Non-existent MMDs > ----------------- > Returning 0xffff on reads and silently discarding writes is what a > floating bus / unimplemented feature looks like, so I agree with that > direction. My pcs-xpcs-rk does the same. Did you read 802.3? 45.2: If a device supports the MDIO interface it shall respond to all possible register addresses for the device and return a value of zero for undefined and unsupported registers. Writes to undefined registers and read-only registers shall have no effect. The operation of an MMD shall not be affected by writes to reserved and unsupported register bits, and such register bits shall return a value of zero when read. This is what i was commenting about in my review, returning EOPNOTSUPP is not correct according to the standard. Andrew