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

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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
This commit is contained in:
Rong Zhang 2026-03-04 03:47:57 +08:00 committed by Takashi Iwai
parent 41d78cb724
commit 1060dbbbb2
1 changed files with 27 additions and 16 deletions
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43
sound/usb/mixer.c
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@ -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);
}