linux-kernel - Re: [PATCH] [sound] hdac-codec runtime suspended at PM:Suspend.

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Date:   Thu, 15 Mar 2018 16:12:44 +0530
From:   "Subhransu S. Prusty" <subhransu.s.prusty@...el.com>
To:     Anshuman Gupta <anshuman.gupta@...el.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        "moderated list:SOUND - SOC LAYER / DYNAMIC AUDIO POWER MANAGEM..." 
        <alsa-devel@...a-project.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH] [sound] hdac-codec runtime suspended at PM:Suspend.

On Wed, Mar 14, 2018 at 09:07:14PM +0530, Anshuman Gupta wrote:
> On Wed, Mar 14, 2018 at 11:53:58AM +0100, Rafael J. Wysocki wrote:
> > On Wed, Mar 14, 2018 at 11:38 AM, Anshuman Gupta
> > <anshuman.gupta@...el.com> wrote:
> > > On Mon, Mar 12, 2018 at 12:26:53PM +0100, Rafael J. Wysocki wrote:
> > >> On Mon, Mar 12, 2018 at 12:17 PM, Anshuman Gupta
> > >> <anshuman.gupta@...el.com> wrote:
> > >> >
> > >> > +       if (pm_runtime_status_suspended(dev))
> > >> > +               return;
> > >>
> > >> That, again, is somewhat fragile from the concurrency perspective.
> > >>
> > 
> > And here you want to avoid the below if the device is still suspended.
>   Yes, if we do not avoid the code below, complete callback takes about 
>   3 seconds due to snd_hdac_codec_read timed out because hdac controller 
>   would be in runtime suspend state.	
> > 
> > Why is the below code located in the ->complete callback anyway?
> > Shouldn't it be there in the ->resume one?
> > 
>   Yes even i am also having same doubt, why these power down and power up
>   sequences are part of prepare and complete callback.
>   Adding driver author "Subhransu S. Prusty" to provide more inputs on this.

This driver needs a late resume as it receives a jack notification from the
i915 driver and the skl controller driver resume may not have happened and
in turn hda controller may not ready. This ensures a synchronization for
jack event during resume from S3.

I think this patch defeats the purpose.

Regards,
Subhransu

> > >> >         /* Power up afg */
> > >> >         snd_hdac_codec_read(hdac, hdac->afg, 0, AC_VERB_SET_POWER_STATE,
> > >> >                                                         AC_PWRST_D0);
> > >> > --
> > >> > 2.7.4
> 
> -- 
> Thanks,
> Anshuman

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