From: Takashi Iwai <tiwai@suse.de>
Date: Fri, 27 Mar 2026 15:30:54 +0000 (+0100)
Subject: ALSA: usb-audio: Extend max number of channels to 64
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=16ee07bfa935f4f36deba896956f57d388221944;p=thirdparty%2Flinux.git

ALSA: usb-audio: Extend max number of channels to 64

The current limitation of 16 as MAX_CHANNELS is rather historical at
the time of UAC1 definition.  As there seem already devices with a
higher number of mixer channels, we should extend it too.  As an ad
hoc update, let's raise it to 64 so that it can still fit in a single
long-long integer.

Link: https://lore.kernel.org/F1B104A5-CD6A-4A26-AB46-14BF233C0579@getmailspring.com
Tested-by: Phil Willoughby <willerz@gmail.com>
Link: https://patch.msgid.link/20260327153056.691575-2-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
---

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index e764757979e00..69026cf54979a 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1725,7 +1725,7 @@ static bool check_insane_volume_range(struct usb_mixer_interface *mixer,
 
 static void __build_feature_ctl(struct usb_mixer_interface *mixer,
 				const struct usbmix_name_map *imap,
-				unsigned int ctl_mask, int control,
+				u64 ctl_mask, int control,
 				struct usb_audio_term *iterm,
 				struct usb_audio_term *oterm,
 				int unitid, int nameid, int readonly_mask)
@@ -1887,7 +1887,7 @@ static void __build_feature_ctl(struct usb_mixer_interface *mixer,
 }
 
 static void build_feature_ctl(struct mixer_build *state, void *raw_desc,
-			      unsigned int ctl_mask, int control,
+			      u64 ctl_mask, int control,
 			      struct usb_audio_term *iterm, int unitid,
 			      int readonly_mask)
 {
@@ -1899,7 +1899,7 @@ static void build_feature_ctl(struct mixer_build *state, void *raw_desc,
 }
 
 static void build_feature_ctl_badd(struct usb_mixer_interface *mixer,
-			      unsigned int ctl_mask, int control, int unitid,
+			      u64 ctl_mask, int control, int unitid,
 			      const struct usbmix_name_map *badd_map)
 {
 	__build_feature_ctl(mixer, badd_map, ctl_mask, control,
@@ -2075,7 +2075,7 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid,
 		bmaControls = ftr->bmaControls;
 	}
 
-	if (channels > 32) {
+	if (channels > MAX_CHANNELS) {
 		usb_audio_info(state->chip,
 			       "usbmixer: too many channels (%d) in unit %d\n",
 			       channels, unitid);
@@ -2113,7 +2113,7 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid,
 	if (state->mixer->protocol == UAC_VERSION_1) {
 		/* check all control types */
 		for (i = 0; i < 10; i++) {
-			unsigned int ch_bits = 0;
+			u64 ch_bits = 0;
 			int control = audio_feature_info[i].control;
 
 			for (j = 0; j < channels; j++) {
@@ -2139,7 +2139,7 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid,
 		}
 	} else { /* UAC_VERSION_2/3 */
 		for (i = 0; i < ARRAY_SIZE(audio_feature_info); i++) {
-			unsigned int ch_bits = 0;
+			u64 ch_bits = 0;
 			unsigned int ch_read_only = 0;
 			int control = audio_feature_info[i].control;
 
@@ -3452,7 +3452,7 @@ static void snd_usb_mixer_dump_cval(struct snd_info_buffer *buffer,
 		[USB_MIXER_U32] = "U32",
 		[USB_MIXER_BESPOKEN] = "BESPOKEN",
 	};
-	snd_iprintf(buffer, "    Info: id=%i, control=%i, cmask=0x%x, "
+	snd_iprintf(buffer, "    Info: id=%i, control=%i, cmask=0x%llx, "
 			    "channels=%i, type=\"%s\"\n", cval->head.id,
 			    cval->control, cval->cmask, cval->channels,
 			    val_types[cval->val_type]);
diff --git a/sound/usb/mixer.h b/sound/usb/mixer.h
index 167fbfcf01ace..afbb3dd9f177b 100644
--- a/sound/usb/mixer.h
+++ b/sound/usb/mixer.h
@@ -44,7 +44,7 @@ struct usb_mixer_interface {
 	void (*private_suspend)(struct usb_mixer_interface *mixer);
 };
 
-#define MAX_CHANNELS	16	/* max logical channels */
+#define MAX_CHANNELS	64	/* max logical channels */
 
 enum {
 	USB_MIXER_BOOLEAN,
@@ -81,7 +81,7 @@ struct usb_mixer_elem_list {
 struct usb_mixer_elem_info {
 	struct usb_mixer_elem_list head;
 	unsigned int control;	/* CS or ICN (high byte) */
-	unsigned int cmask; /* channel mask bitmap: 0 = master */
+	u64 cmask; /* channel mask bitmap: 0 = master */
 	unsigned int idx_off; /* Control index offset */
 	unsigned int ch_readonly;
 	unsigned int master_readonly;