[alsa-devel] [PATCH] sound/usb: add dB range mapping quirks.
Yao-Wen Mao
yaowen at google.com
Tue Jul 28 10:06:45 CEST 2015
Some usb audio devices don't follow the specification of the
volume range. Add dB_mapping_quirks to fix some devices' dB
ranges so that the function snd_mixer_selem_set_playback_dB in
alsa-lib can set the correct value for those devices.
Signed-off-by: Yao-Wen Mao <yaowen at google.com>
---
sound/usb/mixer.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 6b3acba..b6b27dc 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -933,6 +933,32 @@ static void volume_control_quirks(struct usb_mixer_elem_info *cval,
}
}
+/* dB mapping quirks */
+static void dB_mapping_quirks(struct usb_mixer_elem_info *cval,
+ struct snd_kcontrol *kctl)
+{
+ switch (cval->mixer->chip->usb_id) {
+ case USB_ID(0x05a7, 0x1020): /* Bose Companion 5 */
+ if (strcmp(kctl->id.name, "PCM Playback Volume") == 0) {
+ cval->dBmin = (convert_signed_value(cval, cval->min) * 100) / 16;
+ cval->dBmax = (convert_signed_value(cval, cval->max) * 100) / 16;
+ }
+ break;
+ case USB_ID(0x21b4, 0x0081): /* Dragonfly DAC 1.2 */
+ if (strcmp(kctl->id.name, "PCM Playback Volume") == 0) {
+ cval->dBmin = convert_signed_value(cval, cval->min) * 100;
+ cval->dBmax = convert_signed_value(cval, cval->max) * 100;
+ }
+ break;
+ case USB_ID(0x046d, 0x0a29): /* Logitech H800 */
+ if (strcmp(kctl->id.name, "PCM Playback Volume") == 0) {
+ cval->dBmin = convert_signed_value(cval, cval->min);
+ cval->dBmax = convert_signed_value(cval, cval->max);
+ }
+ break;
+ }
+}
+
/*
* retrieve the minimum and maximum values for the specified control
*/
@@ -1027,6 +1053,10 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
*/
cval->dBmin = (convert_signed_value(cval, cval->min) * 100) / 256;
cval->dBmax = (convert_signed_value(cval, cval->max) * 100) / 256;
+
+ if (kctl)
+ dB_mapping_quirks(cval, kctl);
+
if (cval->dBmin > cval->dBmax) {
/* something is wrong; assume it's either from/to 0dB */
if (cval->dBmin < 0)
--
2.5.0.rc2.392.g76e840b
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