From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre-Louis Bossart Subject: Re: [PATCH v4 6/8] ASoC: compress: Add support for DAI multicodec Date: Thu, 03 Jul 2014 14:09:11 -0500 Message-ID: <53B5AA57.5060804@linux.intel.com> References: <53B400DE.3040205@baylibre.com> <20140703064147.GK2296@intel.com> <53B539E8.1000301@baylibre.com> <53B53C6B.8020707@metafoo.de> <53B540EE.30009@baylibre.com> <53B541F0.1040105@metafoo.de> <53B5428F.9050100@baylibre.com> <20140703120613.GP2296@intel.com> <20140703121846.GB410@sirena.org.uk> <20140703161517.GQ2296@intel.com> <20140703183804.GO410@sirena.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by alsa0.perex.cz (Postfix) with ESMTP id 7598A26590C for ; Thu, 3 Jul 2014 21:09:17 +0200 (CEST) In-Reply-To: <20140703183804.GO410@sirena.org.uk> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: Mark Brown , Vinod Koul Cc: alsa-devel@alsa-project.org, Lars-Peter Clausen , misael.lopez@ti.com, Benoit Cousson , lgirdwood@gmail.com List-Id: alsa-devel@alsa-project.org >>> The use case tends to be for applications that have one device per >>> physical output. This isn't normally mobile, it's normally high >>> performance audio applications where people are doing things to try to >>> electrically isolate the analogue outputs or dealing with high power so >>> need to keep speaker outputs physically separate. I can imagine set top >>> box type applications (which do use offloaded media decode) doing this. > >> Not sure if I follow you, I have no idea of how these systems work. > > They're having the SoC play stereo (or whatever) data and then having > multiple CODECs on the bus, each parsing some subset of the channels > (typically one channel per CODEC). This sort of stream aggregation/split is a very valid use case that's coming to mobiles in the very near future with new interfaces being standardized. > >> So how can we have a situation where we have compressed device linked to >> multiple codecs? > > If it's intended to be DPCM only (which it iss now I think about it) it > sounds like you can't have it linked to *any* real CODECS, at least not > directly! there are very few references to codec_dais in soc-compress and some are in sections copy/pasted from soc-pcm, which makes me wonder as well if they needed to be there in the first place. -Pierre