linux-kernel - Re: [PATCH] sound: usb: pcm: fix incorrect power state when playing sound after PM

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Date:   Wed, 03 Jun 2020 10:45:41 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     Macpaul Lin <macpaul.lin@...iatek.com>
Cc:     Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Alexander Tsoy <alexander@...y.me>,
        Johan Hovold <johan@...nel.org>,
        Hui Wang <hui.wang@...onical.com>,
        Szabolcs Szőke <szszoke.code@...il.com>,
        <alsa-devel@...a-project.org>, <linux-usb@...r.kernel.org>,
        Mediatek WSD Upstream <wsd_upstream@...iatek.com>,
        Macpaul Lin <macpaul.lin@...il.com>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] sound: usb: pcm: fix incorrect power state when playing sound after PM_AUTO suspend

On Wed, 03 Jun 2020 08:54:51 +0200,
Takashi Iwai wrote:
> 
> On Wed, 03 Jun 2020 08:28:09 +0200,
> Takashi Iwai wrote:
> > 
> > And, the most suspicious case is the last one,
> > chip->num_suspended-intf.  It means that the device has multiple
> > USB interfaces and they went to suspend, while the resume isn't
> > performed for the all suspended interfaces in return.
> 
> If this is the cause, a patch like below might help.
> It gets/puts the all assigned interfaced instead of only the primary
> one.

... and considering of the problem again, rather the patch below might
be the right answer.  Now the driver tries to remember at which state
it entered into the system-suspend.  Upon resume, in return, when the
state reaches back to that point, set the card state to D0.

The previous patch can be applied on the top, too, and it might be
worth to apply both.

Let me know if any of those actually helps.


Takashi

---
diff --git a/sound/usb/card.c b/sound/usb/card.c
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -843,9 +843,6 @@ static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message)
 	if (chip == (void *)-1L)
 		return 0;
 
-	chip->autosuspended = !!PMSG_IS_AUTO(message);
-	if (!chip->autosuspended)
-		snd_power_change_state(chip->card, SNDRV_CTL_POWER_D3hot);
 	if (!chip->num_suspended_intf++) {
 		list_for_each_entry(as, &chip->pcm_list, list) {
 			snd_usb_pcm_suspend(as);
@@ -858,6 +855,11 @@ static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message)
 			snd_usb_mixer_suspend(mixer);
 	}
 
+	if (!PMSG_IS_AUTO(message) && !chip->system_suspend) {
+		snd_power_change_state(chip->card, SNDRV_CTL_POWER_D3hot);
+		chip->system_suspend = chip->num_suspended_intf;
+	}
+
 	return 0;
 }
 
@@ -871,10 +873,10 @@ static int __usb_audio_resume(struct usb_interface *intf, bool reset_resume)
 
 	if (chip == (void *)-1L)
 		return 0;
-	if (--chip->num_suspended_intf)
-		return 0;
 
 	atomic_inc(&chip->active); /* avoid autopm */
+	if (chip->num_suspended_intf > 1)
+		goto out;
 
 	list_for_each_entry(as, &chip->pcm_list, list) {
 		err = snd_usb_pcm_resume(as);
@@ -896,9 +898,12 @@ static int __usb_audio_resume(struct usb_interface *intf, bool reset_resume)
 		snd_usbmidi_resume(p);
 	}
 
-	if (!chip->autosuspended)
+ out:
+	if (chip->num_suspended_intf == chip->system_suspend) {
 		snd_power_change_state(chip->card, SNDRV_CTL_POWER_D0);
-	chip->autosuspended = 0;
+		chip->system_suspend = 0;
+	}
+	chip->num_suspended_intf--;
 
 err_out:
 	atomic_dec(&chip->active); /* allow autopm after this point */
diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index 1c892c7f14d7..e0ebfb25fbd5 100644
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -26,7 +26,7 @@ struct snd_usb_audio {
 	struct usb_interface *pm_intf;
 	u32 usb_id;
 	struct mutex mutex;
-	unsigned int autosuspended:1;	
+	unsigned int system_suspend;
 	atomic_t active;
 	atomic_t shutdown;
 	atomic_t usage_count;