From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933606AbcA0RNN (ORCPT ); Wed, 27 Jan 2016 12:13:13 -0500 Received: from mailapp01.imgtec.com ([195.59.15.196]:8267 "EHLO mailapp01.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933117AbcA0RNL (ORCPT ); Wed, 27 Jan 2016 12:13:11 -0500 Subject: Re: [RFC V2 1/2] ASoC: img: Add binding document for Pistachio audio card To: Mark Brown References: <1453818867-16322-1-git-send-email-Damien.Horsley@imgtec.com> <1453818867-16322-2-git-send-email-Damien.Horsley@imgtec.com> <20160127145756.GR6042@sirena.org.uk> <56A8DFBC.6070007@imgtec.com> <20160127160057.GA25316@sirena.org.uk> CC: , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Liam Girdwood , Jaroslav Kysela , Takashi Iwai , , , James Hartley From: Damien Horsley X-Enigmail-Draft-Status: N1110 Message-ID: <56A8FAA5.1000907@imgtec.com> Date: Wed, 27 Jan 2016 17:13:09 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20160127160057.GA25316@sirena.org.uk> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.167.68] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 27/01/16 16:00, Mark Brown wrote: > On Wed, Jan 27, 2016 at 03:18:20PM +0000, Damien Horsley wrote: >> On 27/01/16 14:57, Mark Brown wrote: >>> On Tue, Jan 26, 2016 at 02:34:26PM +0000, Damien Horsley wrote: > >>>> + - clock-names : Includes the following entries: >>>> + "audio_pll" The audio PLL >>>> + "i2s_mclk" The i2s reference clock >>>> + Also connected to i2s_out_0_mclk output >>>> + "dac_mclk" Dac reference clock. Connected to i2s_dac_clk output > >>> Why are these (especially the dac_mclk and i2s_mclk) properties of the >>> card and not of the drivers for the respective devices? > >> Due to the shared nature of these clocks. Individual components cannot >> be responsible for controlling these as this could break configurations >> for other components that are sharing the clocks. Only the card driver >> has visibility of all of the components and their requirements. > > You're talking about the code that decides what rates to set the clock > at, not where the properties are placed in the DT. > >> i2s_mclk and dac_mclk can be used by both the i2s in and i2s out paths >> on some boards > > Multiple devices can reference the same clock. > audio_pll is referenced exclusively by the card device i2s_mclk and dac_mclk can also be referenced by other devices. The i2s out controller references i2s_mclk, and codec devices can reference i2s_mclk/dac_mclk dependent on their system clock requirements without a reference to i2s_mclk and dac_mclk in the card driver, it would not be possible to control the divisors and gates for these clocks in the following cases: Simplistic codecs that do not have drivers Codec drivers that do not call clk_set_rate and clk_enable/clk_disable