From mboxrd@z Thu Jan 1 00:00:00 1970 From: Philip Balister Subject: Re: DMA example Date: Wed, 24 Feb 2010 14:31:09 -0800 Message-ID: <4B85A8AD.5060206@balister.org> References: <4B857F2F.7000201@balister.org> <20100224203555.GT28173@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mail.geekisp.com ([216.168.135.169]:21638 "EHLO starfish.geekisp.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1758178Ab0BXWbP (ORCPT ); Wed, 24 Feb 2010 17:31:15 -0500 In-Reply-To: <20100224203555.GT28173@atomide.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Tony Lindgren Cc: "linux-omap@vger.kernel.org" On 02/24/2010 12:35 PM, Tony Lindgren wrote: > * Philip Balister [100224 11:31]: >> I am trying to setup a dma operation to copy memory from GPMC >> address space into RAM. The only examples using the omap-dma api use >> hardware triggers. >> >> When I start a transfer, I end up with a DMA transaction error when >> I start the transfer. >> >> Does anyone have a good example of a software transfer? Currently, I >> am tracing the omap dma api to see how things map into the registers >> .... > > Enjoy the GPMC timings. I recommend attaching a logic analyzer there > to verify the things are right for the key lines if you have chance. > > Hmm I thought the hardware triggers were optional in at least > drivers/usb/musb/tusb6010_omap.c.. Maybe I don't remember correctly. GPMC is easy :) Basically, I have a device attached to a GPMC chip select and I need to read/write to it. The GPNC bit is fine, we'd just like to use the DMA controller to move the data. Philip