ALSA: scarlett2: Add R/O headphone volume control

The Scarlett 4i4 Gen 4 adds a R/O headphone volume control in addition
to a R/O master volume control (which is already supported).

Mark the new scarlett2_notify_volume() function with __always_unused
until it gets used when the Gen 4 notification callback function arrays
are added.

Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/bd4a76da157f8cc3fbfa02eba96d02bdb86817c5.1703612638.git.g@b4.vu

diff --git a/sound/usb/mixer_scarlett2.c b/sound/usb/mixer_scarlett2.c
index f1c9f6b022ce51d5a70077bfec392aa2a56b1b34..94413fca2b6c826fd3919f349cea077cc143097e 100644 (file)
--- a/sound/usb/mixer_scarlett2.c
+++ b/sound/usb/mixer_scarlett2.c
@@ -332,6 +332,7 @@ enum {
        SCARLETT2_CONFIG_MUTE_SWITCH,
        SCARLETT2_CONFIG_SW_HW_SWITCH,
        SCARLETT2_CONFIG_MASTER_VOLUME,
+       SCARLETT2_CONFIG_HEADPHONE_VOLUME,
        SCARLETT2_CONFIG_LEVEL_SWITCH,
        SCARLETT2_CONFIG_PAD_SWITCH,
        SCARLETT2_CONFIG_MSD_SWITCH,
@@ -784,6 +785,7 @@ struct scarlett2_data {
        u8 power_status_updated;
        u8 sync;
        u8 master_vol;
+       u8 headphone_vol;
        u8 vol[SCARLETT2_ANALOGUE_MAX];
        u8 vol_sw_hw_switch[SCARLETT2_ANALOGUE_MAX];
        u8 mute_switch[SCARLETT2_ANALOGUE_MAX];
@@ -809,6 +811,7 @@ struct scarlett2_data {
        u8 meter_level_map[SCARLETT2_MAX_METERS];
        struct snd_kcontrol *sync_ctl;
        struct snd_kcontrol *master_vol_ctl;
+       struct snd_kcontrol *headphone_vol_ctl;
        struct snd_kcontrol *vol_ctls[SCARLETT2_ANALOGUE_MAX];
        struct snd_kcontrol *sw_hw_ctls[SCARLETT2_ANALOGUE_MAX];
        struct snd_kcontrol *mute_ctls[SCARLETT2_ANALOGUE_MAX];
@@ -3324,6 +3327,18 @@ static int scarlett2_update_volumes(struct usb_mixer_interface *mixer)
                                        private->vol[i] = private->master_vol;
        }
 
+       if (scarlett2_has_config_item(private,
+                                     SCARLETT2_CONFIG_HEADPHONE_VOLUME)) {
+               err = scarlett2_usb_get_config(
+                       mixer, SCARLETT2_CONFIG_HEADPHONE_VOLUME,
+                       1, &vol);
+               if (err < 0)
+                       return err;
+
+               private->headphone_vol = clamp(vol + SCARLETT2_VOLUME_BIAS,
+                                              0, SCARLETT2_VOLUME_BIAS);
+       }
+
        return 0;
 }
 
@@ -3367,6 +3382,34 @@ unlock:
        return err;
 }
 
+static int scarlett2_headphone_volume_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;
+
+       mutex_lock(&private->data_mutex);
+
+       if (private->hwdep_in_use) {
+               err = -EBUSY;
+               goto unlock;
+       }
+
+       if (private->vol_updated) {
+               err = scarlett2_update_volumes(mixer);
+               if (err < 0)
+                       goto unlock;
+       }
+       ucontrol->value.integer.value[0] = private->headphone_vol;
+
+unlock:
+       mutex_unlock(&private->data_mutex);
+       return err;
+}
+
 static int line_out_remap(struct scarlett2_data *private, int index)
 {
        const struct scarlett2_device_info *info = private->info;
@@ -3456,6 +3499,17 @@ static const struct snd_kcontrol_new scarlett2_master_volume_ctl = {
        .tlv = { .p = db_scale_scarlett2_volume }
 };
 
+static const struct snd_kcontrol_new scarlett2_headphone_volume_ctl = {
+       .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
+       .access = SNDRV_CTL_ELEM_ACCESS_READ |
+                 SNDRV_CTL_ELEM_ACCESS_TLV_READ,
+       .name = "",
+       .info = scarlett2_volume_ctl_info,
+       .get  = scarlett2_headphone_volume_ctl_get,
+       .private_value = 0, /* max value */
+       .tlv = { .p = db_scale_scarlett2_volume }
+};
+
 static const struct snd_kcontrol_new scarlett2_line_out_volume_ctl = {
        .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
        .access = SNDRV_CTL_ELEM_ACCESS_READWRITE |
@@ -4806,6 +4860,18 @@ static int scarlett2_add_line_out_ctls(struct usb_mixer_interface *mixer)
                        return err;
        }
 
+       /* Add R/O headphone volume control */
+       if (scarlett2_has_config_item(private,
+                                     SCARLETT2_CONFIG_HEADPHONE_VOLUME)) {
+               snprintf(s, sizeof(s), "Headphone Playback Volume");
+               err = scarlett2_add_new_ctl(mixer,
+                                           &scarlett2_headphone_volume_ctl,
+                                           0, 1, s,
+                                           &private->headphone_vol_ctl);
+               if (err < 0)
+                       return err;
+       }
+
        /* Remaining controls are only applicable if the device
         * has per-channel line-out volume controls.
         */
@@ -6265,7 +6331,7 @@ static void scarlett2_notify_sync(struct usb_mixer_interface *mixer)
                       &private->sync_ctl->id);
 }
 
-/* Notify on monitor change */
+/* Notify on monitor change (Gen 2/3) */
 static void scarlett2_notify_monitor(struct usb_mixer_interface *mixer)
 {
        struct snd_card *card = mixer->chip->card;
@@ -6286,6 +6352,20 @@ static void scarlett2_notify_monitor(struct usb_mixer_interface *mixer)
                                       &private->vol_ctls[i]->id);
 }
 
+/* Notify on volume change (Gen 4) */
+static __always_unused void scarlett2_notify_volume(
+       struct usb_mixer_interface *mixer)
+{
+       struct scarlett2_data *private = mixer->private_data;
+
+       private->vol_updated = 1;
+
+       snd_ctl_notify(mixer->chip->card, SNDRV_CTL_EVENT_MASK_VALUE,
+                      &private->master_vol_ctl->id);
+       snd_ctl_notify(mixer->chip->card, SNDRV_CTL_EVENT_MASK_VALUE,
+                      &private->headphone_vol_ctl->id);
+}
+
 /* Notify on dim/mute change */
 static void scarlett2_notify_dim_mute(struct usb_mixer_interface *mixer)
 {