From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ovro.ovro.caltech.edu (ovro.ovro.caltech.edu [192.100.16.2]) by ozlabs.org (Postfix) with ESMTP id 1EC40B6F7B for ; Sat, 28 May 2011 00:45:06 +1000 (EST) Message-ID: <4DDFB49D.8010104@ovro.caltech.edu> Date: Fri, 27 May 2011 07:26:37 -0700 From: David Hawkins MIME-Version: 1.0 To: Bruce_Leonard@selinc.com Subject: Re: MPC8308 bursting question References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Cc: linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Bruce, > This isn't really a Linux PPC question, but this is the smartest mailing > list I know for asking PPC hardware questions, so here goes. > > We're using an MPC8308 and want to use the DMA engine to move data in and > out of an FPGA hanging on the local bus. Our bandwidth/local bus burden > calculations were done assuming that we could use bursting. So I've setup > a UPM to do single beat and burst reads/writes. I've also configured my > DMA TCD to use a data transfer size of 32-bytes when accessing the FPGA. > The problem I'm having is I can't seem to get the UPM to ever trigger the > burst write sequence using the DMA. Single beat reads and writes work > okay, but no bursting. In fact, the only thing I've been able to find in > the manual that causes a burst transaction is a cache line miss, which is > wholly in the purview of the core and really does me no good. > > Does anyone know of any way (short of issuing a run command to the UPM via > MxMR) to force a burst transaction on the 8308? Am I just being dumb and > missing something totally fundamental? Read my MPC8349EA UPM setup notes and see if you have used similar settings (I assume the local bus UPMs are similar): http://www.ovro.caltech.edu/~dwh/carma_board/carma_sys.pdf Do you have a Modelsim simulation of your interface? I have a VHDL bus-functional-model I wrote that I can send you. Cheers, Dave