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 67B0FC9830E for ; Wed, 23 Sep 2026 18:36:07 +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=HXJnRJRTxgy4hjZ9q9bU+112uVIymJuRU1zRdHwHYCA=; b=QhdNMO3U8LPQ8k38bOD5pYTewc MHCRzlFeTqIwSmcrjlzbCLbK/06q6UO78LMPvJRXfaJoTwAVvgak9MpG7Y9xW1et2f2ZL0S0f8JOb ZwAvSYGhXdsTM0sHSJZfkt8lvR1qqg2M6YuEatxyjPwhKDl24FpI7pG+znvPwcgFy8aWyeyFc5adY Yf1arj+KMqV4zeVr7PZM0Rx2V6mWh2gDm+M+7PeX7uCGE3mAuAkXTdYFqlIs3Qz3p573f4VJaC0A+ 8Zk0H+cSKpfwlzzeaL5LXLoHTVdtdyyT89hdiWY6cRbM5SVjldDbDYuzHH2MkHPVSti1H1Q+2UgQs absLTEPA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x9Rp2-00000009DWm-3tFX; Wed, 23 Sep 2026 18:36:00 +0000 Received: from vps0.lunn.ch ([156.67.10.101]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x9Roz-00000009DUo-1eCP for linux-arm-kernel@lists.infradead.org; Wed, 23 Sep 2026 18:35:59 +0000 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260923_113557_441011_2C4F8DB6 X-CRM114-Status: UNSURE ( 9.76 ) X-CRM114-Notice: Please train this message. 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 > 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