ALSA: scarlett2: Remap Level Meter values

The values previously returned by the Level Meter control were passed
through from the interface without interpretation, but it has been
discovered that the order of the values matches the mux assignment
order (which is not presented to userspace). In addition, the values
for disabled mux outputs, and mux outputs which share a source are
invalid.

This patch adds a per-device meter_map[], and a dynamic
meter_level_map[] which is updated on routing changes. The meter level
map gets used by scarlett2_meter_ctl_get() to both present the values
in a standard order, and to fix up the invalid values by zeroing them
(for disabled outputs) and copying them (for mux outputs which share a
source).

Signed-off-by: Geoffrey D. Bennett <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>

Author: geoffreybennett

sound/usb/mixer_scarlett2.c

@@ -210,6 +210,9 @@ static const u16 scarlett2_mixer_values[SCARLETT2_MIXER_VALUE_COUNT] = {
  */
 #define SCARLETT2_MUX_MAX 77
 
+/* Maximum number of sources (sum of input port counts) */
+#define SCARLETT2_MAX_SRCS 52
+
 /* Maximum number of meters (sum of output port counts) */
 #define SCARLETT2_MAX_METERS 65
 
@@ -328,6 +331,18 @@ struct scarlett2_mux_entry {
 	u8 count;
 };
 
+/* Maximum number of entries in a mux table */
+#define SCARLETT2_MAX_METER_ENTRIES 9
+
+/* One entry within meter_assignment defines the range of mux outputs
+ * that consecutive meter entries are mapped to. The end of the list
+ * is marked with count == 0.
+ */
+struct scarlett2_meter_entry {
+	u8 start;
+	u8 count;
+};
+
 struct scarlett2_device_info {
 	/* Gen 3 devices have an internal MSD mode switch that needs
 	 * to be disabled in order to access the full functionality of
@@ -381,6 +396,7 @@ struct scarlett2_device_info {
 	 */
 	u8 line_out_remap_enable;
 	u8 line_out_remap[SCARLETT2_ANALOGUE_MAX];
+	u8 line_out_unmap[SCARLETT2_ANALOGUE_MAX];
 
 	/* additional description for the line out volume controls */
 	const char * const line_out_descrs[SCARLETT2_ANALOGUE_MAX];
@@ -391,6 +407,12 @@ struct scarlett2_device_info {
 	/* layout/order of the entries in the set_mux message */
 	struct scarlett2_mux_entry mux_assignment[SCARLETT2_MUX_TABLES]
 						 [SCARLETT2_MAX_MUX_ENTRIES];
+
+	/* map from meter level order returned by
+	 * SCARLETT2_USB_GET_METER to index into mux[] entries (same
+	 * as the order returned by scarlett2_meter_ctl_get())
+	 */
+	struct scarlett2_meter_entry meter_map[SCARLETT2_MAX_METER_ENTRIES];
 };
 
 struct scarlett2_data {
@@ -431,6 +453,7 @@ struct scarlett2_data {
 	u8 talkback_map[SCARLETT2_OUTPUT_MIX_MAX];
 	u8 msd_switch;
 	u8 standalone_switch;
+	u8 meter_level_map[SCARLETT2_MAX_METERS];
 	struct snd_kcontrol *sync_ctl;
 	struct snd_kcontrol *master_vol_ctl;
 	struct snd_kcontrol *vol_ctls[SCARLETT2_ANALOGUE_MAX];
@@ -493,6 +516,12 @@ static const struct scarlett2_device_info s6i6_gen2_info = {
 		{ SCARLETT2_PORT_TYPE_NONE,     0,  8 },
 		{ 0,                            0,  0 },
 	} },
+
+	.meter_map = {
+		{ 24,  6 },
+		{  0, 24 },
+		{  0,  0 },
+	}
 };
 
 static const struct scarlett2_device_info s18i8_gen2_info = {
@@ -540,6 +569,12 @@ static const struct scarlett2_device_info s18i8_gen2_info = {
 		{ SCARLETT2_PORT_TYPE_NONE,     0,  4 },
 		{ 0,                            0,  0 },
 	} },
+
+	.meter_map = {
+		{ 26, 18 },
+		{  0, 26 },
+		{  0,  0 },
+	}
 };
 
 static const struct scarlett2_device_info s18i20_gen2_info = {
@@ -592,6 +627,12 @@ static const struct scarlett2_device_info s18i20_gen2_info = {
 		{ SCARLETT2_PORT_TYPE_NONE,     0,  6 },
 		{ 0,                            0,  0 },
 	} },
+
+	.meter_map = {
+		{ 38, 18 },
+		{  0, 38 },
+		{  0,  0 },
+	}
 };
 
 static const struct scarlett2_device_info solo_gen3_info = {
@@ -657,6 +698,12 @@ static const struct scarlett2_device_info s4i4_gen3_info = {
 		{ SCARLETT2_PORT_TYPE_NONE,     0, 16 },
 		{ 0,                            0,  0 },
 	} },
+
+	.meter_map = {
+		{ 12,  6 },
+		{  0, 12 },
+		{  0,  0 },
+	}
 };
 
 static const struct scarlett2_device_info s8i6_gen3_info = {
@@ -708,6 +755,14 @@ static const struct scarlett2_device_info s8i6_gen3_info = {
 		{ SCARLETT2_PORT_TYPE_NONE,     0, 18 },
 		{ 0,                            0,  0 },
 	} },
+
+	.meter_map = {
+		{ 14, 8 },
+		{  0, 6 },
+		{ 22, 2 },
+		{  6, 8 },
+		{  0, 0 },
+	}
 };
 
 static const struct scarlett2_device_info s18i8_gen3_info = {
@@ -723,6 +778,7 @@ static const struct scarlett2_device_info s18i8_gen3_info = {
 
 	.line_out_remap_enable = 1,
 	.line_out_remap = { 0, 1, 6, 7, 2, 3, 4, 5 },
+	.line_out_unmap = { 0, 1, 4, 5, 6, 7, 2, 3 },
 
 	.line_out_descrs = {
 		"Monitor L",
@@ -776,6 +832,18 @@ static const struct scarlett2_device_info s18i8_gen3_info = {
 		{ SCARLETT2_PORT_TYPE_NONE,      0, 10 },
 		{ 0,                             0,  0 },
 	} },
+
+	.meter_map = {
+		{ 30, 10 },
+		{ 42,  8 },
+		{  0,  2 },
+		{  6,  2 },
+		{  2,  4 },
+		{  8,  2 },
+		{ 40,  2 },
+		{ 10, 20 },
+		{  0,  0 }
+	}
 };
 
 static const struct scarlett2_device_info s18i20_gen3_info = {
@@ -839,6 +907,15 @@ static const struct scarlett2_device_info s18i20_gen3_info = {
 		{ SCARLETT2_PORT_TYPE_NONE,      0, 24 },
 		{ 0,                             0,  0 },
 	} },
+
+	.meter_map = {
+		{ 45,  8 },
+		{ 55, 10 },
+		{  0, 20 },
+		{ 53,  2 },
+		{ 20, 25 },
+		{  0,  0 },
+	}
 };
 
 static const struct scarlett2_device_info clarett_2pre_info = {
@@ -881,6 +958,12 @@ static const struct scarlett2_device_info clarett_2pre_info = {
 		{ SCARLETT2_PORT_TYPE_NONE,     0, 26 },
 		{ 0,                            0,  0 },
 	} },
+
+	.meter_map = {
+		{ 22, 12 },
+		{  0, 22 },
+		{  0,  0 }
+	}
 };
 
 static const struct scarlett2_device_info clarett_4pre_info = {
@@ -928,6 +1011,12 @@ static const struct scarlett2_device_info clarett_4pre_info = {
 		{ SCARLETT2_PORT_TYPE_NONE,     0, 24 },
 		{ 0,                            0,  0 },
 	} },
+
+	.meter_map = {
+		{ 26, 18 },
+		{  0, 26 },
+		{  0,  0 }
+	}
 };
 
 static const struct scarlett2_device_info clarett_8pre_info = {
@@ -981,6 +1070,12 @@ static const struct scarlett2_device_info clarett_8pre_info = {
 		{ SCARLETT2_PORT_TYPE_NONE,     0, 22 },
 		{ 0,                            0,  0 },
 	} },
+
+	.meter_map = {
+		{ 38, 18 },
+		{  0, 38 },
+		{  0,  0 }
+	}
 };
 
 struct scarlett2_device_entry {
@@ -1688,6 +1783,79 @@ static void scarlett2_usb_populate_mux(struct scarlett2_data *private,
 	private->mux[dst_idx] = src_idx;
 }
 
+/* Update the meter level map
+ *
+ * The meter level data from the interface (SCARLETT2_USB_GET_METER
+ * request) is returned in mux_assignment order, but to avoid exposing
+ * that to userspace, scarlett2_meter_ctl_get() rearranges the data
+ * into scarlett2_ports order using the meter_level_map[] array which
+ * is set up by this function.
+ *
+ * In addition, the meter level data values returned from the
+ * interface are invalid for destinations where:
+ *
+ * - the source is "Off"; therefore we set those values to zero (map
+ *   value of 255)
+ *
+ * - the source is assigned to a previous (with respect to the
+ *   mux_assignment order) destination; therefore we set those values
+ *   to the value previously reported for that source
+ */
+static void scarlett2_update_meter_level_map(struct scarlett2_data *private)
+{
+	const struct scarlett2_device_info *info = private->info;
+	const int (*port_count)[SCARLETT2_PORT_DIRNS] = info->port_count;
+	int line_out_count =
+		port_count[SCARLETT2_PORT_TYPE_ANALOGUE][SCARLETT2_PORT_OUT];
+	const struct scarlett2_meter_entry *entry;
+
+	/* sources already assigned to a destination
+	 * value is 255 for None, otherwise the value of i
+	 * (index into array returned by
+	 * scarlett2_usb_get_meter_levels())
+	 */
+	u8 seen_src[SCARLETT2_MAX_SRCS] = { 1 };
+	u8 seen_src_value[SCARLETT2_MAX_SRCS] = { 255 };
+
+	/* index in meter_map[] order */
+	int i = 0;
+
+	/* go through the meter_map[] entries */
+	for (entry = info->meter_map;
+	     entry->count;
+	     entry++) {
+
+		/* fill in each meter_level_map[] entry */
+		int j, mux_idx;
+
+		for (j = 0, mux_idx = entry->start;
+		     j < entry->count;
+		     i++, j++, mux_idx++) {
+
+			/* convert mux_idx using line_out_unmap[] */
+			int map_mux_idx = (
+			    info->line_out_remap_enable &&
+			    mux_idx < line_out_count
+			) ? info->line_out_unmap[mux_idx]
+			  : mux_idx;
+
+			/* check which source is connected, and if
+			 * that source is already connected elsewhere,
+			 * use that existing connection's destination
+			 * for this meter entry instead
+			 */
+			int mux_src = private->mux[mux_idx];
+
+			if (!seen_src[mux_src]) {
+				seen_src[mux_src] = 1;
+				seen_src_value[mux_src] = i;
+			}
+			private->meter_level_map[map_mux_idx] =
+				seen_src_value[mux_src];
+		}
+	}
+}
+
 /* Send USB message to get mux inputs and then populate private->mux[] */
 static int scarlett2_usb_get_mux(struct usb_mixer_interface *mixer)
 {
@@ -1716,6 +1884,8 @@ static int scarlett2_usb_get_mux(struct usb_mixer_interface *mixer)
 	for (i = 0; i < count; i++)
 		scarlett2_usb_populate_mux(private, le32_to_cpu(data[i]));
 
+	scarlett2_update_meter_level_map(private);
+
 	return 0;
 }
 
@@ -1782,6 +1952,8 @@ static int scarlett2_usb_set_mux(struct usb_mixer_interface *mixer)
 			return err;
 	}
 
+	scarlett2_update_meter_level_map(private);
+
 	return 0;
 }
 
@@ -3619,6 +3791,8 @@ 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;
+	struct scarlett2_data *private = elem->head.mixer->private_data;
+	u8 *meter_level_map = private->meter_level_map;
 	u16 meter_levels[SCARLETT2_MAX_METERS];
 	int i, err;
 
@@ -3627,8 +3801,18 @@ static int scarlett2_meter_ctl_get(struct snd_kcontrol *kctl,
 	if (err < 0)
 		return err;
 
-	for (i = 0; i < elem->channels; i++)
-		ucontrol->value.integer.value[i] = meter_levels[i];
+	/* copy & translate from meter_levels[] using meter_level_map[] */
+	for (i = 0; i < elem->channels; i++) {
+		int idx = meter_level_map[i];
+		int value;
+
+		if (idx == 255)
+			value = 0;
+		else
+			value = meter_levels[idx];
+
+		ucontrol->value.integer.value[i] = value;
+	}
 
 	return 0;
 }