From mboxrd@z Thu Jan 1 00:00:00 1970 From: Charles Keepax Subject: Re: [PATCH 2/2] ASoc: wm8731: add normal mode with 12MHz XTAL Date: Mon, 20 Jun 2016 11:55:40 +0100 Message-ID: <20160620105540.GI1552@localhost.localdomain> References: <1465517516-1917-1-git-send-email-flatmax@flatmax.org> <1465517516-1917-2-git-send-email-flatmax@flatmax.org> <575BD6F2.70600@flatmax.org> <575CD572.2040700@flatmax.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mx0a-001ae601.pphosted.com (mx0a-001ae601.pphosted.com [67.231.149.25]) by alsa0.perex.cz (Postfix) with ESMTP id 1C0C026507F for ; Mon, 20 Jun 2016 12:55:31 +0200 (CEST) Content-Disposition: inline In-Reply-To: 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: Rob Calhoun Cc: alsa-devel@alsa-project.org, broonie@kernel.org, patches@opensource.wolfsonmicro.com, Matt Flax List-Id: alsa-devel@alsa-project.org On Sun, Jun 19, 2016 at 05:46:02PM -0400, Rob Calhoun wrote: > Hi Matt, > > Based on my experience with the WM8737, the bitclock will always run > at 12 MHz on these devices in USB mode. While the carrying capacity of > the channel is always 12 Mbps, the data put on the wire by the codec > depend on the sample rate, number of channels, and bit depth. This > leaves some unused capacity in the channel. It is the responsibility > of the receiving digital audio interface to pull off the appropriate > number of bits every time the LRCLK/frameclock fires and ignore the > rest of it. For example in I2S mode, 2-channel, 32-bit, the DAI should > pull off the first 32 bits following each LRCLK transition. Thanks very much for adding this, sounds like this is basically how the part operates then. Although I feel the datasheet could have been more clear, apologies for that. Thanks, Charles