From mboxrd@z Thu Jan 1 00:00:00 1970 From: Takashi Iwai Subject: Re: [PATCH] ALSA: ca0106: Disable IZD on SB0570 DAC to fix audio pops Date: Mon, 29 Oct 2018 16:59:25 +0100 Message-ID: References: <20181028165512.24474-1-alex@astanoev.com> Mime-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by alsa0.perex.cz (Postfix) with ESMTP id B4F212675C0 for ; Mon, 29 Oct 2018 16:59:26 +0100 (CET) In-Reply-To: <20181028165512.24474-1-alex@astanoev.com> 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: Alex Stanoev Cc: alsa-devel@alsa-project.org List-Id: alsa-devel@alsa-project.org On Sun, 28 Oct 2018 17:55:12 +0100, Alex Stanoev wrote: > > The Creative Audigy SE (SB0570) card currently exhibits an audible pop > whenever playback is stopped or resumed, or during silent periods of an > audio stream. Initialise the IZD bit to the 0 to eliminate these pops. > > The Infinite Zero Detection (IZD) feature on the DAC causes the output > to be shunted to Vcap after 2048 samples of silence. This discharges the > AC coupling capacitor through the output and causes the aforementioned > pop/click noise. > > The behaviour of the IZD bit is described on page 15 of the WM8768GEDS > datasheet: "With IZD=1, applying MUTE for 1024 consecutive input samples > will cause all outputs to be connected directly to VCAP. This also > happens if 2048 consecutive zero input samples are applied to all 6 > channels, and IZD=0. It will be removed as soon as any channel receives > a non-zero input". I believe the second sentence might be referring to > IZD=1 instead of IZD=0 given the observed behaviour of the card. > > This change should make the DAC initialisation consistent with > Creative's Windows driver, as this popping persists when initialising > the card in Linux and soft rebooting into Windows, but is not present on > a cold boot to Windows. > > Signed-off-by: Alex Stanoev Applied (with Cc to stable) now. Thanks. Takashi