From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Ujfalusi Subject: Re: Reg: Implementation of GSM digital audio path Date: Thu, 25 Jun 2009 14:32:48 +0300 Message-ID: <200906251432.49009.peter.ujfalusi@nokia.com> References: <1cbe56070906250247j30e63925k3acbff5a5a3e3df8@mail.gmail.com> <200906251335.08412.peter.ujfalusi@nokia.com> <1cbe56070906250411l25762a2dkce4cad25a7a293ab@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Received: from mgw-mx09.nokia.com (smtp.nokia.com [192.100.105.134]) by alsa0.perex.cz (Postfix) with ESMTP id 3C4ED103873 for ; Thu, 25 Jun 2009 13:32:58 +0200 (CEST) In-Reply-To: <1cbe56070906250411l25762a2dkce4cad25a7a293ab@mail.gmail.com> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: alsa-devel@alsa-project.org Cc: ext shariff List-Id: alsa-devel@alsa-project.org On Thursday 25 June 2009 14:11:04 ext shariff wrote: > Hi Peter, > > Thanks for quick response. I understood some what from your mail. > > I will explain, how my hardware is connected. > > > USB GSM chip -> McBSP3 > > McBSP2 -> TWL4030 > > Here, playback functionality will not be there in the GSM path. I > need to take audio data from GSM. and redirect this to TWL4030 codec. I see. Sorry I have confused things a bit, In this case you need to do what Mark has suggested: dummy dai for the codec, connect it to McBSP3 as it were a normal codec. Than you will have two PCM on the sound card: 0.0: TWL digital audio 0.1: Your codec arecord -Dplughw:0.1 | aplay -Dplughw:0.0 or arecord -Dhw:0.1 | aplay -Dhw:0.0 > > The thing is, How and where to implement this GSM path without > playback? as I am new to this ASoC framework. > > What I understood from ur mail is. Audio is being redirected from > the application space i.e arecord will record and store in buffer and this > buffer is > > being played using aplay to other hardware (twl4030). > > Can we handle the same thing in kernel space ( i.e in driver itself= ). You anyway have to copy from one buffer to another to be in the safe side (= in = theory you could use the same buffer for recording and playback, but it sho= uld = be avoided). So you have to copy the samples from the capture buffer to the playback = buffer. It really does not matter if it is done inside of the kernel or in = user space. This kind of 'routing' clearly belongs to the user space. > > Regards, > Shariff -- = P=E9ter