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ALSA: usb-audio: Avoid false E-MU sample-rate notifications

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snd_emuusb_set_samplerate() unconditionally notifies the E-MU
SampleRate Extension Unit control after issuing SET_CUR.

If snd_usb_mixer_set_ctl_value() fails, the control value has not
changed, yet snd_usb_mixer_notify_id() still invalidates the cache and
emits a value-change event to userspace.

Notify the control only after a successful write.

Fixes: 7d2b451e65 ("ALSA: usb-audio - Added functionality for E-mu 0404USB/0202USB/TrackerPre")
Cc: stable@vger.kernel.org
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
Link: https://patch.msgid.link/20260421-alsa-emuusb-samplerate-notify-v1-1-8b63bbc1d7f1@gmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Cássio Gabriel 2026-04-21 21:53:52 -03:00 committed by Takashi Iwai
parent eacda758e3
commit fca9c85004
1 changed files with 6 additions and 4 deletions
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10
sound/usb/mixer_quirks.c
View File

@ -1538,15 +1538,17 @@ void snd_emuusb_set_samplerate(struct snd_usb_audio *chip,
{
struct usb_mixer_interface *mixer;
struct usb_mixer_elem_info *cval;
int err;
int unitid = 12; /* SampleRate ExtensionUnit ID */
list_for_each_entry(mixer, &chip->mixer_list, list) {
if (mixer->id_elems[unitid]) {
cval = mixer_elem_list_to_info(mixer->id_elems[unitid]);
snd_usb_mixer_set_ctl_value(cval, UAC_SET_CUR,
cval->control << 8,
samplerate_id);
snd_usb_mixer_notify_id(mixer, unitid);
err = snd_usb_mixer_set_ctl_value(cval, UAC_SET_CUR,
cval->control << 8,
samplerate_id);
if (!err)
snd_usb_mixer_notify_id(mixer, unitid);
break;
}
}