Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752941AbaBXQTv (ORCPT ); Mon, 24 Feb 2014 11:19:51 -0500 Received: from [65.55.88.14] ([65.55.88.14]:53393 "EHLO tx2outboundpool.messaging.microsoft.com" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751867AbaBXQTs convert rfc822-to-8bit (ORCPT ); Mon, 24 Feb 2014 11:19:48 -0500 X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPV:NLI;H:mail.freescale.net;RD:none;EFVD:NLI X-SpamScore: -2 X-BigFish: VS-2(zz98dIc89bh1432Izz1f42h2148h208ch1ee6h1de0h1fdah2073h2146h1202h1e76h2189h1d1ah1d2ah21bch1fc6hzzz2dh2a8h839h93fhd25hd2bhf0ah1288h12a5h12a9h12bdh137ah13b6h1441h1504h1537h153bh162dh1631h1758h18e1h1946h19b5h1ad9h1b0ah1b2fh2222h224fh1fb3h1d0ch1d2eh1d3fh1dfeh1dffh1fe8h1ff5h209eh2216h22d0h2336h2438h2461h2487h24d7h2516h2545h255eh1155h) Date: Tue, 25 Feb 2014 00:06:49 +0800 From: Nicolin Chen To: "Austin, Brian" CC: Mark Brown , "Handrigan, Paul" , "robh+dt@kernel.org" , "pawel.moll@arm.com" , "mark.rutland@arm.com" , "ijc+devicetree@hellion.org.uk" , "galak@codeaurora.org" , "rob@landley.net" , Liam Girdwood , "grant.likely@linaro.org" , "devicetree@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "alsa-devel@alsa-project.org" Subject: Re: [PATCH] ASoC: cs42888: Add codec driver support Message-ID: <20140224160648.GC6132@MrMyself> References: <1393224929-7555-1-git-send-email-Guangyu.Chen@freescale.com> <20140224113011.GE25940@sirena.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Content-Transfer-Encoding: 8BIT X-OriginatorOrg: freescale.com X-FOPE-CONNECTOR: Id%0$Dn%*$RO%0$TLS%0$FQDN%$TlsDn% Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 24, 2014 at 03:52:24PM +0000, Austin, Brian wrote: > >> + if (!IS_ERR(cs42888->clk)) > >> + clk_disable_unprepare(cs42888->clk); > > > > Does the device work without MCLK? > Yes, MCLK is required. If you can’t get the clock you should error out. Wait...Regarding this clock part, I just forgot the reason I put the code: 385 cs42888->clk = devm_clk_get(&i2c->dev, "mclk"); 386 if (IS_ERR(cs42888->clk)) 387 dev_warn(&i2c->dev, "failed to get the clock: %ld\n", 388 PTR_ERR(cs42888->clk)); was because the MCLK might be provided from SoC (DAI master) so it could be totally controlled by CPU DAI driver, ESAI for example has its own dividers to derive the HCKT clock (MCLK for Tx) from ahb clock in SoC clock tree, in which case we might not easily pass a valid clock phandle via DT. (RFC to this thought.) Thank you, Nicolin Chen -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/