ALSA: usb-audio: add dB range mapping for some devices

Add the correct dB ranges of Bose Companion 5 and Drangonfly DAC 1.2.
Signed-off-by: Yao-Wen Mao <yaowen@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/mixer_maps.c

@@ -341,6 +341,20 @@ static const struct usbmix_name_map scms_usb3318_map[] = {
 	{ 0 }
 };
 
+/* Bose companion 5, the dB conversion factor is 16 instead of 256 */
+static struct usbmix_dB_map bose_companion5_dB = {-5006, -6};
+static struct usbmix_name_map bose_companion5_map[] = {
+	{ 3, NULL, .dB = &bose_companion5_dB },
+	{ 0 }	/* terminator */
+};
+
+/* Dragonfly DAC 1.2, the dB conversion factor is 1 instead of 256 */
+static struct usbmix_dB_map dragonfly_1_2_dB = {0, 5000};
+static struct usbmix_name_map dragonfly_1_2_map[] = {
+	{ 7, NULL, .dB = &dragonfly_1_2_dB },
+	{ 0 }	/* terminator */
+};
+
 /*
  * Control map entries
  */
@@ -451,6 +465,16 @@ static struct usbmix_ctl_map usbmix_ctl_maps[] = {
 		.id = USB_ID(0x25c4, 0x0003),
 		.map = scms_usb3318_map,
 	},
+	{
+		/* Bose Companion 5 */
+		.id = USB_ID(0x05a7, 0x1020),
+		.map = bose_companion5_map,
+	},
+	{
+		/* Dragonfly DAC 1.2 */
+		.id = USB_ID(0x21b4, 0x0081),
+		.map = dragonfly_1_2_map,
+	},
 	{ 0 } /* terminator */
 };