From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout-04.galae.net (smtpout-04.galae.net [185.171.202.116]) (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 0DBB2492501 for ; Tue, 3 Mar 2026 15:55:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.171.202.116 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772553311; cv=none; b=MflEfKLvMd3tQsGO88mNlO5WGC4ombVIFB5VJWVsP+VFBKLIe4EEdCrP9MdDvCfqe8GCDqTvsVw9K9v1OD3kTzj4htg+cJ63TJkm7B9xd3X5LJl4k5FGHmK6S0HVKBxBV2knKbzhd980LZmjMu3ScIx2wE+QVaPQcwaBW5IoCtw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772553311; c=relaxed/simple; bh=7b8F1HaCkpN6fayVr7HNxwpvh017ORH7b3smsXK8+0s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=CkhA9iZo32Qztb+2KRIOFHFTMVa5PMADxdwtBlPEswM3f6s/OV3m4lcYwjLV4OQjaWRdFexvj/opoguxY9aKqNbbwtcWdwOM8huCvHsXbB/e/ah8kOTzS4f5jsBhFE4gawPuoRCXkXT/Tdr7rbzc1Zj4kdKsVgEi5rCG/94LTh8= 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=woXOvWDl; arc=none smtp.client-ip=185.171.202.116 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="woXOvWDl" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-04.galae.net (Postfix) with ESMTPS id EAF35C40FAF; Tue, 3 Mar 2026 15:55:23 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 374305FF29; Tue, 3 Mar 2026 15:55:06 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 823341036915A; Tue, 3 Mar 2026 16:55:01 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1772553305; h=from:subject:date:message-id:to:cc:mime-version:content-type: in-reply-to:references; bh=SH5CVKmEIbnVEu71258fPU3XMEnF0AcPei/4hXDNKko=; b=woXOvWDlKUBjnhuOi/e1OGikcft5vpeuygIsCNkvN1tsXPHf+Lfw/KgOnxveeki9Eoiyb9 AKMH/InS9g+yX9oOEPzwV+iZWv2+NVAB+FExPvuoeksDdqIEqHIAokikSvLaT2qkqBWI4D TvQDeB/UcsKVIUwxnNTS6a9/NznBF30sGWDzhUm3WANLH/3QnC9h884Wg3frFDjVdiG1w6 98MCuCeIkV8BJGqMcNSU/JfqPdDON0XhQq784puj/8x0f6f0KH3bVBPPrhAu06qMpOVayp YohGh713fBhUAj//3xNE4WCBimRQsQOpJUG5kp8gcNl7ZGVOdQsTKXD/35xdTA== From: Romain Gantois To: "Russell King (Oracle)" Cc: Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Andrew Lunn , Heiner Kallweit , Liam Girdwood , Mark Brown , Maxime Chevallier , Thomas Petazzoni , netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net-next 0/2] net: sfp: Describe and handle regulators Date: Tue, 03 Mar 2026 16:54:56 +0100 Message-ID: <9586950.CDJkKcVGEf@fw-rgant> In-Reply-To: References: <20260303-sfp-regulators-v1-0-7101ae34cb84@bootlin.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart3331196.5fSG56mABF"; micalg="pgp-sha512"; protocol="application/pgp-signature" X-Last-TLS-Session-Version: TLSv1.3 --nextPart3331196.5fSG56mABF Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8"; protected-headers="v1" From: Romain Gantois To: "Russell King (Oracle)" Date: Tue, 03 Mar 2026 16:54:56 +0100 Message-ID: <9586950.CDJkKcVGEf@fw-rgant> In-Reply-To: MIME-Version: 1.0 Hi Russell, On Tuesday, 3 March 2026 16:10:12 CET Russell King (Oracle) wrote: > On Tue, Mar 03, 2026 at 02:54:25PM +0100, Romain Gantois wrote: > > Hi everyone, > > > > This series describes regulators supplying the VccT and VccR pins of an > > SFP > > cage or soldered-down transceiver. > > > > These regulators can then be turned on only when the SFP device is probed, > > thus saving power on systems which only load SFP cage support at certain > > times, or load SFP device descriptions via device tree overlays. > > > > Please let me know what you think. > > As ever, I don't want to be adding support for stuff into mainline > which doesn't ever get used - historically, we've had a lot of that. > So, any patch set which adds some kind of facility like this needs to > be accompanied by a user of it. > I understand, though I'm dealing with an out-of-tree board but I understand that this doesn't really count as a valid first use case. > This is especially true in this case, because I want to see why you're > wanting to have two regulators, when INF-8074 suggests that both VccT > and VccR should be derived from the same supply. The reason the > modules have separate supplies for the transmitter and receiver is > because the host side has the supply filtering networks to ensure > cross-talk between each is kept to a minimum. Interesting, I wasn't aware of this. I thought it was something like "being able to shut down the transmitter side only while waiting for a WoL packet". It seems like there won't be a v2 anyway but I just wanted to explain why I went with two regulators in the first place. Thanks, -- Romain Gantois, Bootlin Embedded Linux and Kernel engineering https://bootlin.com --nextPart3331196.5fSG56mABF Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part. 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