From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt Flax Subject: Re: [PATCH 2/2] ASoc: wm8731: add normal mode with 12MHz XTAL Date: Mon, 13 Jun 2016 22:39:22 +1000 Message-ID: <575EA97A.7050207@flatmax.org> References: <1465517516-1917-1-git-send-email-flatmax@flatmax.org> <1465517516-1917-2-git-send-email-flatmax@flatmax.org> <575BD6F2.70600@flatmax.org> <575CD572.2040700@flatmax.org> <20160613083714.GU20422@localhost.localdomain> <575E80B2.3040309@flatmax.org> <20160613115910.GV20422@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from nskntmtas04p.mx.bigpond.com (nskntmtas04p.mx.bigpond.com [61.9.168.146]) by alsa0.perex.cz (Postfix) with ESMTP id 7CACD265099 for ; Mon, 13 Jun 2016 14:39:29 +0200 (CEST) Received: from nskntcmgw06p ([61.9.169.166]) by nskntmtas04p.mx.bigpond.com with ESMTP id <20160613123926.VJGL2065.nskntmtas04p.mx.bigpond.com@nskntcmgw06p> for ; Mon, 13 Jun 2016 12:39:26 +0000 Received: from localhost ([::1] helo=[127.0.0.1]) by meb with esmtp (Exim 4.84_2) (envelope-from ) id 1bCRCd-0006tj-Tm for alsa-devel@alsa-project.org; Mon, 13 Jun 2016 22:42:55 +1000 In-Reply-To: <20160613115910.GV20422@localhost.localdomain> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org OK - I will look into that futher. Thanks for the info. Is it possible to look at patch 1/2 in this series ? thanks Matt On 13/06/16 21:59, Charles Keepax wrote: > On Mon, Jun 13, 2016 at 07:45:22PM +1000, Matt Flax wrote: >> On 13/06/16 18:37, Charles Keepax wrote: >>> On Sun, Jun 12, 2016 at 01:22:26PM +1000, Matt Flax wrote: >>>> It appears that my logic here is flawed. >>>> From what I can tell, it isn't possible to get a suitable bit clock out of >>>> the codec when using a 12 MHz crystal. For that reason, in my hardware I >>>> will change crystals from 12 MHz. >>> This looks correct the chip only has simple dividers so you won't >>> be able to get a good audio rate clock from a 12MHz crystal. >>> >>>> I just want to check ... are there any versions of this codec which output >>>> the bit clock when in USB mode on the BCLK pin ? >>>> >>> Apologies I am not quite sure I follow what USB mode is in this >>> context, and the bit clock surely always comes out of the BCLK >>> pin. Do you simply mean a system with a clock speed that >>> relates to the 48MHz USB clock, such as your 12MHz? Basically any >>> part that has a PLL/FLL should work for that, for example the >>> wm8998: >>> >>> http://www.cirrus.com/en/products/pro/detail/P1265.html >> Literally, with the chip set to usb mode (register 0b0001000 bit 0, page 41 >> of the data sheet) it appears that the 12 MHz clock comes out of the BCLK >> pin, rather then the bit clock. > Ah seems there are two versions of the chip the MC and L I was > looking at the datasheet for the version that doesn't have that > mode. > > From that datasheet it looks like it should be possible to > support audio rate clocks from a 12MHz input. Although as you say > the 44.1 clock is not exactly 44.1. I am not sure why you are > getting 12MHz coming out of the BCLK pin the datasheet certainly > does not appear to suggest this should happen. Are you sure the > sample rate and clock divider registers are set sensibly? My > first guess would be if things are in an unsupported state then > perhaps it just fires the clock straight through. I assume we are > very sure the input clock is 12MHz? Only other thing I can > imagine is for some reason we have a higher clock rate than we > expected and on the scope it would be hard to differenciate > between 12.288MHz and 12MHz dead. So for example if it was a > 48MHz USB clock coming in rather than 12, then the chip tries to > generate a 3.072MHz bit clock that would look like 12MHz. > > Again I guess a newer part with an PLL might be simpler as you > can simply use the PLL to generate audio rate clocks from the > 12MHz. > > Thanks, > Charles > _______________________________________________ > Alsa-devel mailing list > Alsa-devel@alsa-project.org > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel