ALSA: usb-audio: Add error checks against get_min_max*()

All callers of get_min_max*() ignore the latter's return code
completely. This means to ignore temporary errors at the probe time.
However, it is not optimal and leads to some maintenance burdens.

Return -EAGAIN for temporary errors, and check against it in the callers
of get_min_max*(). If any other error occurs, bail out of the caller
early.

Suggested-by: Takashi Iwai <tiwai@suse.de>
Link: https://lore.kernel.org/r/87ldewi4j8.wl-tiwai@suse.de
Signed-off-by: Rong Zhang <i@rong.moe>
Link: https://patch.msgid.link/20260411-uac-sticky-mixer-v1-1-29d62717befd@rong.moe
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index a25e8145af67e5e9ce80f6bb8b8672507212cae6..e5993364c8250ace4fa29eb0d4217c701186f262 100644 (file)
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -1264,7 +1264,7 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval,
                                      "%d:%d: cannot get min/max values for control %d (id %d)\n",
                                   cval->head.id, mixer_ctrl_intf(cval->head.mixer),
                                                               cval->control, cval->head.id);
-                       return -EINVAL;
+                       return -EAGAIN;
                }
                if (get_ctl_value(cval, UAC_GET_RES,
                                  (cval->control << 8) | minchn,
@@ -1388,6 +1388,7 @@ static int mixer_ctl_feature_info(struct snd_kcontrol *kcontrol,
                                  struct snd_ctl_elem_info *uinfo)
 {
        struct usb_mixer_elem_info *cval = snd_kcontrol_chip(kcontrol);
+       int ret;
 
        if (cval->val_type == USB_MIXER_BOOLEAN ||
            cval->val_type == USB_MIXER_INV_BOOLEAN)
@@ -1398,8 +1399,9 @@ static int mixer_ctl_feature_info(struct snd_kcontrol *kcontrol,
        if (cval->val_type != USB_MIXER_BOOLEAN &&
            cval->val_type != USB_MIXER_INV_BOOLEAN) {
                if (!cval->initialized) {
-                       get_min_max_with_quirks(cval, 0, kcontrol);
-                       if (cval->initialized && cval->dBmin >= cval->dBmax) {
+                       ret = get_min_max_with_quirks(cval, 0, kcontrol);
+                       if ((ret >= 0 || ret == -EAGAIN) &&
+                           cval->initialized && cval->dBmin >= cval->dBmax) {
                                kcontrol->vd[0].access &= 
                                        ~(SNDRV_CTL_ELEM_ACCESS_TLV_READ |
                                          SNDRV_CTL_ELEM_ACCESS_TLV_CALLBACK);
@@ -1743,6 +1745,7 @@ 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;
+       int ret;
 
        if (control == UAC_FU_GRAPHIC_EQUALIZER) {
                /* FIXME: not supported yet */
@@ -1856,10 +1859,10 @@ static void __build_feature_ctl(struct usb_mixer_interface *mixer,
        }
 
        /* get min/max values */
-       get_min_max_with_quirks(cval, 0, kctl);
+       ret = get_min_max_with_quirks(cval, 0, kctl);
 
        /* skip a bogus volume range */
-       if (cval->max <= cval->min) {
+       if ((ret < 0 && ret != -EAGAIN) || cval->max <= cval->min) {
                usb_audio_dbg(mixer->chip,
                              "[%d] FU [%s] skipped due to invalid volume\n",
                              cval->head.id, kctl->id.name);
@@ -2233,6 +2236,7 @@ static void build_mixer_unit_ctl(struct mixer_build *state,
        unsigned int i, len;
        struct snd_kcontrol *kctl;
        const struct usbmix_name_map *map;
+       int ret;
 
        map = find_map(state->map, unitid, 0);
        if (check_ignored_ctl(map))
@@ -2255,7 +2259,11 @@ static void build_mixer_unit_ctl(struct mixer_build *state,
        }
 
        /* get min/max values */
-       get_min_max(cval, 0);
+       ret = get_min_max(cval, 0);
+       if (ret < 0 && ret != -EAGAIN) {
+               usb_mixer_elem_info_free(cval);
+               return;
+       }
 
        kctl = snd_ctl_new1(&usb_feature_unit_ctl, cval);
        if (!kctl) {
@@ -2627,7 +2635,7 @@ static int build_audio_procunit(struct mixer_build *state, int unitid,
                                break;
                        }
 
-                       get_min_max(cval, valinfo->min_value);
+                       err = get_min_max(cval, valinfo->min_value);
                        break;
                }
                case USB_XU_CLOCK_RATE:
@@ -2639,11 +2647,16 @@ static int build_audio_procunit(struct mixer_build *state, int unitid,
                        cval->max = 5;
                        cval->res = 1;
                        cval->initialized = 1;
+                       err = 0;
                        break;
                default:
-                       get_min_max(cval, valinfo->min_value);
+                       err = get_min_max(cval, valinfo->min_value);
                        break;
                }
+               if (err < 0 && err != -EAGAIN) {
+                       usb_mixer_elem_info_free(cval);
+                       return err;
+               }
 
                err = get_cur_ctl_value(cval, cval->control << 8, &val);
                if (err < 0) {