From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Ujfalusi Subject: Re: [PATCH 1/6] ASoC: OMAP mcbsp: Add DSP_A support Date: Wed, 8 Apr 2009 09:01:18 +0300 Message-ID: <200904080901.18705.peter.ujfalusi@nokia.com> References: <1239020372-8457-1-git-send-email-peter.ujfalusi@nokia.com> <200904070819.12019.peter.ujfalusi@nokia.com> <20090407221404.GA8465@sirena.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Received: from mgw-mx06.nokia.com (smtp.nokia.com [192.100.122.233]) by alsa0.perex.cz (Postfix) with ESMTP id 39B44245CA for ; Wed, 8 Apr 2009 08:01:29 +0200 (CEST) In-Reply-To: <20090407221404.GA8465@sirena.org.uk> Content-Disposition: inline List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: ext Mark Brown Cc: "sakoman@gmail.com" , "alsa-devel@alsa-project.org" , "Nikula Jarkko (Nokia-D/Helsinki)" List-Id: alsa-devel@alsa-project.org On Wednesday 08 April 2009 01:14:05 ext Mark Brown wrote: > On Tue, Apr 07, 2009 at 08:19:11AM +0300, Peter Ujfalusi wrote: > > twl4030: Samples the data on falling edge, shifts data out (and changes > > the FS) on rising edge > > tlv320aic23: Samples the data on rising, shifts data out (and changes t= he > > FS) on falling edge > > What ASoC expects for DSP mode is that the data can be sampled on either > the first (mode B) or second (mode A) rising edge of BCLK after a rising > edge of LRCLK. This implies that the data should be driven on the > falling edge of BCLK. > > The TLV320AIC23 can do either mode - the description on page 24 matches > exactly. Unless I'm missing something the inversion of the frame clock > for osk5912 looks like a mistake. I'd need to read the code a bit more > closely to check I've not missed something but it looks like the codec > driver is never actually setting LRP so it's got the mode the wrong way > round for the one it supports. I have been also wondering about the missing LRP handling, but I do not hav= e = access to osk5912 board neither to tlv320aic32 codec... > > The TWL4030 datasheet does not appear to be a model of clarity in this > area but it looks awfully like mode A with an inverted bit clock (the > data appears to be being driven rather than sampled on the rising edge > but the first bit does start on the falling edge of the frame clock). Well, in general there are lots of these kind of 'small' details missing fr= om = the documentation. One just have to try it out and see how it behaves ;) > This means the Beagle code looks about right unless I'm misreading > something. Does it means that the DSP_A addition is also correct? I have it drawn to = paper, how the configuration in omap-mcbsp used by the beagle in 4 channel = mode would look like, and it does look 100% as the TDM mode described in th= e = twl datasheet... BTW: when the twl is in 4 channel mode, it has to be the master on the bus = (small thing, since twl usually is the master on the bus anyway) -- = P=E9ter