From fca9c850042a7ab4828ce3a9caa8bc40ea09856a Mon Sep 17 00:00:00 2001 From: Cássio Gabriel Date: Tue, 21 Apr 2026 21:53:52 -0300 Subject: ALSA: usb-audio: Avoid false E-MU sample-rate notifications MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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: 7d2b451e65d2 ("ALSA: usb-audio - Added functionality for E-mu 0404USB/0202USB/TrackerPre") Cc: stable@vger.kernel.org Signed-off-by: Cássio Gabriel Link: https://patch.msgid.link/20260421-alsa-emuusb-samplerate-notify-v1-1-8b63bbc1d7f1@gmail.com Signed-off-by: Takashi Iwai --- sound/usb/mixer_quirks.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c index a01510a855c2..5194a2ac1ea8 100644 --- a/sound/usb/mixer_quirks.c +++ b/sound/usb/mixer_quirks.c @@ -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; } } -- cgit v1.2.3