From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?Daniel_Gl=F6ckner?= Subject: Re: [patch] tlv320aic3x: disable ADC/DAC while changing clock Date: Mon, 30 Mar 2009 14:48:09 +0200 Message-ID: <49D0BF89.4050100@emlix.com> References: <1238073706-23821-1-git-send-email-dg@emlix.com> <20090326134528.GC3771@sirena.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: Received: from mx1.emlix.com (mx1.emlix.com [193.175.82.87]) by alsa0.perex.cz (Postfix) with ESMTP id 3E8A31037FD for ; Mon, 30 Mar 2009 14:48:10 +0200 (CEST) In-Reply-To: <20090326134528.GC3771@sirena.org.uk> 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: Mark Brown Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org On 03/26/2009 02:45 PM, Mark Brown wrote: > On Thu, Mar 26, 2009 at 02:21:46PM +0100, Daniel Gl??ckner wrote: >> The aforementioned rule implies that we can not disable the PLL in >> stand-by bias level. > = > Could you go into more detail on why you believe that this is the case? > The DACs and ADCs won't be operational when the bias is held at standby > which means that at most standby needs to wait for them to go idle. This is based on the fact that soc_pcm_prepare calls snd_soc_dapm_stream_event(..., SND_SOC_DAPM_STREAM_START) before snd_soc_dapm_set_bias_level(..., SND_SOC_BIAS_ON). In addition there is a block of code in tlv320aic3x.c that explicitly disab= les the ADC/DAC in SND_SOC_BIAS_OFF. It may be superfluous, though. >> +static u8 aic3x_power_codec(struct snd_soc_codec *codec, u8 new) >> +{ > = > This really needs some comments explaining what it's doing; it's not > really clear what effect it's trying to achieve or how it interacts with > DAPM. This function takes a bitmask of the desired power state of the ADC/DAC blo= cks and configures the device accordingly. It returns a bitmask of the previous power state, suitable for input. Daniel -- = Dipl.-Math. Daniel Gl=F6ckner, emlix GmbH, http://www.emlix.com Fon +49 551 30664-0, Fax -11, Bahnhofsallee 1b, 37081 G=F6ttingen, Germany Gesch=E4ftsf=FChrung: Dr. Uwe Kracke, Dr. Cord Seele, Ust-IdNr.: DE 205 198= 055 Sitz der Gesellschaft: G=F6ttingen, Amtsgericht G=F6ttingen HR B 3160 emlix - your embedded linux partner