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: Tue, 7 Apr 2009 08:19:11 +0300 Message-ID: <200904070819.12019.peter.ujfalusi@nokia.com> References: <1239020372-8457-1-git-send-email-peter.ujfalusi@nokia.com> <20090406122232.GA8585@rakim.wolfsonmicro.main> <200904061537.59067.peter.ujfalusi@nokia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Received: from mgw-mx09.nokia.com (smtp.nokia.com [192.100.105.134]) by alsa0.perex.cz (Postfix) with ESMTP id AB1002442B for ; Tue, 7 Apr 2009 07:19:17 +0200 (CEST) In-Reply-To: <200904061537.59067.peter.ujfalusi@nokia.com> 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: alsa-devel@alsa-project.org Cc: "sakoman@gmail.com" , ext Mark Brown , "Nikula Jarkko (Nokia-D/Helsinki)" List-Id: alsa-devel@alsa-project.org On Monday 06 April 2009 15:37:58 Ujfalusi Peter (Nokia-D/Tampere) wrote: > On Monday 06 April 2009 15:22:33 ext Mark Brown wrote: > > On Mon, Apr 06, 2009 at 03:19:27PM +0300, Peter Ujfalusi wrote: > > > Add SND_SOC_DAIFMT_DSP_A support for omap-mcbsp. > > > The configuration for DSP_A and DSP_B is the same. > > > > That doesn't sound right - the two formats do differ on the wire. In > > mode B the MSB of data is transmitted along with the LRC pulse while in > > mode A it is transmitted after the trailing edge of the LRC pulse. > > That is why I have asked previously about these... I'm still a bit > confused, but at the end (I think) the configuration in omap-mcbsp is rig= ht > for the twl4030: > regs->srgr2 |=3D FPER(wlen * channels - 1); > regs->srgr1 |=3D FWID(wlen * channels - 2); > and > /* 0-bit data delay */ > regs->rcr2 |=3D RDATDLY(0); > regs->xcr2 |=3D XDATDLY(0); > > I'll revisit this. I have taken a look about the DSP_A and DSP_B modes in omap-mcbsp. The only board uses the DSP_B mode is the osk5912 with the tlv320aic23 code= c. I have downloaded the data sheet for the tlv320aic23 and I think that the D= SP = mode in tlv320aic23 is identical to the TDM mode in twl4030 except for the = clock polarity 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 the F= S) = on falling edge This difference is taken care with the SND_SOC_DAIFMT_NB_IF (osk5912) and = SND_SOC_DAIFMT_IB_NF (beagle). I would say, that I'm still confused over this... References: tlv320aic23: http://focus.ti.com/lit/ds/slws106d/slws106d.pdf Page 28 (3-8) twl4030: http://focus.tij.co.jp/jp/lit/ug/swcu050b/swcu050b.pdf Page 712 (TDM mode, Sample length 16 bits; Word length 16 bits) -- = P=E9ter