Date: Tue, 28 Apr 2015 15:05:20 +0200
Message-ID: <s5hpp6ov1wv.wl-tiwai@suse.de>
From: Takashi Iwai <tiwai@suse.de>
To: Jonathan McDowell <noodles@earth.li>
Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org
Subject: Re: Audio crackles with 4.1-rc1
In-Reply-To: <20150428123518.GU10148@earth.li>
References: <20150428112156.GQ10148@earth.li>
	<s5hvbggv4xa.wl-tiwai@suse.de>
	<20150428123518.GU10148@earth.li>
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At Tue, 28 Apr 2015 13:35:18 +0100,
Jonathan McDowell wrote:
> 
> On Tue, Apr 28, 2015 at 02:00:17PM +0200, Takashi Iwai wrote:
> > At Tue, 28 Apr 2015 12:21:57 +0100,
> > Jonathan McDowell wrote:
> > > 
> > > Having upgraded to 4.1-rc1 from 4.0 I'm now hearing audio crackles at
> > > regular intervals. I'm fairly sure this is due to the HDA power save as
> > > once audio is playing things are fine, it's just when starting to play
> > > audio that I hear the crackle.
> > > 
> > > System is a Dell Latitude E7240. I haven't tried a bisect yet but will
> > > attempt to find some time to do so in the next few days. It looks like
> > > there have been some changes in sound/hda/ between 4.0 + 4.1-rc1 so I'll
> > > concentrate on those first.
> > > 
> > There are lots of code changes and enhancements wrt power saving in
> > 4.1, and bisection won't help so much, I'm afraid.
> > 
> > First off, check the device status while you hear crackles.
> > Is the codec in runtime suspend (aka power save)?  This can be seen in
> > /sys/bus/hdaudio/devices/*/power/runtime_status.  Then check the
> > runtime status of the controller, too, found in
> > /sys/class/sound/card?/device/power/runtime_status.
> 
> The cracking is definitely happening with the transition from suspended
> to active:
> 
> /sys/class/sound/card0/device/power/runtime_status:suspended
> /sys/class/sound/card1/device/power/runtime_status:active
> /sys/bus/hdaudio/devices/hdaudioC0D0/power/runtime_status:suspended
> /sys/bus/hdaudio/devices/hdaudioC1D0/power/runtime_status:active
> 
> card1 + C1D0 were suspended, I hit delete in a terminal to force a
> terminal bell, got the crackle and the state changed to active as above.

Ah, so it's a click noise that happens only once per runtime PM
transition?  I thought it were constant crackling noises from your
description ("regular intervals").

In anyway, please give alsa-info.sh output on both 4.0 and 4.1.


Takashi
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