From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: DMA example Date: Wed, 24 Feb 2010 14:52:31 -0800 Message-ID: <20100224225231.GA28173@atomide.com> References: <4B857F2F.7000201@balister.org> <20100224203555.GT28173@atomide.com> <4B85A8AD.5060206@balister.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mho-01-ewr.mailhop.org ([204.13.248.71]:63017 "EHLO mho-01-ewr.mailhop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758042Ab0BXWvb (ORCPT ); Wed, 24 Feb 2010 17:51:31 -0500 Content-Disposition: inline In-Reply-To: <4B85A8AD.5060206@balister.org> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Philip Balister Cc: "linux-omap@vger.kernel.org" * Philip Balister [100224 14:28]: > 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 :) Sounds like you just got lucky! :) > 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. That should work, at least there has been several memory-to-memory dma test modules posted here over the years. Have you tried using OMAP_DMA_NO_DEVICE for omap_request_dma? Also search for omap dmatest or similar. Tony