From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-ig0-x241.google.com ([2607:f8b0:4001:c05::241]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1aOFXt-0005Sw-P5 for barebox@lists.infradead.org; Wed, 27 Jan 2016 02:09:22 +0000 Received: by mail-ig0-x241.google.com with SMTP id ik10so235299igb.1 for ; Tue, 26 Jan 2016 18:09:01 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20160126215555.GD13058@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> Date: Tue, 26 Jan 2016 18:09:00 -0800 Message-ID: From: Andrey Smirnov 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: Sascha Hauer Cc: "barebox@lists.infradead.org" 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. Andrey _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox