github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-11-07 06:17:02 +01:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

ALSA: usb-audio: Use fixed control index for us16x08 mixer elements

Browse Source 
The callbacks for us16x08 mixer elements assume that id.index points
to the channel to be operated, and the assumption is correct for now.
However, since the kctls are added via snd_usb_mixer_add_control() and
it looks for the empty slot if the same control name is already
present, in theory, the index can become more than the channel numbers
(if a conflicting name really happens).

Since the mixer code in us16x08 doesn't need the search for an empty
slot but requires the fixed index, this patch changes slightly how to
assign the kcontrols.  Now, a new argument is added to
snd_usb_mixer_add_list() in order to disable the empty slot search,
and use it in us16x08's add_new_ctl() helper function, instead.

Fixes: d2bb390a20 ("ALSA: usb-audio: Tascam US-16x08 DSP mixer quirk")
Reported-by: Sashiko <sashiko-bot@kernel.org>
Link: https://patch.msgid.link/20261014061406.162938-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2026-10-14 08:14:05 +02:00
parent ab669ac2bc
commit a68a688ce2
4 changed files with 15 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
sound/usb/mixer.c
View File

@ -649,20 +649,25 @@ static int check_matrix_bitmap(unsigned char *bmap,
/*
* add an alsa control element
* search and increment the index until an empty slot is found.
* when @look_for_empty is set, search and increment the index until an empty
* slot is found.
*
* if failed, give up and free the control instance.
*/
int snd_usb_mixer_add_list(struct usb_mixer_elem_list *list,
struct snd_kcontrol *kctl,
bool is_std_info)
bool is_std_info,
bool look_for_empty)
{
struct usb_mixer_interface *mixer = list->mixer;
int err;
while (snd_ctl_find_id(mixer->chip->card, &kctl->id))
kctl->id.index++;
if (look_for_empty) {
while (snd_ctl_find_id(mixer->chip->card, &kctl->id))
kctl->id.index++;
}
err = snd_ctl_add(mixer->chip->card, kctl);
if (err < 0) {
usb_audio_dbg(mixer->chip, "cannot add control (err = %d)\n",

5
sound/usb/mixer.h
View File

@ -113,10 +113,11 @@ int snd_usb_mixer_set_ctl_value(struct usb_mixer_elem_info *cval,
int snd_usb_mixer_add_list(struct usb_mixer_elem_list *list,
struct snd_kcontrol *kctl,
bool is_std_info);
bool is_std_info,
bool look_for_empty);
#define snd_usb_mixer_add_control(list, kctl) \
snd_usb_mixer_add_list(list, kctl, true)
snd_usb_mixer_add_list(list, kctl, true, true)
void snd_usb_mixer_elem_init_std(struct usb_mixer_elem_list *list,
struct usb_mixer_interface *mixer,

2
sound/usb/mixer_quirks.c
View File

@ -167,7 +167,7 @@ static int add_single_ctl_with_resume(struct usb_mixer_interface *mixer,
}
kctl->private_free = snd_usb_mixer_elem_free;
/* don't use snd_usb_mixer_add_control() here, this is a special list element */
return snd_usb_mixer_add_list(list, kctl, false);
return snd_usb_mixer_add_list(list, kctl, false, true);
}
/*

3
sound/usb/mixer_us16x08.c
View File

@ -1134,7 +1134,8 @@ static int add_new_ctl(struct usb_mixer_interface *mixer,
strscpy(kctl->id.name, name, sizeof(kctl->id.name));
err = snd_usb_mixer_add_control(&elem->head, kctl);
/* look_for_empty=false, as we want the fixed id.index as channel */
err = snd_usb_mixer_add_list(&elem->head, kctl, true, false);
if (err < 0)
return err;