From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jyri Sarha Subject: Re: [alsa-devel] [PATCH v3 4/4] ASoC: simple-card: Add DT documentation for multi-DAI links Date: Wed, 19 Mar 2014 21:15:14 +0200 Message-ID: <5329ECC2.7040803@ti.com> References: <20140317164339.GR11706@sirena.org.uk> <20140318091728.1d2240ca@armhf> <53296CB7.1000909@ti.com> <5329E749.6070900@metafoo.de> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5329E749.6070900@metafoo.de> Sender: linux-kernel-owner@vger.kernel.org To: Lars-Peter Clausen Cc: Jean-Francois Moine , Mark Brown , devicetree@vger.kernel.org, alsa-devel@alsa-project.org, Xiubo Li , linux-kernel@vger.kernel.org, Kuninori Morimoto List-Id: devicetree@vger.kernel.org On 03/19/2014 08:51 PM, Lars-Peter Clausen wrote: > On 03/19/2014 11:08 AM, Jyri Sarha wrote: > [...] >> It may sometimes be helpful to allow overwriting link level settings >> in dai >> level. In order to do that it should be possible to write all daifmt >> settings explicitly like this: >> >> bitclock-inversion = <0>; /* <0> = no bitclock-inversion */ > > When does this make sense? Either the bitclock is inverted for all of > them or for none. > Definition of clock signal and it's inversion varies between chip manufacturers and sometimes it may not be possible to get all the dai drivers to work identically in this respect. Because of this in some cases there may be a need to set the inversion bit only at one end of the link. I think there was an example of this in some mail regarding the simple-card DT-bidings, but I can't find it ATM. Best regards, Jyri