From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1aOKV9-0007Fi-Km for barebox@lists.infradead.org; Wed, 27 Jan 2016 07:26:53 +0000 Date: Wed, 27 Jan 2016 08:26:29 +0100 From: Sascha Hauer Message-ID: <20160127072629.GG13058@pengutronix.de> References: <1453787758-12688-1-git-send-email-andrew.smirnov@gmail.com> <1453787758-12688-7-git-send-email-andrew.smirnov@gmail.com> <20160126215555.GD13058@pengutronix.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "barebox" Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: [PATCH 7/7] commands: Add mdio_read and mdio_write To: Andrey Smirnov Cc: "barebox@lists.infradead.org" On Tue, Jan 26, 2016 at 06:09:00PM -0800, Andrey Smirnov wrote: > On Tue, Jan 26, 2016 at 1:55 PM, Sascha Hauer wrote: > > On Mon, Jan 25, 2016 at 09:55:58PM -0800, Andrey Smirnov wrote: > >> Add commands for low-level access to MDIO bus. > > > > Do we really need this? We can already read/write phy registers using > > /dev/phyx which imo is quite convenient since it can be accessed with > > regular md/mw commands. > > > > This of course is currently limited to the phys that are actually > > registered, you can't just bang on MDIO addresses on which no phys are > > registered. Maybe we could register all phys on a MDIO bus instead of > > only the used ones? > > Just to explain the purpose of this patch -- there are number of > reasons we might want to be able to access "unregistered" PHYs: > > - Not all MDIO attached devices would have PHYSID1,2 registers > available which might cause mdiobus_scan() to not detect those PHYs > > - MDIO bus troubleshooting > > As for registering all PHYs on a bus, correct me if I am wrong but > that would result in 32*N number of entries in /dev, where N is number > of MDIO buses in the system. The device I am working with right now > has 3 MDIO buses which would mean that I'd end up with 96 additional > entries in /dev, which might be a little bit overwhelming from UI > point of view. The other UI problem with that approach is that > /dev/phy's are numbered linearly so in order to figure out how to > access device on bus N at address M, user would have to perform N*32 + > M in their head. We could register the phys with name like: "mdio%d-phy%02x", dev->bus->dev.id, mdev->addr That would make it clear which phy belongs to which bus. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox