ALSA: usb-audio: scarlett2: Fix Level Meter control

The Level Meter control had a fixed number of channels and therefore
only worked with the 18i20 Gen 2. Fix the control to contain the
correct number of channels.

Signed-off-by: Geoffrey D. Bennett <g@b4.vu>
Link: https://lore.kernel.org/r/5e9a2d5c136270db2d048db53a3b4b6e6d4a63de.1624294591.git.g@b4.vu
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/mixer_scarlett_gen2.c b/sound/usb/mixer_scarlett_gen2.c
index 7647b342809386dad4dfa54e8a487a1f9391ca75..dde008ea21d78f4f02509fbf5a4320c9874228fd 100644 (file)
--- a/sound/usb/mixer_scarlett_gen2.c
+++ b/sound/usb/mixer_scarlett_gen2.c
@@ -161,10 +161,8 @@ static const u16 scarlett2_mixer_values[SCARLETT2_MIXER_VALUE_COUNT] = {
  */
 #define SCARLETT2_MUX_MAX 64
 
-/* Number of meters:
- * 18 inputs, 20 outputs, 18 matrix inputs
- */
-#define SCARLETT2_NUM_METERS 56
+/* Maximum number of meters (sum of output port counts) */
+#define SCARLETT2_MAX_METERS 56
 
 /* Hardware port types:
  * - None (no input to mux)
@@ -1097,26 +1095,26 @@ static int scarlett2_usb_set_mux(struct usb_mixer_interface *mixer)
 
 /* Send USB message to get meter levels */
 static int scarlett2_usb_get_meter_levels(struct usb_mixer_interface *mixer,
-                                         u16 *levels)
+                                         u16 num_meters, u16 *levels)
 {
        struct {
                __le16 pad;
                __le16 num_meters;
                __le32 magic;
        } __packed req;
-       u32 resp[SCARLETT2_NUM_METERS];
+       u32 resp[SCARLETT2_MAX_METERS];
        int i, err;
 
        req.pad = 0;
-       req.num_meters = cpu_to_le16(SCARLETT2_NUM_METERS);
+       req.num_meters = cpu_to_le16(num_meters);
        req.magic = cpu_to_le32(SCARLETT2_USB_METER_LEVELS_GET_MAGIC);
        err = scarlett2_usb(mixer, SCARLETT2_USB_GET_METER,
-                           &req, sizeof(req), resp, sizeof(resp));
+                           &req, sizeof(req), resp, num_meters * sizeof(u32));
        if (err < 0)
                return err;
 
        /* copy, convert to u16 */
-       for (i = 0; i < SCARLETT2_NUM_METERS; i++)
+       for (i = 0; i < num_meters; i++)
                levels[i] = resp[i];
 
        return 0;
@@ -2053,10 +2051,11 @@ static int scarlett2_meter_ctl_get(struct snd_kcontrol *kctl,
                                   struct snd_ctl_elem_value *ucontrol)
 {
        struct usb_mixer_elem_info *elem = kctl->private_data;
-       u16 meter_levels[SCARLETT2_NUM_METERS];
+       u16 meter_levels[SCARLETT2_MAX_METERS];
        int i, err;
 
-       err = scarlett2_usb_get_meter_levels(elem->head.mixer, meter_levels);
+       err = scarlett2_usb_get_meter_levels(elem->head.mixer, elem->channels,
+                                            meter_levels);
        if (err < 0)
                return err;
 
@@ -2076,8 +2075,10 @@ static const struct snd_kcontrol_new scarlett2_meter_ctl = {
 
 static int scarlett2_add_meter_ctl(struct usb_mixer_interface *mixer)
 {
+       struct scarlett2_data *private = mixer->private_data;
+
        return scarlett2_add_new_ctl(mixer, &scarlett2_meter_ctl,
-                                    0, SCARLETT2_NUM_METERS,
+                                    0, private->num_mux_dsts,
                                     "Level Meter", NULL);
 }