From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2DA671B85F8; Fri, 24 Oct 2025 01:10:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761268215; cv=none; b=qUlHc0M4ww3c+tSwez8KaVwMTZXD6GDboAqKhl46W44ytWmAN9FW0/ziQuGUHxAQa1sb2muqiPk1nFpUcgypeZodfNj/hbHNoUtC7R7LO5xyGowV5MjCv2SaWi/Q/V9omRSDA31ZB0cGlVg+3G0zgn3r8Yry22xIT/n9SxizT3I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761268215; c=relaxed/simple; bh=OLXoSnqBAFgBwoQMFtvAMOPLw94jaNvTQASIeLyNyII=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=VEox005NoE9Nm3+x4Znm/nBy0mxit5DaXd1O+9m60qbU+Xt4gi6ncWp5Iam51wcpPZYiZ5Bz9AxNfC5dNCIktNui4FC+PXRJdb0FAAeyIrXdofdJ1r2NP2fUBrHurl42BbgXtUTzCgW1GlZeERTyakr8uCKFT1e6HvY952vW0hg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WrKHmuPa; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="WrKHmuPa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B8DAEC113D0; Fri, 24 Oct 2025 01:10:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1761268214; bh=OLXoSnqBAFgBwoQMFtvAMOPLw94jaNvTQASIeLyNyII=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=WrKHmuPagZflA2cQbaM+uEDIZWz7+utTLmFSlMSAPNEEw+e+E1yQnm0YZ+3sskOqS qEtXImiN9VvvlIjlo6qCtvWgut2rDBAnCNhkTPNb93e7uoiU0Vvyyz4aon7zGDm/d9 35g9lMWnqGFAW1mHhfkRQnVIYBEjU7KxUu5F405kPF3ShnXDxdmGqlL57HFnOPLSht z3Doxp2nBxo9ElMu2bt2yFm4xMyuqsEV+WG8LAk5nDoE3464Ym6qR9jlfKMl7Nexze bQtKShADtwAyzv5zY1mV3J59MgzusTVAH2ses4qh3Zl8oYa2eGPWDt+G/GeR1zKC1U PjZ9K9aEWyIvg== Date: Thu, 23 Oct 2025 18:10:12 -0700 From: Jakub Kicinski To: Oleksij Rempel Cc: Andrew Lunn , "David S. Miller" , Eric Dumazet , Paolo Abeni , Simon Horman , Donald Hunter , Jonathan Corbet , Heiner Kallweit , Russell King , Kory Maincent , Maxime Chevallier , Nishanth Menon , kernel@pengutronix.de, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, UNGLinuxDriver@microchip.com, linux-doc@vger.kernel.org, Michal Kubecek , Roan van Dijk Subject: Re: [PATCH net-next v7 3/5] ethtool: netlink: add lightweight MSE reporting to LINKSTATE_GET Message-ID: <20251023181012.6bf107a6@kernel.org> In-Reply-To: <20251020103147.2626645-4-o.rempel@pengutronix.de> References: <20251020103147.2626645-1-o.rempel@pengutronix.de> <20251020103147.2626645-4-o.rempel@pengutronix.de> Precedence: bulk X-Mailing-List: linux-doc@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, 20 Oct 2025 12:31:45 +0200 Oleksij Rempel wrote: > Extend ETHTOOL_MSG_LINKSTATE_GET to optionally return a simplified > Mean Square Error (MSE) reading alongside existing link status fields. > > The new attributes are: > - ETHTOOL_A_LINKSTATE_MSE_VALUE: current average MSE value > - ETHTOOL_A_LINKSTATE_MSE_MAX: scale limit for the reported value > - ETHTOOL_A_LINKSTATE_MSE_CHANNEL: source channel selector > > This path reuses the PHY MSE core API (struct phy_mse_capability and > struct phy_mse_snapshot), but only retrieves a single value intended for > quick link-health checks: > * If the PHY supports a WORST channel selector, report its current > average MSE. > * Otherwise, if LINK-wide measurements are supported, report those. > * If neither is available, omit the attributes. > > Unlike the full MSE_GET interface, LINKSTATE_GET does not expose > per-channel or peak/worst-peak values and incurs minimal overhead. > Drivers that implement get_mse_capability() / get_mse_snapshot() will > automatically populate this data. > > The intent is to provide tooling with a "fast path" health indicator > without issuing a separate MSE_GET request, though the long-term overlap > with the full interface may need reevaluation. I don't think this justification is sufficient, we don't normally duplicate information in uAPI to make user space have to issue fewer calls. ethtool $link already issues a number of calls to the kernel.