linux-kernel - Re: Powersave doesn't work for snd_hda

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Message-ID: <s5hei32vzby.wl%tiwai@suse.de>
Date:	Fri, 10 Jun 2011 10:57:05 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	Michal Hocko <mhocko@...e.cz>
Cc:	LKML <linux-kernel@...r.kernel.org>, alsa-devel@...a-project.org
Subject: Re: Powersave doesn't work for snd_hda_intel with 3.0.0-rc2

At Fri, 10 Jun 2011 10:39:56 +0200,
Michal Hocko wrote:
> 
> [changed subject]
> 
> As a summary:
> I am loosing sound after powe_save timeout expires if there is no device
> activity. The only way how to get sound back is to unload the module and
> load it again.
> 
> On Fri 10-06-11 10:17:09, Takashi Iwai wrote:
> > At Fri, 10 Jun 2011 09:56:40 +0200,
> > Michal Hocko wrote:
> > > > 
> > > > Note that the one-minute thing happens only when you unplug AC cable,
> > > > supposedly.  
> > > 
> > > Hmmm, I was plugged during testing all the time. OK, this looks like a
> > > separate issue. I will repost it as a separate thread once we are done
> > > with this. Any idea who to CC?
> > 
> > First off, check /sys/modules/snd_hda_intel/parameters/powersave
> > value.  If this is set to non-zero, someone must have played with it,
> > e.g. pm-utils or such.
> 
> Yes, it contains 60. And the value comes from:
> CONFIG_SND_HDA_POWER_SAVE_DEFAULT=60
> 
> which defaults to 0 so it must have been changed by me some time ago
> (really do not remember when and why, though). Anyway I have the same
> value in 2.6.39 kernel as well and I do not see any problem there.
> So it looks like a regression.

Interestingly, I see power_save=0 value in some of your alsa-info.sh
outputs.   That is, something changed it to 0 dynamically even though
you set to 60 as default.  (I thought it was set to 60 by daemon, but
in reality, it was reverted -- it was clear to 0 dynamically.)

It might be just coincidence that the older kernel didn't show the
problem.  It might have power_save=0 set dynamically without
noticing...


thanks,

Takashi
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