ALSA: scarlett2: Disable input controls while autogain is running

While the autogain function is running, the other input controls
(select, link, gain, safe, level, air, and phantom) can't be modified.
Update those controls to be read-only during this time.
Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/ad13bacae77860de8c2d7c89f6ec2a1ee104e65f.1703612638.git.g@b4.vu

sound/usb/mixer_scarlett2.c

@@ -2391,6 +2391,30 @@ static int scarlett2_add_sync_ctl(struct usb_mixer_interface *mixer)
 
 /*** Autogain Switch and Status Controls ***/
 
+/* Set the access mode of a control to read-only (val = 0) or
+ * read-write (val = 1).
+ */
+static void scarlett2_set_ctl_access(struct snd_kcontrol *kctl, int val)
+{
+	if (val)
+		kctl->vd[0].access |= SNDRV_CTL_ELEM_ACCESS_WRITE;
+	else
+		kctl->vd[0].access &= ~SNDRV_CTL_ELEM_ACCESS_WRITE;
+}
+
+/* Check if autogain is running on any input */
+static int scarlett2_autogain_is_running(struct scarlett2_data *private)
+{
+	int i;
+
+	for (i = 0; i < private->info->gain_input_count; i++)
+		if (private->autogain_status[i] ==
+		    SCARLETT2_AUTOGAIN_STATUS_RUNNING)
+			return 1;
+
+	return 0;
+}
+
 static int scarlett2_update_autogain(struct usb_mixer_interface *mixer)
 {
 	struct scarlett2_data *private = mixer->private_data;
@@ -2438,13 +2462,108 @@ static int scarlett2_update_autogain(struct usb_mixer_interface *mixer)
 	return 0;
 }
 
+/* Update access mode for controls affected by autogain */
+static void scarlett2_autogain_update_access(struct usb_mixer_interface *mixer)
+{
+	struct scarlett2_data *private = mixer->private_data;
+	const struct scarlett2_device_info *info = private->info;
+	int val = !scarlett2_autogain_is_running(private);
+	int i;
+
+	scarlett2_set_ctl_access(private->input_select_ctl, val);
+	for (i = 0; i < info->gain_input_count / 2; i++)
+		scarlett2_set_ctl_access(private->input_link_ctls[i], val);
+	for (i = 0; i < info->gain_input_count; i++) {
+		scarlett2_set_ctl_access(private->input_gain_ctls[i], val);
+		scarlett2_set_ctl_access(private->safe_ctls[i], val);
+	}
+	for (i = 0; i < info->level_input_count; i++)
+		scarlett2_set_ctl_access(private->level_ctls[i], val);
+	for (i = 0; i < info->air_input_count; i++)
+		scarlett2_set_ctl_access(private->air_ctls[i], val);
+	for (i = 0; i < info->phantom_count; i++)
+		scarlett2_set_ctl_access(private->phantom_ctls[i], val);
+}
+
+/* Notify of access mode change for all controls read-only while
+ * autogain runs.
+ */
+static void scarlett2_autogain_notify_access(struct usb_mixer_interface *mixer)
+{
+	struct snd_card *card = mixer->chip->card;
+	struct scarlett2_data *private = mixer->private_data;
+	const struct scarlett2_device_info *info = private->info;
+	int i;
+
+	snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO,
+		       &private->input_select_ctl->id);
+	for (i = 0; i < info->gain_input_count / 2; i++)
+		snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO,
+			       &private->input_link_ctls[i]->id);
+	for (i = 0; i < info->gain_input_count; i++) {
+		snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO,
+			       &private->input_gain_ctls[i]->id);
+		snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO,
+			       &private->safe_ctls[i]->id);
+	}
+	for (i = 0; i < info->level_input_count; i++)
+		snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO,
+			       &private->level_ctls[i]->id);
+	for (i = 0; i < info->air_input_count; i++)
+		snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO,
+			       &private->air_ctls[i]->id);
+	for (i = 0; i < info->phantom_count; i++)
+		snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_INFO,
+			       &private->phantom_ctls[i]->id);
+}
+
+/* Call scarlett2_update_autogain() and
+ * scarlett2_autogain_update_access() if autogain_updated is set.
+ */
+static int scarlett2_check_autogain_updated(
+	struct usb_mixer_interface *mixer)
+{
+	struct scarlett2_data *private = mixer->private_data;
+	int err;
+
+	if (!private->autogain_updated)
+		return 0;
+
+	err = scarlett2_update_autogain(mixer);
+	if (err < 0)
+		return err;
+
+	scarlett2_autogain_update_access(mixer);
+
+	return 0;
+}
+
+/* If autogain_updated is set when a *_ctl_put() function for a
+ * control that is meant to be read-only while autogain is running,
+ * update the autogain status and access mode of affected controls.
+ * Return -EPERM if autogain is running.
+ */
+static int scarlett2_check_put_during_autogain(
+	struct usb_mixer_interface *mixer)
+{
+	int err = scarlett2_check_autogain_updated(mixer);
+
+	if (err < 0)
+		return err;
+
+	if (scarlett2_autogain_is_running(mixer->private_data))
+		return -EPERM;
+
+	return 0;
+}
+
 static int scarlett2_autogain_switch_ctl_get(
 	struct snd_kcontrol *kctl, struct snd_ctl_elem_value *ucontrol)
 {
 	struct usb_mixer_elem_info *elem = kctl->private_data;
 	struct usb_mixer_interface *mixer = elem->head.mixer;
 	struct scarlett2_data *private = mixer->private_data;
-	int err = 0;
+	int err;
 
 	mutex_lock(&private->data_mutex);
 
@@ -2453,11 +2572,10 @@ static int scarlett2_autogain_switch_ctl_get(
 		goto unlock;
 	}
 
-	if (private->autogain_updated) {
-		err = scarlett2_update_autogain(mixer);
-		if (err < 0)
-			goto unlock;
-	}
+	err = scarlett2_check_autogain_updated(mixer);
+	if (err < 0)
+		goto unlock;
+
 	ucontrol->value.enumerated.item[0] =
 		private->autogain_switch[elem->control];
 
@@ -2472,7 +2590,7 @@ static int scarlett2_autogain_status_ctl_get(
 	struct usb_mixer_elem_info *elem = kctl->private_data;
 	struct usb_mixer_interface *mixer = elem->head.mixer;
 	struct scarlett2_data *private = mixer->private_data;
-	int err = 0;
+	int err;
 
 	mutex_lock(&private->data_mutex);
 
@@ -2481,11 +2599,10 @@ static int scarlett2_autogain_status_ctl_get(
 		goto unlock;
 	}
 
-	if (private->autogain_updated) {
-		err = scarlett2_update_autogain(mixer);
-		if (err < 0)
-			goto unlock;
-	}
+	err = scarlett2_check_autogain_updated(mixer);
+	if (err < 0)
+		goto unlock;
+
 	ucontrol->value.enumerated.item[0] =
 		private->autogain_status[elem->control];
 
@@ -2525,6 +2642,9 @@ static int scarlett2_autogain_switch_ctl_put(
 	if (err == 0)
 		err = 1;
 
+	scarlett2_autogain_update_access(mixer);
+	scarlett2_autogain_notify_access(mixer);
+
 unlock:
 	mutex_unlock(&private->data_mutex);
 	return err;
@@ -2624,7 +2744,7 @@ static int scarlett2_input_select_ctl_put(
 	struct usb_mixer_interface *mixer = elem->head.mixer;
 	struct scarlett2_data *private = mixer->private_data;
 
-	int oval, val, err = 0;
+	int oval, val, err;
 	int max_val = private->input_link_switch[0] ? 0 : 1;
 
 	mutex_lock(&private->data_mutex);
@@ -2634,6 +2754,10 @@ static int scarlett2_input_select_ctl_put(
 		goto unlock;
 	}
 
+	err = scarlett2_check_put_during_autogain(mixer);
+	if (err < 0)
+		goto unlock;
+
 	oval = private->input_select_switch;
 	val = ucontrol->value.integer.value[0];
 
@@ -2677,6 +2801,15 @@ static int scarlett2_input_select_ctl_info(
 
 	mutex_lock(&private->data_mutex);
 
+	if (private->hwdep_in_use) {
+		err = -EBUSY;
+		goto unlock;
+	}
+
+	err = scarlett2_check_autogain_updated(mixer);
+	if (err < 0)
+		goto unlock;
+
 	/* Loop through each input
 	 * Linked inputs have one value for the pair
 	 */
@@ -2694,6 +2827,7 @@ static int scarlett2_input_select_ctl_info(
 	err = snd_ctl_enum_info(uinfo, 1, j,
 				(const char * const *)values);
 
+unlock:
 	mutex_unlock(&private->data_mutex);
 
 	for (i = 0; i < inputs; i++)
@@ -2713,6 +2847,35 @@ static const struct snd_kcontrol_new scarlett2_input_select_ctl = {
 
 /*** Input Link Switch Controls ***/
 
+/* snd_ctl_boolean_mono_info() with autogain-updated check
+ * (for controls that are read-only while autogain is running)
+ */
+static int scarlett2_autogain_disables_ctl_info(struct snd_kcontrol *kctl,
+						struct snd_ctl_elem_info *uinfo)
+{
+	struct usb_mixer_elem_info *elem = kctl->private_data;
+	struct usb_mixer_interface *mixer = elem->head.mixer;
+	struct scarlett2_data *private = mixer->private_data;
+	int err;
+
+	mutex_lock(&private->data_mutex);
+
+	if (private->hwdep_in_use) {
+		err = -EBUSY;
+		goto unlock;
+	}
+
+	err = scarlett2_check_autogain_updated(mixer);
+	if (err < 0)
+		goto unlock;
+
+	err = snd_ctl_boolean_mono_info(kctl, uinfo);
+
+unlock:
+	mutex_unlock(&private->data_mutex);
+	return err;
+}
+
 static int scarlett2_input_link_ctl_get(
 	struct snd_kcontrol *kctl, struct snd_ctl_elem_value *ucontrol)
 {
@@ -2749,7 +2912,7 @@ static int scarlett2_input_link_ctl_put(
 	struct scarlett2_data *private = mixer->private_data;
 
 	int index = elem->control;
-	int oval, val, err = 0;
+	int oval, val, err;
 
 	mutex_lock(&private->data_mutex);
 
@@ -2758,6 +2921,10 @@ static int scarlett2_input_link_ctl_put(
 		goto unlock;
 	}
 
+	err = scarlett2_check_put_during_autogain(mixer);
+	if (err < 0)
+		goto unlock;
+
 	oval = private->input_link_switch[index];
 	val = !!ucontrol->value.integer.value[0];
 
@@ -2789,7 +2956,7 @@ static int scarlett2_input_link_ctl_put(
 static const struct snd_kcontrol_new scarlett2_input_link_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.name = "",
-	.info = snd_ctl_boolean_mono_info,
+	.info = scarlett2_autogain_disables_ctl_info,
 	.get  = scarlett2_input_link_ctl_get,
 	.put  = scarlett2_input_link_ctl_put
 };
@@ -2815,13 +2982,30 @@ static int scarlett2_input_gain_ctl_info(struct snd_kcontrol *kctl,
 					 struct snd_ctl_elem_info *uinfo)
 {
 	struct usb_mixer_elem_info *elem = kctl->private_data;
+	struct usb_mixer_interface *mixer = elem->head.mixer;
+	struct scarlett2_data *private = mixer->private_data;
+	int err;
+
+	mutex_lock(&private->data_mutex);
+
+	if (private->hwdep_in_use) {
+		err = -EBUSY;
+		goto unlock;
+	}
+
+	err = scarlett2_check_autogain_updated(mixer);
+	if (err < 0)
+		goto unlock;
 
 	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
 	uinfo->count = elem->channels;
 	uinfo->value.integer.min = 0;
 	uinfo->value.integer.max = SCARLETT2_GAIN_BIAS;
 	uinfo->value.integer.step = 1;
-	return 0;
+
+unlock:
+	mutex_unlock(&private->data_mutex);
+	return err;
 }
 
 static int scarlett2_input_gain_ctl_get(struct snd_kcontrol *kctl,
@@ -2860,7 +3044,7 @@ static int scarlett2_input_gain_ctl_put(struct snd_kcontrol *kctl,
 	struct scarlett2_data *private = mixer->private_data;
 
 	int index = elem->control;
-	int oval, val, err = 0;
+	int oval, val, err;
 
 	mutex_lock(&private->data_mutex);
 
@@ -2869,6 +3053,10 @@ static int scarlett2_input_gain_ctl_put(struct snd_kcontrol *kctl,
 		goto unlock;
 	}
 
+	err = scarlett2_check_put_during_autogain(mixer);
+	if (err < 0)
+		goto unlock;
+
 	oval = private->gain[index];
 	val = ucontrol->value.integer.value[0];
 
@@ -2957,7 +3145,7 @@ static int scarlett2_safe_ctl_put(struct snd_kcontrol *kctl,
 	struct scarlett2_data *private = mixer->private_data;
 
 	int index = elem->control;
-	int oval, val, err = 0;
+	int oval, val, err;
 
 	mutex_lock(&private->data_mutex);
 
@@ -2966,6 +3154,10 @@ static int scarlett2_safe_ctl_put(struct snd_kcontrol *kctl,
 		goto unlock;
 	}
 
+	err = scarlett2_check_put_during_autogain(mixer);
+	if (err < 0)
+		goto unlock;
+
 	oval = private->safe_switch[index];
 	val = !!ucontrol->value.integer.value[0];
 
@@ -2988,7 +3180,7 @@ static int scarlett2_safe_ctl_put(struct snd_kcontrol *kctl,
 static const struct snd_kcontrol_new scarlett2_safe_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.name = "",
-	.info = snd_ctl_boolean_mono_info,
+	.info = scarlett2_autogain_disables_ctl_info,
 	.get  = scarlett2_safe_ctl_get,
 	.put  = scarlett2_safe_ctl_put,
 };
@@ -3434,8 +3626,27 @@ static int scarlett2_level_enum_ctl_info(struct snd_kcontrol *kctl,
 	static const char *const values[2] = {
 		"Line", "Inst"
 	};
+	struct usb_mixer_elem_info *elem = kctl->private_data;
+	struct usb_mixer_interface *mixer = elem->head.mixer;
+	struct scarlett2_data *private = mixer->private_data;
+	int err;
 
-	return snd_ctl_enum_info(uinfo, 1, 2, values);
+	mutex_lock(&private->data_mutex);
+
+	if (private->hwdep_in_use) {
+		err = -EBUSY;
+		goto unlock;
+	}
+
+	err = scarlett2_check_autogain_updated(mixer);
+	if (err < 0)
+		goto unlock;
+
+	err = snd_ctl_enum_info(uinfo, 1, 2, values);
+
+unlock:
+	mutex_unlock(&private->data_mutex);
+	return err;
 }
 
 static int scarlett2_level_enum_ctl_get(struct snd_kcontrol *kctl,
@@ -3478,7 +3689,7 @@ static int scarlett2_level_enum_ctl_put(struct snd_kcontrol *kctl,
 	const struct scarlett2_device_info *info = private->info;
 
 	int index = elem->control + info->level_input_first;
-	int oval, val, err = 0;
+	int oval, val, err;
 
 	mutex_lock(&private->data_mutex);
 
@@ -3487,6 +3698,10 @@ static int scarlett2_level_enum_ctl_put(struct snd_kcontrol *kctl,
 		goto unlock;
 	}
 
+	err = scarlett2_check_put_during_autogain(mixer);
+	if (err < 0)
+		goto unlock;
+
 	oval = private->level_switch[index];
 	val = !!ucontrol->value.enumerated.item[0];
 
@@ -3659,7 +3874,7 @@ static int scarlett2_air_ctl_put(struct snd_kcontrol *kctl,
 	struct scarlett2_data *private = mixer->private_data;
 
 	int index = elem->control;
-	int oval, val, err = 0;
+	int oval, val, err;
 
 	mutex_lock(&private->data_mutex);
 
@@ -3668,6 +3883,10 @@ static int scarlett2_air_ctl_put(struct snd_kcontrol *kctl,
 		goto unlock;
 	}
 
+	err = scarlett2_check_put_during_autogain(mixer);
+	if (err < 0)
+		goto unlock;
+
 	oval = private->air_switch[index];
 	val = ucontrol->value.integer.value[0];
 
@@ -3693,8 +3912,27 @@ static int scarlett2_air_with_drive_ctl_info(
 	static const char *const values[3] = {
 		"Off", "Presence", "Presence + Drive"
 	};
+	struct usb_mixer_elem_info *elem = kctl->private_data;
+	struct usb_mixer_interface *mixer = elem->head.mixer;
+	struct scarlett2_data *private = mixer->private_data;
+	int err;
 
-	return snd_ctl_enum_info(uinfo, 1, 3, values);
+	mutex_lock(&private->data_mutex);
+
+	if (private->hwdep_in_use) {
+		err = -EBUSY;
+		goto unlock;
+	}
+
+	err = scarlett2_check_autogain_updated(mixer);
+	if (err < 0)
+		goto unlock;
+
+	err = snd_ctl_enum_info(uinfo, 1, 3, values);
+
+unlock:
+	mutex_unlock(&private->data_mutex);
+	return err;
 }
 
 static const struct snd_kcontrol_new scarlett2_air_ctl[2] = {
@@ -3782,7 +4020,7 @@ static int scarlett2_phantom_ctl_put(struct snd_kcontrol *kctl,
 	const struct scarlett2_device_info *info = private->info;
 
 	int index = elem->control;
-	int oval, val, err = 0;
+	int oval, val, err;
 
 	mutex_lock(&private->data_mutex);
 
@@ -3791,6 +4029,10 @@ static int scarlett2_phantom_ctl_put(struct snd_kcontrol *kctl,
 		goto unlock;
 	}
 
+	err = scarlett2_check_put_during_autogain(mixer);
+	if (err < 0)
+		goto unlock;
+
 	oval = private->phantom_switch[index];
 	val = !!ucontrol->value.integer.value[0];
 
@@ -3817,7 +4059,7 @@ static int scarlett2_phantom_ctl_put(struct snd_kcontrol *kctl,
 static const struct snd_kcontrol_new scarlett2_phantom_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.name = "",
-	.info = snd_ctl_boolean_mono_info,
+	.info = scarlett2_autogain_disables_ctl_info,
 	.get  = scarlett2_phantom_ctl_get,
 	.put  = scarlett2_phantom_ctl_put,
 };
@@ -5743,6 +5985,8 @@ static __always_unused void scarlett2_notify_autogain(
 		snd_ctl_notify(card, SNDRV_CTL_EVENT_MASK_VALUE,
 			       &private->autogain_status_ctls[i]->id);
 	}
+
+	scarlett2_autogain_notify_access(mixer);
 }
 
 /* Notify on input safe switch change */
@@ -5987,6 +6231,10 @@ static int snd_scarlett2_controls_create(
 	if (err < 0)
 		return err;
 
+	/* Set the access mode of controls disabled during autogain */
+	if (private->info->gain_input_count)
+		scarlett2_autogain_update_access(mixer);
+
 	/* Set up the interrupt polling */
 	err = scarlett2_init_notify(mixer);
 	if (err < 0)