From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from yx-out-2324.google.com (yx-out-2324.google.com [74.125.44.30]) by ozlabs.org (Postfix) with ESMTP id 24A0ADDFC7 for ; Fri, 1 May 2009 01:11:46 +1000 (EST) Received: by yx-out-2324.google.com with SMTP id 8so1036958yxb.39 for ; Thu, 30 Apr 2009 08:11:44 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <625fc13d0904200529l152b8d75g33c3f940de1b2920@mail.gmail.com> <1240388476.17445.10.camel@pasglop> From: Grant Likely Date: Thu, 30 Apr 2009 09:11:24 -0600 Message-ID: Subject: Re: Porting the ibm_newemac driver to use phylib (and other PHY/MAC questions) To: Kyle Moffett Content-Type: text/plain; charset=ISO-8859-1 Cc: linuxppc-dev@ozlabs.org, "Linux-Kernel@Vger. Kernel. Org" , netdev List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, Apr 30, 2009 at 9:04 AM, Kyle Moffett wrote: > On Wed, Apr 22, 2009 at 4:21 AM, Benjamin Herrenschmidt > wrote: >> On Mon, 2009-04-20 at 20:10 -0400, Kyle Moffett wrote: >>> > IIRC, Ben had some issues with how phylib and the EMAC would need to >>> > interact. =A0Not sure if he has those written down somewhere or not. >>> > (CC'd). >>> >>> Hmm, yeah, I'd be interested to see those. =A0There's enough similar >>> between phylib and the EMAC and sungem drivers that I'm considering a >>> series of somewhat-mechanical patches to make EMAC and sungem use the >>> "struct phy_device" and "struct mii_bus" from phylib, possibly >>> abstracting out some helper functions along the way. >> >> Yup, emac and sungem predate phylib. >> >> I had a quick look at what it would take to port at least emac over, the >> main issue was that I want to be able to sleep (ie, take a mutex) in my >> mdio read/write functions, and back then, phylib wouldn't let me do that >> due to spinlock and timer/softirq usage. > > Ok, I've made some progress in the port, but right now I'm trying to > puzzle out what the "gpcs" bits in the code are. =A0From the few > publicly available docs and some mailing list posts, the gpcs address > appears to be some kind of integrated virtual PHY used when 460GT-ish > chips are communicating via an SGMII bus. =A0My current plan of action > is to separate the "gpcs" out into a separate PHY device controlled by > the emac code. > > I'm also curious about the intent of the "mdio_instance" pointer (IE: > the "mdio-device" property). =A0Is that used when all the PHY devices > are attached to the MDIO bus of only one of the (multiple) emac > devices? =A0Or is that for when two emac chipsets are connected to the > same MDIO bus wire? =A0(or both?) =A0What keeps the emac_instance pointed > to by the "mdio_instance" from going away while the other emac chipset > is using it? > > In either case, I plan to have the device actually holding the MDIO > bus run the mdiobus_alloc() and mdiobus_register() functions, then the > other emac instance will simply take a reference to that MDIO bus > (which would also pin down the emac instance that owns it). Just a heads up Kyle; there are changes queued in the netdev tree which add OF helpers for MDIO bus drivers and MAC drivers. See here: http://git.kernel.org/?p=3Dlinux/kernel/git/davem/net-next-2.6.git;a=3Dcomm= it;h=3D8bc487d150b939e69830c39322df4ee486efe381 and here is an example of a driver change: http://git.kernel.org/?p=3Dlinux/kernel/git/davem/net-next-2.6.git;a=3Dcomm= it;h=3D1dd2d06c0459a2f1bffc56765e3cc57427818867 Cheers, g. --=20 Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd.