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/[e-mail]
Signed-off-by: Takashi Iwai <[e-mail]>

sound/usb/6fire/control.c

···
 	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",
···
 	{}
 };
 
-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",
···
 	{}
 };
 
-static struct snd_kcontrol_new elements[] = {
+static const struct snd_kcontrol_new elements[] = {
 	{
 		.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 		.name = "Line/Phono Capture Route",
···
 	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

···
 	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,
···
  * 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,
···
  * 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

···
 
 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

···
 					    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,
···
 					  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,
···
 	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,
···
 	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),
···
 	},
 };
 
-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),
···
 	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),
···
 	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,
···
 				 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

···
 	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,
···
 	.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,
···
 	.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,
···
 	.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,
···
 	.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,
···
 	.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,
···
 	.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,
···
 	.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,
···
 	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,
···
 	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,
···
 	.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,
···
 	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,
···
 	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,
···
 	.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,
···
 	.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,
···
 	.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,
···
 	.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,
···
 	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,
···
 	.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

···
 };
 
 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;