From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-03.galae.net (smtpout-03.galae.net [185.246.85.4]) (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 65B3738D6A4; Wed, 25 Mar 2026 09:40:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.85.4 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774431626; cv=none; b=cbRLZJaImoKoSZv1Z+ISDJqA59PhF3nnAigCQ6NuPTXUY+tR3aaWlH60Klsn9Ba6UlOLgqEXc9baPfp8qCTzje6E84xj7YdcF+b9u9ou90aIwWEu9xRgJuyXmlSbdKc2xKwLhbgoFUnk4jSlfjUwbbH1wI4gB0Q7c7F5DYsQLDw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774431626; c=relaxed/simple; bh=ic4ovVVbngDbHXUn1s4sSFh/sIJ+WuTucWOFyOVbcJc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=ETyBSi1e13h+Y2QndeLg5lMMCDc56zVajmXbJmyBeWHRa+aqcmT5FgkLedN0T1a8Te+nQrYvrf6lB0GhTE6CWZSkzZNOxxu0zu9IUtg5YFC1MlBBUK/Q7lsmjIlebTKbTMFnD9y85TFhALFpp0Iq9bTNvweAIl0nWrJjQja6JQI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=SHoPhh5o; arc=none smtp.client-ip=185.246.85.4 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="SHoPhh5o" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-03.galae.net (Postfix) with ESMTPS id 858994E427E9; Wed, 25 Mar 2026 09:40:20 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 4CCBE601A1; Wed, 25 Mar 2026 09:40:20 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id E950A104513B2; Wed, 25 Mar 2026 10:40:14 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1774431619; h=from:subject:date:message-id:to:cc:mime-version:content-type: in-reply-to:references; bh=0ixsUbiwjr2cUCJBEr3rNQHAH9XP6hNBHzk2pZT9agY=; b=SHoPhh5ohLqKRFyhAtzIElxDGJCK3uhMK5h3vKQRUgiXWVtAGX9DX1SGCIhFfzM/klpmUP UIoSjK8c9VkbQPtoW23LBM1zpaaXPmf6+N581B0om6GuzHgoPiOEG+PQ3ANksPIHYjItTr qNBrbyfpFXhyplGPqXH2nDVBu2LvgMiP3zhsMpDAhivvpo88LfxODZWSgI1jNHzQaxp3pB p56CA3fy7Fe8YsXPpQfJrB6RdoulJwAVHjeoqKyo2RV/hjbCc7YgkiB5Q7DqNwhWUjaLQB 3mHB+g7ENoPmJSdYBJf5uvFk6eGrOcCEwWYwVI2ZqFvKEY8PDpZerf3nmlVV9Q== From: Romain Gantois To: "Russell King (Oracle)" Cc: Mark Brown , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Andrew Lunn , Heiner Kallweit , Liam Girdwood , Maxime Chevallier , Thomas Petazzoni , netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next 2/2] net: sfp: manage receiver and transmitter regulators Date: Wed, 25 Mar 2026 10:40:09 +0100 Message-ID: <5088970.31r3eYUQgx@fw-rgant> In-Reply-To: References: <20260303-sfp-regulators-v1-0-7101ae34cb84@bootlin.com> <6022954.DvuYhMxLoT@fw-rgant> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart4723872.LvFx2qVVIh"; micalg="pgp-sha512"; protocol="application/pgp-signature" X-Last-TLS-Session-Version: TLSv1.3 --nextPart4723872.LvFx2qVVIh Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8"; protected-headers="v1" From: Romain Gantois To: "Russell King (Oracle)" Date: Wed, 25 Mar 2026 10:40:09 +0100 Message-ID: <5088970.31r3eYUQgx@fw-rgant> In-Reply-To: MIME-Version: 1.0 On Friday, 20 March 2026 15:45:31 CET Russell King (Oracle) wrote: > On Fri, Mar 20, 2026 at 10:39:10AM +0100, Romain Gantois wrote: > > Originally, I implemented a runtime PM support in the SFP core. This > > allowed to cut power to the cages when the attached network interface was > > down, thereby saving power. > > Have you measured how much power is saved by this? Sure, here are a few measures of saved power with several different modules I've tested. The measures were done with a shunt resistor on the regulator line feeding all power pins on both SFP cages. Only one SFP cage was occupied during each measure and the upper network interface was down. Module | Power saved (uW) SFP-10G-T-I | 80 SFP-10G-T-30 | 359 SFP-GB-GE-T | 191 CHAMPION ONE 1000SFPT | 188 SFP-H10GB-CU1M | 0 ES8512-3LCD05 | 248 SFP100BFXST | 351 So with both SFP cages occupied, we could see about 0.7mW of saved power by cutting the regulators to the cages. Thanks, -- Romain Gantois, Bootlin Embedded Linux and Kernel engineering https://bootlin.com --nextPart4723872.LvFx2qVVIh Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part. 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