From mboxrd@z Thu Jan 1 00:00:00 1970 From: Grazvydas Ignotas Subject: Re: [PATCH -next] ASoC: pandora: Add DAC regulator support Date: Mon, 8 Feb 2010 14:29:17 +0200 Message-ID: <6ed0b2681002080429m6cdc0bc0u98849ae546c7f6e8@mail.gmail.com> References: <1265375612-9079-1-git-send-email-notasas@gmail.com> <1265378923.3177.11.camel@odin> <6ed0b2681002050629p1d38c19m19d1a124ddce307a@mail.gmail.com> <20100205172031.GA31523@rakim.wolfsonmicro.main> <6ed0b2681002060933x38009b77r237db131ab172fee@mail.gmail.com> <20100207110732.9279b77a.jhnikula@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from fg-out-1718.google.com (fg-out-1718.google.com [72.14.220.155]) by alsa0.perex.cz (Postfix) with ESMTP id 7053C243B1 for ; Mon, 8 Feb 2010 13:29:18 +0100 (CET) Received: by fg-out-1718.google.com with SMTP id 22so24826fge.2 for ; Mon, 08 Feb 2010 04:29:17 -0800 (PST) In-Reply-To: <20100207110732.9279b77a.jhnikula@gmail.com> 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: Jarkko Nikula Cc: alsa-devel@alsa-project.org, Mark Brown , Liam Girdwood List-Id: alsa-devel@alsa-project.org On Sun, Feb 7, 2010 at 11:07 AM, Jarkko Nikula wrote: > On Sat, 6 Feb 2010 19:33:08 +0200 > Grazvydas Ignotas wrote: > >> It's on powerdown, there is a faint pop. It appears its the amp (final >> part in the path), I tried to toggle it while playing /dev/zero >> manually and it always pops on powerdown. On powerup there is a small >> sound cutoff too, probably because of amp capacitors charging, but we >> decided to leave it instead of halting every sound playing program >> until the amp gets ready. >> > My side comment for the /dev/zero test. You may hear pops also > if /dev/zero is played as unsigned 8-bit samples on signed DAC since > then samples gets converted to maximum negative value. > > So there is a difference how the /dev/zero is played. First command > below produces a pop because it's playing a pop and second produces a > pop only if HW is producing it. > > aplay /dev/zero > aplay -f S16_LE /dev/zero I was testing with '-f cd' which should also be signed. Actually doing just 'aplay /dev/zero' makes matters worse, there is some additional 'squeek' noise audible when I turn the volume up. On Mon, Feb 8, 2010 at 1:39 PM, Mark Brown wrote: > If this goes off too much you might want to tweak the delay ASoC uses to > defer power down of DAPM widgets after streams stop. There's a command > line option pmdown_time, it really ought to have a sysfs file to tweak > but there's not been any demand. Yes we are already using that (set to 1 minute), and the sysfs file would be useful for us (we have a hack for that in our tree).