From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: Query regarding omap_set_dma_transfer_params() Date: Tue, 12 Jun 2007 06:43:00 -0700 Message-ID: <20070612134259.GH28834@atomide.com> References: <61445c750706110756k39f09613ge0e7eedd0befe51f@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <61445c750706110756k39f09613ge0e7eedd0befe51f@mail.gmail.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-omap-open-source-bounces+gplao-linux-omap-open-source=gmane.org@linux.omap.com Errors-To: linux-omap-open-source-bounces+gplao-linux-omap-open-source=gmane.org@linux.omap.com To: "Pharaoh ." Cc: linux-omap-open-source@linux.omap.com List-Id: linux-omap@vger.kernel.org * Pharaoh . [070611 08:02]: > Hi, > > I am trying to configure the DMA channels in my ALSA driver. Functions > like > > > void omap_set_dma_dest_params(int lch, int dest_port, int dest_amode, > unsigned long dest_start, > int dst_ei, int dst_fi) > and omap_set_dma_src_params() are used for configuration. > > What the last two fields i.e dst_ie and dst_fi mean here? See dma.h, ei = element index and fi = frame index. Some of these are documented in the 2912 TRM pdf. > I think this has to do something with interrupts etc but not sure about it. > Also > I couldn't see those fields being populated anywhere in source (they are 0 > everywhere). > I am referring 2.6.19-omap1. > > Also, I think that these are unnecessarily exported, since the function > omap_set_dma_params() > is already exported and it calls the above mentioned functions. And > normally the sequence of > configuring the DMA channel is like > > -set src params > -set dest params > -set transfer params Well you can do it both ways, sometimes you just want to update the source or destination between transfers. Tony