ALSA: usb-audio: Add helper function for volume range checks

When a potentially insane volume range is found, the volume control
parameters will be printed in WARN level instead of DEBUG level.
Currently, it's done by emitting a open-coded usb_audio_warn() in the
corresponding check.

The following changes are about to add more checks against volumen
ranges. As the first step, extract the current check logic into a helper
function to improve readability.

No functional change intended.

Signed-off-by: Rong Zhang <i@rong.moe>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Link: https://patch.msgid.link/20260303194805.266158-3-i@rong.moe

1 files changed, 27 insertions, 16 deletions

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index df0d3df9c7ec..f52ca0d7e665 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1660,6 +1660,27 @@ static const struct usb_feature_control_info *get_feature_control_info(int contr
 	return NULL;
 }
 
+static bool check_insane_volume_range(struct usb_mixer_interface *mixer,
+				      struct snd_kcontrol *kctl,
+				      struct usb_mixer_elem_info *cval)
+{
+	int range = (cval->max - cval->min) / cval->res;
+
+	/*
+	 * Are there devices with volume range more than 255? I use a bit more
+	 * to be sure. 384 is a resolution magic number found on Logitech
+	 * devices. It will definitively catch all buggy Logitech devices.
+	 */
+	if (range > 384) {
+		usb_audio_warn(mixer->chip,
+			       "Warning! Unlikely big volume range (=%u), cval->res is probably wrong.",
+			       range);
+		return true;
+	}
+
+	return false;
+}
+
 static void __build_feature_ctl(struct usb_mixer_interface *mixer,
 				const struct usbmix_name_map *imap,
 				unsigned int ctl_mask, int control,
@@ -1673,7 +1694,6 @@ static void __build_feature_ctl(struct usb_mixer_interface *mixer,
 	struct snd_kcontrol *kctl;
 	struct usb_mixer_elem_info *cval;
 	const struct usbmix_name_map *map;
-	unsigned int range;
 
 	if (control == UAC_FU_GRAPHIC_EQUALIZER) {
 		/* FIXME: not supported yet */
@@ -1811,25 +1831,16 @@ static void __build_feature_ctl(struct usb_mixer_interface *mixer,
 
 	snd_usb_mixer_fu_apply_quirk(mixer, cval, unitid, kctl);
 
-	range = (cval->max - cval->min) / cval->res;
-	/*
-	 * Are there devices with volume range more than 255? I use a bit more
-	 * to be sure. 384 is a resolution magic number found on Logitech
-	 * devices. It will definitively catch all buggy Logitech devices.
-	 */
-	if (range > 384) {
-		usb_audio_warn(mixer->chip,
-			       "Warning! Unlikely big volume range (=%u), cval->res is probably wrong.",
-			       range);
-		usb_audio_warn(mixer->chip,
-			       "[%d] FU [%s] ch = %d, val = %d/%d/%d",
+	if (check_insane_volume_range(mixer, kctl, cval)) {
+		usb_audio_warn(mixer->chip, "[%d] FU [%s] ch = %d, val = %d/%d/%d\n",
 			       cval->head.id, kctl->id.name, cval->channels,
 			       cval->min, cval->max, cval->res);
+	} else {
+		usb_audio_dbg(mixer->chip, "[%d] FU [%s] ch = %d, val = %d/%d/%d\n",
+			      cval->head.id, kctl->id.name, cval->channels,
+			      cval->min, cval->max, cval->res);
 	}
 
-	usb_audio_dbg(mixer->chip, "[%d] FU [%s] ch = %d, val = %d/%d/%d\n",
-		      cval->head.id, kctl->id.name, cval->channels,
-		      cval->min, cval->max, cval->res);
 	snd_usb_mixer_add_control(&cval->head, kctl);
 }