From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752106AbeEQNEM (ORCPT ); Thu, 17 May 2018 09:04:12 -0400 Received: from vps0.lunn.ch ([185.16.172.187]:34515 "EHLO vps0.lunn.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751280AbeEQNEK (ORCPT ); Thu, 17 May 2018 09:04:10 -0400 Date: Thu, 17 May 2018 15:04:06 +0200 From: Andrew Lunn To: Antoine Tenart Cc: davem@davemloft.net, linux@armlinux.org.uk, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, thomas.petazzoni@bootlin.com, maxime.chevallier@bootlin.com, gregory.clement@bootlin.com, miquel.raynal@bootlin.com, nadavh@marvell.com, stefanc@marvell.com, ymarkman@marvell.com, mw@semihalf.com Subject: Re: [PATCH net-next 1/2] net: phy: sfp: make the i2c-bus property really optional Message-ID: <20180517130406.GH8547@lunn.ch> References: <20180517082907.14420-1-antoine.tenart@bootlin.com> <20180517082907.14420-2-antoine.tenart@bootlin.com> <20180517124127.GG8547@lunn.ch> <20180517125648.GM32746@kwain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180517125648.GM32746@kwain> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 17, 2018 at 02:56:48PM +0200, Antoine Tenart wrote: > Hi Andrew, > > On Thu, May 17, 2018 at 02:41:28PM +0200, Andrew Lunn wrote: > > On Thu, May 17, 2018 at 10:29:06AM +0200, Antoine Tenart wrote: > > > The SFF,SFP documentation is clear about making all the DT properties, > > > with the exception of the compatible, optional. In practice this is not > > > the case and without an i2c-bus property provided the SFP code will > > > throw NULL pointer exceptions. > > > > > > This patch is an attempt to fix this. > > > > How usable is an SFF/SFP module without access to the i2c EEPROM? I > > guess this comes down to link speed. Can it be manually configured? > > > > I'm just wondering if we want to make this mandatory? Fail the probe > > if it is not listed? > > Yes, the other option would be to fail when probing a cage missing the > i2c description. I'd say a passive module can work without the i2c > EEPROM accessible as it does not need to be configured. I don't know > what would happen with active ones. Hi Antoine I was thinking about how it reads the bit rate from the EEPROM. From that it determines what mode the MAC could use, 1000-Base-X, 2500-Base-X, etc. Can you still configure this correctly via ethtool, if you don't have the bitrate information? Andrew