From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Brown Subject: Re: About the platform_name field in snd_soc_dai_link Date: Tue, 10 Aug 2010 14:47:55 +0100 Message-ID: <20100810134755.GC6416@rakim.wolfsonmicro.main> References: <20100810133818.GL27749@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from opensource2.wolfsonmicro.com (opensource.wolfsonmicro.com [80.75.67.52]) by alsa0.perex.cz (Postfix) with ESMTP id 5F8DB24459 for ; Tue, 10 Aug 2010 15:47:56 +0200 (CEST) Content-Disposition: inline In-Reply-To: <20100810133818.GL27749@pengutronix.de> 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: Sascha Hauer Cc: alsa-devel@alsa-project.org, Liam Girdwood List-Id: alsa-devel@alsa-project.org On Tue, Aug 10, 2010 at 03:38:18PM +0200, Sascha Hauer wrote: > I'm wondering what exactly a snd_soc_platform is. Apparently the > snd_pcm_ops/pcm_new/pcm_free are specific to a platform. For my > understanding these operations are more specific to a cpu_dai. Looking > at the tree it seems that each cpu_dai has exactly one possible > platform, which seems logical to me because the cpu_dai knows how to > transfer the data. They're for the DMA bit of the CPU. While most platforms have a single DMA controller (though some have more than one) it's moderately common to have more than one DAI (eg, dedicated I2S and DSP mode controllers rather than a programmable serial port, or an AC'97 controller) so it's useful to share the DMA code. > My problem on i.MX is that I currently have two possible cpu dais > (imx-ssi.[01]) and each can be configured to use dma or fiq depending > on the dma capabilities. So the cpu_dai knows which pcm_ops we have > to use, but currently it's the soc glue code which has to decide in > platform_name. Am I understanding something wrong here? This is mostly a holdover from the existing (current mainline) ASoC structuring at the minute, that also has the DMA configured per machine. This may change depending on future hardware requirements, though.