From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay03.roc.ny.frontiernet.net (relay03.roc.ny.frontiernet.net [66.133.131.36]) by ozlabs.org (Postfix) with ESMTP id BCCB02BDF2 for ; Fri, 29 Oct 2004 04:00:56 +1000 (EST) Message-ID: <006301c4bd18$59cfc570$0301a8c0@chuck2> From: "Mark Chambers" To: "Stefan Nickl" References: <1098984003.11434.12.camel@lucy.pep-kaufbeuren.de> Date: Thu, 28 Oct 2004 14:02:46 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Cc: linuxppc-embedded@ozlabs.org Subject: Re: All-ones problem with FCC1 on MPC8541 List-Id: Linux on Embedded PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , > I checked port configuration and clock routing registers in > cpm2_io/fcc_enet.c again and again, but all I get in and out is ones. > > The packet sizes I receive look reasonable, but the buffers are > filled only with 0xff. The same goes for sending, the contents > of the buffers are OK (dhcp discover...), but when capturing > the output on the other side with ethereal, the packet is again > all 0xff. > > We just discovered that apparently preamble, frame delimiter and FCS go > out over the MII (at least TxD[0:3] change state), so I don't suspect a > hardware bug. > I would guess the problem is at the DMA level, that the FCC is reading/writing ffs to/from memory for some reason. The preamble and FCS come from the FCC itself, not memory, so that's why you see them. I'd guess some kind of mismatch with the kind of cycles generated by the FCC DMA and the memory controllers. Mark Chambers