From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3D0FDC2D0BF for ; Wed, 18 Dec 2019 16:23:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E00E24650 for ; Wed, 18 Dec 2019 16:23:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727433AbfLRQXv (ORCPT ); Wed, 18 Dec 2019 11:23:51 -0500 Received: from mga03.intel.com ([134.134.136.65]:15079 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726985AbfLRQXu (ORCPT ); Wed, 18 Dec 2019 11:23:50 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 18 Dec 2019 08:23:49 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,330,1571727600"; d="scan'208";a="415881663" Received: from dshoemak-mobl.amr.corp.intel.com (HELO [10.251.3.243]) ([10.251.3.243]) by fmsmga005.fm.intel.com with ESMTP; 18 Dec 2019 08:23:47 -0800 Subject: Re: [alsa-devel] [PATCH 10/10] ASoC: Add codec component for AD242x nodes To: Daniel Mack , linux-kernel@vger.kernel.org, linux-gpio@vger.kernel.org, linux-i2c@vger.kernel.org, alsa-devel@alsa-project.org, devicetree@vger.kernel.org, linux-clk@vger.kernel.org Cc: lars@metafoo.de, sboyd@kernel.org, mturquette@baylibre.com, robh+dt@kernel.org, broonie@kernel.org, pascal.huerst@gmail.com, lee.jones@linaro.org References: <20191209183511.3576038-1-daniel@zonque.org> <20191209183511.3576038-12-daniel@zonque.org> <0565e5cd-9a6e-db65-0632-0bc1aa1d79db@linux.intel.com> <35e7e6e7-7c70-785c-bdf3-79089134699e@zonque.org> From: Pierre-Louis Bossart Message-ID: Date: Wed, 18 Dec 2019 09:32:40 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <35e7e6e7-7c70-785c-bdf3-79089134699e@zonque.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/18/19 3:49 AM, Daniel Mack wrote: > Hi, > > On 12/17/19 8:28 PM, Pierre-Louis Bossart wrote: >> On 12/9/19 12:35 PM, Daniel Mack wrote: > >>> +    if (!ad242x_node_is_master(priv->node) && >>> +       ((format & SND_SOC_DAIFMT_MASTER_MASK) != >>> SND_SOC_DAIFMT_CBM_CFM)) { >>> +        dev_err(component->dev, "slave node must be clock master\n"); >>> +        return -EINVAL; >>> +    } >> >> It was my understanding that the master node provides the clock to the >> bus, so not sure how it could be a clock slave, and conversely how a >> slave node could provide a clock to the bus? > > The slave nodes receive the A2B clock from the master node and then > produce digital audio output that is sent to other components such as > codecs. Hence, in ASoC terms, they are the clock master. > > Likewise, as the master node is receiving its clock from other > components, it has to be a clock slave in the audio network. > > Does that make sense? Your slave node acts as a bridge then, but it seems you don't model the bus-facing interface, which has to follow the master clock. Or do you? Likewise the master has an 'SOC-facing' interface and a bus-facing interface. it *could* be master on both if ASRC was supported. The point is that the bus-facing interface is not clock slave.