From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bo Shen Date: Tue, 25 Mar 2014 08:01:26 +0000 Subject: Re: [RFC PATCH] ASoC: wm8904: add CCF support Message-Id: <533137D6.9010006@atmel.com> List-Id: References: <1395370262-23305-1-git-send-email-voice.shen@atmel.com> <20140321103747.GK23372@e106331-lin.cambridge.arm.com> <20140321115511.GM11706@sirena.org.uk> <532F9557.2000402@atmel.com> <20140324110616.GG2269@sirena.org.uk> In-Reply-To: <20140324110616.GG2269@sirena.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Mark Brown Cc: Mark Rutland , "alsa-devel@alsa-project.org" , "b.brezillon.dev@gmail.com" , "nicolas.ferre@atmel.com" , "linux-sound@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" Hi Mark, On 03/24/2014 07:06 PM, Mark Brown wrote: > On Mon, Mar 24, 2014 at 10:15:51AM +0800, Bo Shen wrote: >> On 03/21/2014 07:55 PM, Mark Brown wrote: >>> On Fri, Mar 21, 2014 at 10:37:47AM +0000, Mark Rutland wrote: >>>> On Fri, Mar 21, 2014 at 02:51:02AM +0000, Bo Shen wrote: > >>>>> + - wlf,sysclk-from-mclk: set the sys clock is driven from mclk, > >>>> Why can the kernel not decide this? > >>> It can. > >> I really don't know how it decided by kernel (hardcode in machine driver ?), >> can you point me directly? Thanks. > > It can just look to see if there is a suitable system clock present, > this shouldn't be hard. If there's a clock connected at a suitable > rate it should use that, otherwise if there's a clock at an unsuitable > rate it should either change the rate of the clock or use the FLL. I try to implement this, I think we can write the wm8904 dt as simple as following, can it be acceptable? Case 1: using SoC provided clock wm8904:wm8904@1a { compatible = "wlf,wm8904"; reg = <0x1a>; clocks = <&pck0>; clock-name = "mclk"; } Case 2: using external crystal (For this case, I have no idea to put to CCF, so need "wlf,xtal-clk-freq" property). wm8904:wm8904@1a { compatible = "wlf,wm8904"; reg = <0x1a>; wlf,xtal-clk-freq = <12000000>; } Then we use these clocks to configure FLL. Btw, I see the "wm2000.c" retrieve the clock, however not see the usage cases for it. Best Regards, Bo Shen