From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from yw-out-2324.google.com (yw-out-2324.google.com [74.125.46.28]) by ozlabs.org (Postfix) with ESMTP id 5D3E2DE0F0 for ; Sat, 16 May 2009 00:52:41 +1000 (EST) Received: by yw-out-2324.google.com with SMTP id 2so1018225ywt.39 for ; Fri, 15 May 2009 07:52:39 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <4A0D1FF1-302-2D5C780A@nukeman.tgi-sci.com> References: <4A0D1FF1-302-2D5C780A@nukeman.tgi-sci.com> From: Grant Likely Date: Fri, 15 May 2009 08:52:19 -0600 Message-ID: Subject: Re: FEC & SDMA (bestcomm) interaction on the 5200 To: Dimiter Popoff Content-Type: text/plain; charset=ISO-8859-1 Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Fri, May 15, 2009 at 2:36 AM, Dimiter Popoff wrote: > Hi people, > > I am porting my (not linux) OS to the 5200. I went all the > way understanding how the SDMA works and programming what > I needed for it so things are now pretty stable in terms > of disk I/O and system memory -> PCI (offscreen window > buffers -> PCI display framebuffer). > > =A0And I wanted to make use of the Ethernet ("FEC", as they have > it), hoping it would take me a few days (not my first one). > > =A0I am out of luck - it is practically undocumented. There is some > talk of receive buffers which the FEC should see empty etc., > how on earth is that supposed to happen when it has no bus > master capability at all? It relies on the SDMA for its bus > activity - but in what format does it expect to get these > buffer related data? > =A0Or (more likely, at least hopefully so) this talk in the > MPC5200BUM (and MPC5200UM, for that) is just nonsense and > the FEC simply puts in the FIFO incoming packets, writing as > a last .l the receive frame status word? If so, I could > easily handle that with the SDMA. > =A0Same question about transmitting. I can only hope/assume > that the FEC will just send what it is handed through the > FIFO by the SDMA, the very first .l being the frame control > word, and ending when the TFD from the data drd1a or whatever > makes it through? It's been a long time since I've been in the bowels of the FEC driver, but I believe you are correct. g. --=20 Grant Likely, B.Sc., P.Eng. Secret Lab Technologies Ltd.