linux-kernel - Re: [PATCH 2/2] ALSA: usb-audio: Check connector value on resume

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Date:   Thu, 25 Mar 2021 15:26:09 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     Takashi Iwai <tiwai@...e.com>, Jaroslav Kysela <perex@...ex.cz>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Chris Chiu <chiu@...lessm.com>, Joe Perches <joe@...ches.com>,
        Tom Yan <tom.ty89@...il.com>,
        "moderated list:SOUND" <alsa-devel@...a-project.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] ALSA: usb-audio: Check connector value on resume

On Thu, Mar 25, 2021 at 3:19 PM Takashi Iwai <tiwai@...e.de> wrote:
>
> On Wed, 24 Mar 2021 18:14:08 +0100,
> Kai-Heng Feng wrote:
> >
> > Rear Mic on Lenovo P620 cannot record after S3, despite that there's no
> > error and the other two functions of the USB audio, Line In and Line
> > Out, work just fine.
> >
> > The mic starts to work again after running userspace app like "alsactl
> > store". Following the lead, the evidence shows that as soon as connector
> > status is queried, the mic can work again.
> >
> > So also check connector value on resume to "wake up" the USB audio to
> > make it functional.
> >
> > This can be device specific, however I think this generic approach may
> > benefit more than one device.
> >
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
>
> Just to be sure: this workaround is always needed no matter whether
> reset_resume is set or not?

Yes, reset_resume is irrelevant for this issue. Getting connector
status is the key.

> If so, it's better to change the resume
> callback to take reset_resume argument and call it always.  The
> resume_connector() can be folded into there.

OK, will send V2.

Kai-Heng

>
>
> thanks,
>
> Takashi
>
> > ---
> >  sound/usb/mixer.c | 18 ++++++++++++++++++
> >  sound/usb/mixer.h |  1 +
> >  2 files changed, 19 insertions(+)
> >
> > diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> > index 98f5417a70e4..6a553d891b0f 100644
> > --- a/sound/usb/mixer.c
> > +++ b/sound/usb/mixer.c
> > @@ -3631,11 +3631,28 @@ static int restore_mixer_value(struct usb_mixer_elem_list *list)
> >       return 0;
> >  }
> >
> > +static int resume_connector(struct usb_mixer_elem_list *list)
> > +{
> > +     struct usb_mixer_elem_info *cval = mixer_elem_list_to_info(list);
> > +
> > +     if (cval->val_type != USB_MIXER_BOOLEAN || cval->channels != 1)
> > +             return 0;
> > +
> > +     return get_connector_value(cval, NULL, NULL);
> > +}
> > +
> >  int snd_usb_mixer_resume(struct usb_mixer_interface *mixer, bool reset_resume)
> >  {
> >       struct usb_mixer_elem_list *list;
> >       int id, err;
> >
> > +     for (id = 0; id < MAX_ID_ELEMS; id++) {
> > +             for_each_mixer_elem(list, mixer, id) {
> > +                     if (list->resume_connector)
> > +                             list->resume_connector(list);
> > +             }
> > +     }
> > +
> >       if (reset_resume) {
> >               /* restore cached mixer values */
> >               for (id = 0; id < MAX_ID_ELEMS; id++) {
> > @@ -3664,5 +3681,6 @@ void snd_usb_mixer_elem_init_std(struct usb_mixer_elem_list *list,
> >       list->dump = snd_usb_mixer_dump_cval;
> >  #ifdef CONFIG_PM
> >       list->resume = restore_mixer_value;
> > +     list->resume_connector = resume_connector;
> >  #endif
> >  }
> > diff --git a/sound/usb/mixer.h b/sound/usb/mixer.h
> > index c29e27ac43a7..843ccff0eea3 100644
> > --- a/sound/usb/mixer.h
> > +++ b/sound/usb/mixer.h
> > @@ -69,6 +69,7 @@ struct usb_mixer_elem_list {
> >       bool is_std_info;
> >       usb_mixer_elem_dump_func_t dump;
> >       usb_mixer_elem_resume_func_t resume;
> > +     usb_mixer_elem_resume_func_t resume_connector;
> >  };
> >
> >  /* iterate over mixer element list of the given unit id */
> > --
> > 2.30.2
> >