From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752249AbdIFSf6 (ORCPT ); Wed, 6 Sep 2017 14:35:58 -0400 Received: from mail-out.m-online.net ([212.18.0.9]:36515 "EHLO mail-out.m-online.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750807AbdIFSf5 (ORCPT ); Wed, 6 Sep 2017 14:35:57 -0400 X-Auth-Info: UKVzBPvP0NgYM7P8uPgPVdJGza7AGviC3Et1YTreVrA= Subject: Re: [PATCH] sound: soc: fsl: Do not set DAI sysclk when it is equal to system freq To: Nicolin Chen Cc: Fabio Estevam , 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> <20170905225225.GA14132@Asurada-Nvidia> <20170906173348.GA28104@Asurada-Nvidia> From: =?UTF-8?Q?=c5=81ukasz_Majewski?= Organization: DENX Message-ID: <69352458-2e90-a847-2c2f-bba259a32162@denx.de> Date: Wed, 6 Sep 2017 20:35:50 +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: <20170906173348.GA28104@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 Wed, Sep 06, 2017 at 11:22:48AM +0200, Łukasz Majewski wrote: > >>> Here is the routine that I understood from the code: >>> 1) asoc_simple_card_parse_clk_cpu(dev, cpu, dai_link, cpu_dai); >>> => asoc_simple_card_parse_clk(dev, cpu, // cpu node in sound{} [1] >>> dai_link->cpu_of_node, // node ssi2 [2] >>> cpu_dai, dai_link->cpu_dai_name); >>> ==> 1.1) devm_get_clk_from_child(dev, node, NULL); // [1] >>> ==> 1.2) of_property_read_u32(node, "system-clock-frequency", &val)// [1] >>> ==> 1.3) devm_get_clk_from_child(dev, dai_of_node, NULL); // [2] > >>> For the cpu routine, it first checks for clock property under cpu >>> node of simple-card, then for "system-clock-frequency" in the cpu >>> node of simple-card, and finally looks for clock property in ssi2 >>> node. > >> -----> dev: sound >> -----> clk node: /soc/aips-bus@02000000/spba-bus@02000000/ssi@0202c000 >> -----> Clk asignment >> >> And this clock is taken from this node. It looks like ipg clock for ssi... > > This makes sense now. The devm_get_clk_from_child() in 1.3) fetched > the first clock of ssi2 -- ipg clock. Yes, exactly (for SSI2) [1]: clocks = <&clks IMX6QDL_CLK_SSI2_IPG>, <&clks IMX6QDL_CLK_SSI2>; clock-names = "ipg", "baud"; > >> The problem is with the "lack" of clock nodes/properties at >> >> dailink_master: cpu { >> sound-dai = <&ssi2>; >> clock = <&SSSS>; If possible I do prefer a solution, which uses only DTS. Side question - how to refer to baud clock from [1]? >> system-clock-frequency = ; >> }; > > This is the right solution based on current simple-card driver. For > SSI (having two clocks), you have to specify the baud clock in the > cpu node like that. I believe this is what the simple-card designer > expected users to do since the cpu node is the first place that the > driver tries to look at. I will give a shoot the option with adding the ipg clock. > >> I think that the proper solution would be to add check for: >> >> freq < sysclk/5 in fsl_ssi_set_dai_sysclk() and return -ENOTSUPP to >> make the simple-audo-card driver happy (and not introducing >> regressions). > > As I said in the first place, adding another check in set_sysclk() > is not that essential but seems to be plausible to me. So I am okay > if you really want to have that. > Thanks for help. -- 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