From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="Lhf3Nu8+" Received: from relay4-d.mail.gandi.net (relay4-d.mail.gandi.net [217.70.183.196]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3D759C9; Wed, 13 Dec 2023 09:12:51 -0800 (PST) Received: by mail.gandi.net (Postfix) with ESMTPSA id EBFDBE0003; Wed, 13 Dec 2023 17:12:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1702487569; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Y5TlHmWEUPrLvS1FVi0orOnaoJ8WBQaxRvgSpwfpfbE=; b=Lhf3Nu8+GyNG3qgU43seuI/4CVmSA5PeGwqa1jMFEbOrcCXwsFnlKeBN8+OL9LJ100v/i9 s6PWl1NWck+TkngarDqAkX7KQhn/C5kgpcviDmN9v4DoF8ZIJAx0FiCzeGqI+oL8tk/t/W iIGq+MuAZqjkfEFXhVl0KzJs6+Dbxr/jrtfGV+P+o55kyhhIZE4Dc4jlNag819/GuOEKzP JXHH/7KmfsbJPpPG5U6/OyLIsQMYrc/EBlay4BQ30kUH8h+3lO5XJzSwn0E1lBUNe93pXC 44y0wKlB5e2vIPAYTkKRhaP0INVRgM505IfJdC8OnVuZWi1NO1fSYLGWwHnzBA== Date: Wed, 13 Dec 2023 18:12:41 +0100 From: Maxime Chevallier To: "Russell King (Oracle)" Cc: Andrew Lunn , Daniel Golle , Heiner Kallweit , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net] net: phy: skip LED triggers on PHYs on SFP modules Message-ID: <20231213181241.6a5e8afd@device-28.home> In-Reply-To: References: <102a9dce38bdf00215735d04cd4704458273ad9c.1702339354.git.daniel@makrotopia.org> <20231212153512.67a7a35b@device.home> Organization: Bootlin X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; x86_64-redhat-linux-gnu) 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-Transfer-Encoding: 7bit X-GND-Sasl: maxime.chevallier@bootlin.com Hi Andrew, Russell, On Wed, 13 Dec 2023 15:27:28 +0000 "Russell King (Oracle)" wrote: > On Wed, Dec 13, 2023 at 10:08:25AM +0100, Andrew Lunn wrote: > > On Tue, Dec 12, 2023 at 03:35:12PM +0100, Maxime Chevallier wrote: > > > Hi Daniel > > > > > > On Tue, 12 Dec 2023 00:05:35 +0000 > > > Daniel Golle wrote: > > > > > > > Calling led_trigger_register() when attaching a PHY located on an SFP > > > > module potentially (and practically) leads into a deadlock. > > > > Fix this by not calling led_trigger_register() for PHYs localted on SFP > > > > modules as such modules actually never got any LEDs. > > > > > > While I don't have a fix for this issue, I think your justification > > > isn't good. This isn't about having LEDs on the module or not, but > > > rather the PHY triggering LED events for LEDS that can be located > > > somewhere else on the system (like the front pannel of a switch). > > > > SFP LEDs are very unlikely to be on the front panel, since there is no > > such pins on the SFP cage. > > > > Russell, in your collection of SFPs do you have any with LEDs? > > No, and we should _not_ mess around with the "LED" configuration on > PHYs on SFPs. It's possible that the LED output is wired to the LOS > pin on the module, and messing around with the configuration of that > would be asking for trouble. > > In any case, I thought we didn't drive the LED configuration on PHYs > where the LED configuration isn't described by firmware - and as the > PHY on SFP modules would never be described by firmware, hooking > such a PHY up to the LED framework sounds like a waste of resources > to me. > So it looks to me that the Daniel's patch does make sense then, even without considering the underlying locking issue ? Sorry for my misunderstanding of the LED driving that started this discussion :/ Maxime