From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754616AbaGUKde (ORCPT ); Mon, 21 Jul 2014 06:33:34 -0400 Received: from opensource.wolfsonmicro.com ([80.75.67.52]:43705 "EHLO opensource.wolfsonmicro.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754445AbaGUKdd (ORCPT ); Mon, 21 Jul 2014 06:33:33 -0400 Date: Mon, 21 Jul 2014 11:33:27 +0100 From: Richard Fitzgerald To: Takashi Iwai Cc: Mark Brown , perex@perex.cz, lgirdwood@gmail.com, patches@opensource.wolfsonmicro.com, alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ASoC: arizona: Disable AIF TX/RX before configuring it Message-ID: <20140721103327.GA29141@opensource.wolfsonmicro.com> References: <20140716121029.GA22222@opensource.wolfsonmicro.com> <20140717194215.GH17528@sirena.org.uk> <20140721090104.GA21400@opensource.wolfsonmicro.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 21, 2014 at 11:04:56AM +0200, Takashi Iwai wrote: > At Mon, 21 Jul 2014 10:01:22 +0100, > Richard Fitzgerald wrote: > > > > On Thu, Jul 17, 2014 at 08:42:15PM +0100, Mark Brown wrote: > > > On Wed, Jul 16, 2014 at 01:10:39PM +0100, Richard Fitzgerald wrote: > > > > > > > If we don't disable the AIF TX/RX then we may fall into a > > > > situation where the new AIF settings are ignored by the device. > > > > For example, this problem manifests when switching between > > > > different sample rates. > > > > > > So, what this does is momentarily disable the AIF when reconfiguring. > > > That will glitch any running audio, making me wonder if the driver > > > shouldn't be returning an error or at least complaining if it has to > > > reconfigure instead. What's the use case where this might get > > > triggered? > > > > The case being fixed is like this: > > > > aplay 48kHz.wav; aplay 96kHz.wav > > > > The second open happens before pmdown_time so the AIF is still enabled. > > Writes to the AIF config registers only take effect if the AIF is disabled. > > Without this patch, the 96kHz.wav will play at 48kHz > > If the glitch really matters, the driver can minimize by checking the > change of sample rate and doing temporary turn on/off only when > required. > > > Takashi That's a fair point.