linux-kernel - Re: [PATCH v2 2/2] ALSA: usb-audio: Check connector value on resume

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Date:   Thu, 25 Mar 2021 14:41:43 +0100
From:   Takashi Iwai <tiwai@...e.de>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>
Cc:     tiwai@...e.com, Jaroslav Kysela <perex@...ex.cz>,
        Pavel Skripkin <paskripkin@...il.com>,
        Chris Chiu <chiu@...lessm.com>,
        Mark Brown <broonie@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Tom Yan <tom.ty89@...il.com>, Joe Perches <joe@...ches.com>,
        alsa-devel@...a-project.org (moderated list:SOUND),
        linux-kernel@...r.kernel.org (open list)
Subject: Re: [PATCH v2 2/2] ALSA: usb-audio: Check connector value on resume

On Thu, 25 Mar 2021 13:12:48 +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.
> 
> While at it, also remove reset-resume path to consolidate mixer resume
> path.
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> ---
> v2:
>  - Remove reset-resume.
>  - Fold the connector checking to the mixer resume callback.

That's not what I meant exactly...  I meant to put both into the
single resume callback, but handle each part conditionally depending
on reset_resume argument.

But this turned out to need more changes in mixer_quirks.c
unnecessarily.  Maybe adding the two resume functions is a better
approach in the end, but not for the specific connection thing but
generically both resume and reset_resume callbacks.  Something like
below.


thanks,

Takashi


diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index b004b2e63a5d..1dab281bb269 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -3615,20 +3615,43 @@ static int restore_mixer_value(struct usb_mixer_elem_list *list)
 	return 0;
 }
 
+static int default_mixer_resume(struct usb_mixer_elem_list *list)
+{
+	struct usb_mixer_elem_info *cval = mixer_elem_list_to_info(list);
+
+	/* get connector value to "wake up" the USB audio */
+	if (cval->val_type == USB_MIXER_BOOLEAN && cval->channels == 1)
+		get_connector_value(cval, NULL, NULL);
+
+	return 0;
+}
+
+static int default_mixer_reset_resume(struct usb_mixer_elem_list *list)
+{
+	int err = default_mixer_resume(list);
+
+	if (err < 0)
+		return err;
+	return restore_mixer_value(list);
+}
+
 int snd_usb_mixer_resume(struct usb_mixer_interface *mixer, bool reset_resume)
 {
 	struct usb_mixer_elem_list *list;
+	usb_mixer_elem_resume_func_t f;
 	int id, err;
 
-	if (reset_resume) {
-		/* restore cached mixer values */
-		for (id = 0; id < MAX_ID_ELEMS; id++) {
-			for_each_mixer_elem(list, mixer, id) {
-				if (list->resume) {
-					err = list->resume(list);
-					if (err < 0)
-						return err;
-				}
+	/* restore cached mixer values */
+	for (id = 0; id < MAX_ID_ELEMS; id++) {
+		for_each_mixer_elem(list, mixer, id) {
+			if (reset_resume)
+				f = list->reset_resume;
+			else
+				f = list->resume;
+			if (f) {
+				err = list->resume(list);
+				if (err < 0)
+					return err;
 			}
 		}
 	}
@@ -3647,6 +3670,7 @@ void snd_usb_mixer_elem_init_std(struct usb_mixer_elem_list *list,
 	list->id = unitid;
 	list->dump = snd_usb_mixer_dump_cval;
 #ifdef CONFIG_PM
-	list->resume = restore_mixer_value;
+	list->resume = default_mixer_resume;
+	list->reset_resume = default_mixer_reset_resume;
 #endif
 }
diff --git a/sound/usb/mixer.h b/sound/usb/mixer.h
index c29e27ac43a7..e5a01f17bf3c 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 reset_resume;
 };
 
 /* iterate over mixer element list of the given unit id */
diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
index ffd922327ae4..b7f9c2fded05 100644
--- a/sound/usb/mixer_quirks.c
+++ b/sound/usb/mixer_quirks.c
@@ -151,7 +151,7 @@ static int add_single_ctl_with_resume(struct usb_mixer_interface *mixer,
 		*listp = list;
 	list->mixer = mixer;
 	list->id = id;
-	list->resume = resume;
+	list->reset_resume = resume;
 	kctl = snd_ctl_new1(knew, list);
 	if (!kctl) {
 		kfree(list);