From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753256AbdIEVNs (ORCPT ); Tue, 5 Sep 2017 17:13:48 -0400 Received: from mail-out.m-online.net ([212.18.0.10]:36683 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752312AbdIEVNq (ORCPT ); Tue, 5 Sep 2017 17:13:46 -0400 X-Auth-Info: OChJWvDaI6b0kxRC83xwcvOau0QZd6niTE+Cb+mnEvI= Subject: Re: [PATCH] sound: soc: fsl: Do not set DAI sysclk when it is equal to system freq To: Nicolin Chen , Fabio Estevam Cc: Timur Tabi , Xiubo Li , Liam Girdwood , Mark Brown , Jaroslav Kysela , Takashi Iwai , "festevam@gmail.com" , "alsa-devel@alsa-project.org" , "linuxppc-dev@lists.ozlabs.org" , "linux-kernel@vger.kernel.org" References: <1504436701-20700-1-git-send-email-lukma@denx.de> <07e54d28-3bbc-aad2-146b-30867c0bc337@denx.de> <20170905052031.GB2774@Asurada-CZ80> <819784e1-910b-6833-997a-2097e147bd0c@denx.de> <20170905181108.GB23906@Asurada-Nvidia> From: =?UTF-8?Q?=c5=81ukasz_Majewski?= Organization: DENX Message-ID: Date: Tue, 5 Sep 2017 23:13:40 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20170905181108.GB23906@Asurada-Nvidia> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Nicolin, > On Tue, Sep 05, 2017 at 10:35:34AM +0200, Łukasz Majewski wrote: > >>> And apparently, we shouldn't set bitclk to 66MHz either. Can >>> you help to find where this 66MHz comes from? > >> 2. int asoc_simple_card_init_dai() @ simple-card-utils.c > > Oh, I just searched in the simple-card.c but missed this file. > >> In this function (point 2.) the >> simple_dai->sysclk is set and: >> snd_soc_dai_set_sysclk(dai, 0, simple_dai->sysclk, 0) >> which sets frequency to 66 MHz [*]. >> >> The asoc_simple_card_init_dai() is called in >> asoc_simple_card_dai_init() @ simple-card.c >> which is assigned to dai_link->init >> dai_link->init = asoc_simple_card_dai_init; @ simple_card.c >> >> And the sysclk itself is defined at: >> ------------------------------------- >> dai_props->codec_dai->sysclk, which is used at:a > > Why codec_dai? Why not dai_props->cpu_dai->sysclk since we are talking > about SSI? This is how the simple-card (simple-sound-card) is written. > >> asoc_simple_card_startup(), asoc_simple_card_shutdown() and others >> functions at simple-card.c >> It is setup at: >> asoc_simple_card_parse_clk() @ simple-card-utils.c from macro: >> #define asoc_simple_card_parse_clk_cpu() >> And the problem is: >> ------------------- >> >> At the >> asoc_simple_card_parse_clk() >> we finally go to dts node: >> /soc/aips-bus@02100000/i2c@021a0000/tfa9879@6C > > This tfa9879 should be the CODEC right? Yes. The tfa9879 is a codec (very simple -> I2S + I2C, mono). They key point here is the asoc_simple_card_parse_clk() function from simple-card-utils.c Please look how the clock is assigned; It first checks for cpu clock, then for "system-clock-frequency" DTS node and _finally_ looks for another "child" clock [1], which is the codec attached to I2C. And from there it takes the 66 MHz CLK: /soc/aips-bus@02100000/i2c@021a0000/tfa9879@6C > >> which has clock from I2C (66 MHz). > > You mean I2C scl or I2S sclk? I2C scl. > > ----------------------------------------------------------------- > > But anyway, I feel very confused here as you have 66MHz clock rate > (regardless of it purpose) for a codec dai but it's been passed to > a cpu dai (SSI). Please look into asoc_simple_card_parse_clk(). My DTS [1] (it is different than other in-tree supported codecs - at least I did not find similar setup in DTSes): sound { compatible = "simple-audio-card"; label = "tfa9879-mono"; simple-audio-card,dai-link { /* DAC */ format = "i2s"; bitclock-master = <&dailink_master>; frame-master = <&dailink_master>; dailink_master: cpu { sound-dai = <&ssi2>; }; codec { sound-dai = <&codec>; }; }; }; &i2c1 { clock-frequency = <400000>; pinctrl-names = "default"; pinctrl-0 = <&pinctrl_i2c1>; status = "okay"; codec: tfa9879@6C { #sound-dai-cells = <0>; compatible = "tfa9879"; reg = <0x6C>; }; }; &ssi2 { fsl,mode = "i2s-master"; status = "okay"; }; the ssi2 node is defined in imx6qdl.dtsi file (no changes). The SOC is IMX6Q. The TFA9879 is a slave for I2S transmission. > >> [*] - I could workaround this problem by setting: >> >> system-clock-frequency = <0> in >> >> dailink_master: cpu { >> sound-dai = <&ssi2>; >> }; >> >> but this is IMHO even worse hack.... than this patch. > > I haven't used simple-card for a while so I forgot how to define > its DT bindings specifically. But you should assign ssi2 as the > CPU dai and assign tfa9879 as a CODEC dai. > -- Best regards, Lukasz Majewski -- DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd@denx.de