From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lars-Peter Clausen Subject: Re: [alsa-devel] [PATCH v3 4/4] ASoC: simple-card: Add DT documentation for multi-DAI links Date: Wed, 19 Mar 2014 20:31:45 +0100 Message-ID: <5329F0A1.8020801@metafoo.de> References: <20140317164339.GR11706@sirena.org.uk> <20140318091728.1d2240ca@armhf> <53296CB7.1000909@ti.com> <5329E749.6070900@metafoo.de> <5329ECC2.7040803@ti.com> <20140319192157.GW11706@sirena.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140319192157.GW11706-GFdadSzt00ze9xe1eoZjHA@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Mark Brown Cc: Jyri Sarha , Jean-Francois Moine , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, alsa-devel-K7yf7f+aM1XWsZ/bQMPhNw@public.gmane.org, Xiubo Li , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Kuninori Morimoto List-Id: alsa-devel@alsa-project.org On 03/19/2014 08:21 PM, Mark Brown wrote: > On Wed, Mar 19, 2014 at 09:15:14PM +0200, Jyri Sarha wrote: >> On 03/19/2014 08:51 PM, Lars-Peter Clausen wrote: > >>> 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. > > No, Linux has a definition of all the clock modes which applies to all > devices regardless of what the manufacturer documents in their > datasheet. > Yep. The clock properties are well defined for the different modes that can be specified in the format property. It's up to the driver to translate this to driver specific settings. If two drivers behave differently for the same mode one of them (or both) are broken. We should probably add the definitions for the different formats to the DT bindings. E.g. what is default, what is inverted polarity, etc. - Lars -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753409AbaCSTbN (ORCPT ); Wed, 19 Mar 2014 15:31:13 -0400 Received: from smtp-out-002.synserver.de ([212.40.185.2]:1044 "EHLO smtp-out-242.synserver.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752264AbaCSTbM (ORCPT ); Wed, 19 Mar 2014 15:31:12 -0400 X-SynServer-TrustedSrc: 1 X-SynServer-AuthUser: lars@metafoo.de X-SynServer-PPID: 28455 Message-ID: <5329F0A1.8020801@metafoo.de> Date: Wed, 19 Mar 2014 20:31:45 +0100 From: Lars-Peter Clausen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131103 Icedove/17.0.10 MIME-Version: 1.0 To: Mark Brown CC: Jyri Sarha , Jean-Francois Moine , devicetree@vger.kernel.org, alsa-devel@alsa-project.org, Xiubo Li , linux-kernel@vger.kernel.org, Kuninori Morimoto Subject: Re: [alsa-devel] [PATCH v3 4/4] ASoC: simple-card: Add DT documentation for multi-DAI links References: <20140317164339.GR11706@sirena.org.uk> <20140318091728.1d2240ca@armhf> <53296CB7.1000909@ti.com> <5329E749.6070900@metafoo.de> <5329ECC2.7040803@ti.com> <20140319192157.GW11706@sirena.org.uk> In-Reply-To: <20140319192157.GW11706@sirena.org.uk> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/19/2014 08:21 PM, Mark Brown wrote: > On Wed, Mar 19, 2014 at 09:15:14PM +0200, Jyri Sarha wrote: >> On 03/19/2014 08:51 PM, Lars-Peter Clausen wrote: > >>> 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. > > No, Linux has a definition of all the clock modes which applies to all > devices regardless of what the manufacturer documents in their > datasheet. > Yep. The clock properties are well defined for the different modes that can be specified in the format property. It's up to the driver to translate this to driver specific settings. If two drivers behave differently for the same mode one of them (or both) are broken. We should probably add the definitions for the different formats to the DT bindings. E.g. what is default, what is inverted polarity, etc. - Lars