[ALSA] oxygen: add control filter to model struct

Allow the models to modify mixer controls before they are added to the
card.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

sound/pci/oxygen/oxygen.c

@@ -29,6 +29,7 @@
  */
 
 #include <linux/pci.h>
+#include <sound/control.h>
 #include <sound/core.h>
 #include <sound/initval.h>
 #include <sound/pcm.h>
@@ -244,18 +245,27 @@ static void set_ak5385_params(struct oxygen *chip,
 
 static const DECLARE_TLV_DB_LINEAR(ak4396_db_scale, TLV_DB_GAIN_MUTE, 0);
 
+static int ak4396_control_filter(struct snd_kcontrol_new *template)
+{
+	if (!strcmp(template->name, "Master Playback Volume")) {
+		template->access |= SNDRV_CTL_ELEM_ACCESS_TLV_READ;
+		template->tlv.p = ak4396_db_scale;
+	}
+	return 0;
+}
+
 static const struct oxygen_model model_generic = {
 	.shortname = "C-Media CMI8788",
 	.longname = "C-Media Oxygen HD Audio",
 	.chip = "CMI8788",
 	.owner = THIS_MODULE,
 	.init = generic_init,
+	.control_filter = ak4396_control_filter,
 	.cleanup = generic_cleanup,
 	.set_dac_params = set_ak4396_params,
 	.set_adc_params = set_wm8785_params,
 	.update_dac_volume = update_ak4396_volume,
 	.update_dac_mute = update_ak4396_mute,
-	.dac_tlv = ak4396_db_scale,
 	.used_channels = OXYGEN_CHANNEL_A |
 			 OXYGEN_CHANNEL_C |
 			 OXYGEN_CHANNEL_SPDIF |
@@ -269,12 +279,12 @@ static const struct oxygen_model model_meridian = {
 	.chip = "CMI8788",
 	.owner = THIS_MODULE,
 	.init = meridian_init,
+	.control_filter = ak4396_control_filter,
 	.cleanup = generic_cleanup,
 	.set_dac_params = set_ak4396_params,
 	.set_adc_params = set_ak5385_params,
 	.update_dac_volume = update_ak4396_volume,
 	.update_dac_mute = update_ak4396_mute,
-	.dac_tlv = ak4396_db_scale,
 	.used_channels = OXYGEN_CHANNEL_B |
 			 OXYGEN_CHANNEL_C |
 			 OXYGEN_CHANNEL_SPDIF |