linux-kernel - Re: [PATCH] PM: sleep: core: Resume suspended device if direct-complete is disabled

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Message-ID: <s5h35ylxykx.wl-tiwai@suse.de>
Date:   Thu, 28 Jan 2021 09:19:58 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        "Kenneth R . Crudup" <kenny@...ix.com>,
        Pavel Machek <pavel@....cz>, Len Brown <len.brown@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "open list:HIBERNATION (aka Software Suspend, aka swsusp)" 
        <linux-pm@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PM: sleep: core: Resume suspended device if direct-complete is disabled

On Thu, 28 Jan 2021 09:15:10 +0100,
Kai-Heng Feng wrote:
> 
> On Thu, Jan 28, 2021 at 4:09 PM Takashi Iwai <tiwai@...e.de> wrote:
> >
> > On Thu, 31 Dec 2020 07:03:19 +0100,
> > Kai-Heng Feng wrote:
> > >
> > > HDA controller can't be runtime-suspended after commit 215a22ed31a1
> > > ("ALSA: hda: Refactor codjc PM to use direct-complete optimization"),
> > > which enables direct-complete for HDA codec.
> > >
> > > The HDA codec driver doesn't expect direct-complete will be disabled
> > > after it returns a positive value from prepare() callback. So freeze()
> > > is called directly when it's runtime-suspended, breaks the balance of
> > > its internal codec_powered counting.
> > >
> > > So if a device is prepared for direct-complete but PM core breaks the
> > > assumption, resume the device to keep PM operations balanced.
> > >
> > > Fixes: 215a22ed31a1 ("ALSA: hda: Refactor codec PM to use direct-complete optimization")
> > > Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> >
> > Kai-Heng, is this fix still needed for 5.11?
> 
> No it's not needed anymore because "ALSA: hda: Balance runtime/system
> PM if direct-complete is disabled" is in place.
> 
> >
> > The description mentions about HD-audio controller, while the recent
> > revert was the HD-audio codec, so I suppose it's still affected?
> 
> Not affected anymore if above mentioned patch is applied.

OK, thanks for clarification!


Takashi