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 08:54:51 +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 08:28:09 +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.


Takashi

---
diff --git a/sound/usb/card.c b/sound/usb/card.c
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -634,7 +634,6 @@ static int usb_audio_probe(struct usb_interface *intf,
 								   id, &chip);
 					if (err < 0)
 						goto __error;
-					chip->pm_intf = intf;
 					break;
 				} else if (vid[i] != -1 || pid[i] != -1) {
 					dev_info(&dev->dev,
@@ -651,6 +650,13 @@ static int usb_audio_probe(struct usb_interface *intf,
 			goto __error;
 		}
 	}
+
+	if (chip->num_interfaces >= MAX_CARD_INTERFACES) {
+		dev_info(&dev->dev, "Too many interfaces assigned to the single USB-audio card\n");
+		err = -EINVAL;
+		goto __error;
+	}
+
 	dev_set_drvdata(&dev->dev, chip);
 
 	/*
@@ -703,6 +709,7 @@ static int usb_audio_probe(struct usb_interface *intf,
 	}
 
 	usb_chip[chip->index] = chip;
+	chip->intf[chip->num_interfaces] = intf;
 	chip->num_interfaces++;
 	usb_set_intfdata(intf, chip);
 	atomic_dec(&chip->active);
@@ -818,19 +825,36 @@ void snd_usb_unlock_shutdown(struct snd_usb_audio *chip)
 
 int snd_usb_autoresume(struct snd_usb_audio *chip)
 {
+	int i, err;
+
 	if (atomic_read(&chip->shutdown))
 		return -EIO;
-	if (atomic_inc_return(&chip->active) == 1)
-		return usb_autopm_get_interface(chip->pm_intf);
+	if (atomic_inc_return(&chip->active) != 1)
+		return 0;
+
+	for (i = 0; i < chip->num_interfaces; i++) {
+		err = usb_autopm_get_interface(chip->intf[i]);
+		if (err < 0) {
+			/* rollback */
+			while (--i >= 0)
+				usb_autopm_put_interface(chip->intf[i]);
+			return err;
+		}
+	}
 	return 0;
 }
 
 void snd_usb_autosuspend(struct snd_usb_audio *chip)
 {
+	int i;
+
 	if (atomic_read(&chip->shutdown))
 		return;
-	if (atomic_dec_and_test(&chip->active))
-		usb_autopm_put_interface(chip->pm_intf);
+	if (!atomic_dec_and_test(&chip->active))
+		return;
+
+	for (i = 0; i < chip->num_interfaces; i++)
+		usb_autopm_put_interface(chip->intf[i]);
 }
 
 static int usb_audio_suspend(struct usb_interface *intf, pm_message_t message)
diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
--- a/sound/usb/usbaudio.h
+++ b/sound/usb/usbaudio.h
@@ -19,11 +19,13 @@
 struct media_device;
 struct media_intf_devnode;
 
+#define MAX_CARD_INTERFACES	16
+
 struct snd_usb_audio {
 	int index;
 	struct usb_device *dev;
 	struct snd_card *card;
-	struct usb_interface *pm_intf;
+	struct usb_interface *intf[MAX_CARD_INTERFACES];
 	u32 usb_id;
 	struct mutex mutex;
 	unsigned int autosuspended:1;