ALSA: usb: Constify snd_kcontrol_new items

Most of snd_kcontrol_new definitions are read-only and passed as-is.
Let's declare them as const for further optimization.

There should be no functional changes by this patch.

Link: https://lore.kernel.org/r/20200103081714.9560-42-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/6fire/control.c

@@ -397,7 +397,7 @@ static int usb6fire_control_digital_thru_get(struct snd_kcontrol *kcontrol,
 	return 0;
 }
 
-static struct snd_kcontrol_new vol_elements[] = {
+static const struct snd_kcontrol_new vol_elements[] = {
 	{
 		.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 		.name = "Analog Playback Volume",
@@ -437,7 +437,7 @@ static struct snd_kcontrol_new vol_elements[] = {
 	{}
 };
 
-static struct snd_kcontrol_new mute_elements[] = {
+static const struct snd_kcontrol_new mute_elements[] = {
 	{
 		.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 		.name = "Analog Playback Switch",
@@ -471,7 +471,7 @@ static struct snd_kcontrol_new mute_elements[] = {
 	{}
 };
 
-static struct snd_kcontrol_new elements[] = {
+static const struct snd_kcontrol_new elements[] = {
 	{
 		.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 		.name = "Line/Phono Capture Route",
@@ -517,7 +517,7 @@ static int usb6fire_control_add_virtual(
 	struct control_runtime *rt,
 	struct snd_card *card,
 	char *name,
-	struct snd_kcontrol_new *elems)
+	const struct snd_kcontrol_new *elems)
 {
 	int ret;
 	int i;

sound/usb/mixer.c

@@ -1445,7 +1445,7 @@ static int mixer_ctl_connector_get(struct snd_kcontrol *kcontrol,
 	return 0;
 }
 
-static struct snd_kcontrol_new usb_feature_unit_ctl = {
+static const struct snd_kcontrol_new usb_feature_unit_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.name = "", /* will be filled later manually */
 	.info = mixer_ctl_feature_info,
@@ -1466,7 +1466,7 @@ static const struct snd_kcontrol_new usb_feature_unit_ctl_ro = {
  * A control which shows the boolean value from reading a UAC control on
  * the master channel.
  */
-static struct snd_kcontrol_new usb_bool_master_control_ctl_ro = {
+static const struct snd_kcontrol_new usb_bool_master_control_ctl_ro = {
 	.iface = SNDRV_CTL_ELEM_IFACE_CARD,
 	.name = "", /* will be filled later manually */
 	.access = SNDRV_CTL_ELEM_ACCESS_READ,
@@ -1488,7 +1488,7 @@ static const struct snd_kcontrol_new usb_connector_ctl_ro = {
  * This symbol is exported in order to allow the mixer quirks to
  * hook up to the standard feature unit control mechanism
  */
-struct snd_kcontrol_new *snd_usb_feature_unit_ctl = &usb_feature_unit_ctl;
+const struct snd_kcontrol_new *snd_usb_feature_unit_ctl = &usb_feature_unit_ctl;
 
 /*
  * build a feature control

sound/usb/mixer.h

@@ -116,6 +116,6 @@ int snd_usb_get_cur_mix_value(struct usb_mixer_elem_info *cval,
 
 extern void snd_usb_mixer_elem_free(struct snd_kcontrol *kctl);
 
-extern struct snd_kcontrol_new *snd_usb_feature_unit_ctl;
+extern const struct snd_kcontrol_new *snd_usb_feature_unit_ctl;
 
 #endif /* __USBMIXER_H */

sound/usb/mixer_quirks.c

@@ -507,7 +507,7 @@ static int snd_emu0204_ch_switch_resume(struct usb_mixer_elem_list *list)
 					    list->kctl->private_value);
 }
 
-static struct snd_kcontrol_new snd_emu0204_control = {
+static const struct snd_kcontrol_new snd_emu0204_control = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.name = "Front Jack Channels",
 	.info = snd_emu0204_ch_switch_info,
@@ -575,7 +575,7 @@ static int snd_xonar_u1_switch_resume(struct usb_mixer_elem_list *list)
 					  list->kctl->private_value);
 }
 
-static struct snd_kcontrol_new snd_xonar_u1_output_switch = {
+static const struct snd_kcontrol_new snd_xonar_u1_output_switch = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.name = "Digital Playback Switch",
 	.info = snd_ctl_boolean_mono_info,
@@ -702,7 +702,7 @@ static int snd_mbox1_switch_resume(struct usb_mixer_elem_list *list)
 	return snd_mbox1_switch_update(list->mixer, list->kctl->private_value);
 }
 
-static struct snd_kcontrol_new snd_mbox1_switch = {
+static const struct snd_kcontrol_new snd_mbox1_switch = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.name = "Clock Source",
 	.index = 0,
@@ -787,7 +787,7 @@ static int snd_nativeinstruments_control_put(struct snd_kcontrol *kcontrol,
 	return err < 0 ? err : 1;
 }
 
-static struct snd_kcontrol_new snd_nativeinstruments_ta6_mixers[] = {
+static const struct snd_kcontrol_new snd_nativeinstruments_ta6_mixers[] = {
 	{
 		.name = "Direct Thru Channel A",
 		.private_value = _MAKE_NI_CONTROL(0x01, 0x03),
@@ -806,7 +806,7 @@ static struct snd_kcontrol_new snd_nativeinstruments_ta6_mixers[] = {
 	},
 };
 
-static struct snd_kcontrol_new snd_nativeinstruments_ta10_mixers[] = {
+static const struct snd_kcontrol_new snd_nativeinstruments_ta10_mixers[] = {
 	{
 		.name = "Direct Thru Channel A",
 		.private_value = _MAKE_NI_CONTROL(0x01, 0x03),
@@ -1662,7 +1662,7 @@ static int snd_microii_spdif_switch_put(struct snd_kcontrol *kcontrol,
 	return err < 0 ? err : 1;
 }
 
-static struct snd_kcontrol_new snd_microii_mixer_spdif[] = {
+static const struct snd_kcontrol_new snd_microii_mixer_spdif[] = {
 	{
 		.iface =    SNDRV_CTL_ELEM_IFACE_PCM,
 		.name =     SNDRV_CTL_NAME_IEC958("", PLAYBACK, DEFAULT),
@@ -1769,7 +1769,7 @@ static int snd_soundblaster_e1_switch_info(struct snd_kcontrol *kcontrol,
 	return snd_ctl_enum_info(uinfo, 1, ARRAY_SIZE(texts), texts);
 }
 
-static struct snd_kcontrol_new snd_soundblaster_e1_input_switch = {
+static const struct snd_kcontrol_new snd_soundblaster_e1_input_switch = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.name = "Input Source",
 	.info = snd_soundblaster_e1_switch_info,
@@ -2093,7 +2093,7 @@ static int snd_rme_sync_source_info(struct snd_kcontrol *kcontrol,
 				 ARRAY_SIZE(sync_sources), sync_sources);
 }
 
-static struct snd_kcontrol_new snd_rme_controls[] = {
+static const struct snd_kcontrol_new snd_rme_controls[] = {
 	{
 		.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 		.name = "AES Rate",

sound/usb/mixer_us16x08.c

@@ -760,7 +760,7 @@ static int snd_us16x08_meter_put(struct snd_kcontrol *kcontrol,
 	return 1;
 }
 
-static struct snd_kcontrol_new snd_us16x08_ch_boolean_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_ch_boolean_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -770,7 +770,7 @@ static struct snd_kcontrol_new snd_us16x08_ch_boolean_ctl = {
 	.private_value = SND_US16X08_KCSET(SND_US16X08_NO_BIAS, 1, 0, 1)
 };
 
-static struct snd_kcontrol_new snd_us16x08_ch_int_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_ch_int_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -780,7 +780,7 @@ static struct snd_kcontrol_new snd_us16x08_ch_int_ctl = {
 	.private_value = SND_US16X08_KCSET(SND_US16X08_FADER_BIAS, 1, 0, 133)
 };
 
-static struct snd_kcontrol_new snd_us16x08_pan_int_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_pan_int_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -790,7 +790,7 @@ static struct snd_kcontrol_new snd_us16x08_pan_int_ctl = {
 	.private_value = SND_US16X08_KCSET(SND_US16X08_FADER_BIAS, 1, 0, 255)
 };
 
-static struct snd_kcontrol_new snd_us16x08_master_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_master_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 1,
@@ -800,7 +800,7 @@ static struct snd_kcontrol_new snd_us16x08_master_ctl = {
 	.private_value = SND_US16X08_KCSET(SND_US16X08_FADER_BIAS, 1, 0, 133)
 };
 
-static struct snd_kcontrol_new snd_us16x08_route_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_route_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 8,
@@ -810,7 +810,7 @@ static struct snd_kcontrol_new snd_us16x08_route_ctl = {
 	.private_value = SND_US16X08_KCSET(SND_US16X08_NO_BIAS, 1, 0, 9)
 };
 
-static struct snd_kcontrol_new snd_us16x08_bus_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_bus_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 1,
@@ -820,7 +820,7 @@ static struct snd_kcontrol_new snd_us16x08_bus_ctl = {
 	.private_value = SND_US16X08_KCSET(SND_US16X08_NO_BIAS, 1, 0, 1)
 };
 
-static struct snd_kcontrol_new snd_us16x08_compswitch_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_compswitch_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -830,7 +830,7 @@ static struct snd_kcontrol_new snd_us16x08_compswitch_ctl = {
 	.private_value = SND_US16X08_KCSET(SND_US16X08_NO_BIAS, 1, 0, 1)
 };
 
-static struct snd_kcontrol_new snd_us16x08_comp_threshold_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_comp_threshold_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -841,7 +841,7 @@ static struct snd_kcontrol_new snd_us16x08_comp_threshold_ctl = {
 	0, 0x20)
 };
 
-static struct snd_kcontrol_new snd_us16x08_comp_ratio_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_comp_ratio_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -852,7 +852,7 @@ static struct snd_kcontrol_new snd_us16x08_comp_ratio_ctl = {
 	sizeof(ratio_map) - 1), /*max*/
 };
 
-static struct snd_kcontrol_new snd_us16x08_comp_gain_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_comp_gain_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -862,7 +862,7 @@ static struct snd_kcontrol_new snd_us16x08_comp_gain_ctl = {
 	.private_value = SND_US16X08_KCSET(SND_US16X08_NO_BIAS, 1, 0, 0x14)
 };
 
-static struct snd_kcontrol_new snd_us16x08_comp_attack_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_comp_attack_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -873,7 +873,7 @@ static struct snd_kcontrol_new snd_us16x08_comp_attack_ctl = {
 	SND_US16X08_KCSET(SND_US16X08_COMP_ATTACK_BIAS, 1, 0, 0xc6),
 };
 
-static struct snd_kcontrol_new snd_us16x08_comp_release_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_comp_release_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -884,7 +884,7 @@ static struct snd_kcontrol_new snd_us16x08_comp_release_ctl = {
 	SND_US16X08_KCSET(SND_US16X08_COMP_RELEASE_BIAS, 1, 0, 0x63),
 };
 
-static struct snd_kcontrol_new snd_us16x08_eq_gain_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_eq_gain_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -894,7 +894,7 @@ static struct snd_kcontrol_new snd_us16x08_eq_gain_ctl = {
 	.private_value = SND_US16X08_KCSET(SND_US16X08_NO_BIAS, 1, 0, 24),
 };
 
-static struct snd_kcontrol_new snd_us16x08_eq_low_freq_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_eq_low_freq_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -904,7 +904,7 @@ static struct snd_kcontrol_new snd_us16x08_eq_low_freq_ctl = {
 	.private_value = SND_US16X08_KCSET(SND_US16X08_NO_BIAS, 1, 0, 0x1F),
 };
 
-static struct snd_kcontrol_new snd_us16x08_eq_mid_freq_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_eq_mid_freq_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -914,7 +914,7 @@ static struct snd_kcontrol_new snd_us16x08_eq_mid_freq_ctl = {
 	.private_value = SND_US16X08_KCSET(SND_US16X08_NO_BIAS, 1, 0, 0x3F)
 };
 
-static struct snd_kcontrol_new snd_us16x08_eq_mid_width_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_eq_mid_width_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -924,7 +924,7 @@ static struct snd_kcontrol_new snd_us16x08_eq_mid_width_ctl = {
 	.private_value = SND_US16X08_KCSET(SND_US16X08_NO_BIAS, 1, 0, 0x06)
 };
 
-static struct snd_kcontrol_new snd_us16x08_eq_high_freq_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_eq_high_freq_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -935,7 +935,7 @@ static struct snd_kcontrol_new snd_us16x08_eq_high_freq_ctl = {
 	SND_US16X08_KCSET(SND_US16X08_EQ_HIGHFREQ_BIAS, 1, 0, 0x1F)
 };
 
-static struct snd_kcontrol_new snd_us16x08_eq_switch_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_eq_switch_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 16,
@@ -945,7 +945,7 @@ static struct snd_kcontrol_new snd_us16x08_eq_switch_ctl = {
 	.private_value = SND_US16X08_KCSET(SND_US16X08_NO_BIAS, 1, 0, 1)
 };
 
-static struct snd_kcontrol_new snd_us16x08_meter_ctl = {
+static const struct snd_kcontrol_new snd_us16x08_meter_ctl = {
 	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 	.access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
 	.count = 1,

sound/usb/mixer_us16x08.h

@@ -108,7 +108,7 @@ struct snd_us16x08_meter_store {
 };
 
 struct snd_us16x08_control_params {
-	struct snd_kcontrol_new *kcontrol_new;
+	const struct snd_kcontrol_new *kcontrol_new;
 	int control_id;
 	int type;
 	int num_channels;