[PATCH 4/4] ALSA: usb-audio: Update US-16x08 EQ/comp shadow state after successful writes

Cássio Gabriel
2026-04-19T20:31:39Z

snd_us16x08_comp_put() and snd_us16x08_eq_put() update their
software stores before sending the USB write. If the transfer
fails, later get callbacks report a value the hardware never
accepted.

Build the outgoing message from the current store plus the
pending value, then commit the store only after a successful
write.

Fixes: d2bb390a2081 ("ALSA: usb-audio: Tascam US-16x08 DSP mixer quirk")
Cc: stable@vger.kernel.org
Signed-off-by: Cássio Gabriel <cassiogabrielcontato@gmail.com>
---
sound/usb/mixer_us16x08.c | 78 +++++++++++++++++++++++++++++++----------------
1 file changed, 52 insertions(+), 26 deletions(-)

diff --git a/sound/usb/mixer_us16x08.c b/sound/usb/mixer_us16x08.c
index fcf7dfa4aa84..ebff185cbd2c 100644
--- a/sound/usb/mixer_us16x08.c
+++ b/sound/usb/mixer_us16x08.c
@@ -435,6 +435,7 @@ static int snd_us16x08_comp_put(struct snd_kcontrol *kcontrol,
int index = ucontrol->id.index;
char buf[sizeof(comp_msg)];
int val_idx, val;
+ int threshold, ratio, attack, release, gain, switch_on;
int err;

val = ucontrol->value.integer.value[0];
@@ -447,36 +448,61 @@ static int snd_us16x08_comp_put(struct snd_kcontrol *kcontrol,
/* new control value incl. bias*/
val_idx = elem->head.id - SND_US16X08_ID_COMP_BASE;

- store->val[val_idx][index] = ucontrol->value.integer.value[0];
+ threshold = store->val[COMP_STORE_IDX(SND_US16X08_ID_COMP_THRESHOLD)]
+ [index];
+ ratio = store->val[COMP_STORE_IDX(SND_US16X08_ID_COMP_RATIO)][index];
+ attack = store->val[COMP_STORE_IDX(SND_US16X08_ID_COMP_ATTACK)][index];
+ release = store->val[COMP_STORE_IDX(SND_US16X08_ID_COMP_RELEASE)]
+ [index];
+ gain = store->val[COMP_STORE_IDX(SND_US16X08_ID_COMP_GAIN)][index];
+ switch_on = store->val[COMP_STORE_IDX(SND_US16X08_ID_COMP_SWITCH)]
+ [index];
+
+ switch (val_idx) {
+ case COMP_STORE_IDX(SND_US16X08_ID_COMP_THRESHOLD):
+ threshold = val;
+ break;
+ case COMP_STORE_IDX(SND_US16X08_ID_COMP_RATIO):
+ ratio = val;
+ break;
+ case COMP_STORE_IDX(SND_US16X08_ID_COMP_ATTACK):
+ attack = val;
+ break;
+ case COMP_STORE_IDX(SND_US16X08_ID_COMP_RELEASE):
+ release = val;
+ break;
+ case COMP_STORE_IDX(SND_US16X08_ID_COMP_GAIN):
+ gain = val;
+ break;
+ case COMP_STORE_IDX(SND_US16X08_ID_COMP_SWITCH):
+ switch_on = val;
+ break;
+ }

/* prepare compressor URB message from template */
memcpy(buf, comp_msg, sizeof(comp_msg));

/* place comp values in message buffer watch bias! */
- buf[8] = store->val[
- COMP_STORE_IDX(SND_US16X08_ID_COMP_THRESHOLD)][index]
- - SND_US16X08_COMP_THRESHOLD_BIAS;
- buf[11] = ratio_map[store->val[
- COMP_STORE_IDX(SND_US16X08_ID_COMP_RATIO)][index]];
- buf[14] = store->val[COMP_STORE_IDX(SND_US16X08_ID_COMP_ATTACK)][index]
- + SND_US16X08_COMP_ATTACK_BIAS;
- buf[17] = store->val[COMP_STORE_IDX(SND_US16X08_ID_COMP_RELEASE)][index]
- + SND_US16X08_COMP_RELEASE_BIAS;
- buf[20] = store->val[COMP_STORE_IDX(SND_US16X08_ID_COMP_GAIN)][index];
- buf[26] = store->val[COMP_STORE_IDX(SND_US16X08_ID_COMP_SWITCH)][index];
+ buf[8] = threshold - SND_US16X08_COMP_THRESHOLD_BIAS;
+ buf[11] = ratio_map[ratio];
+ buf[14] = attack + SND_US16X08_COMP_ATTACK_BIAS;
+ buf[17] = release + SND_US16X08_COMP_RELEASE_BIAS;
+ buf[20] = gain;
+ buf[26] = switch_on;

/* place channel selector in message buffer */
buf[5] = index + 1;

err = snd_us16x08_send_urb(chip, buf, sizeof(comp_msg));

- if (err > 0) {
- elem->cached |= 1 << index;
- elem->cache_val[index] = val;
- } else {
+ if (err < 0) {
usb_audio_dbg(chip, "Failed to set compressor, err:%d\n", err);
+ return err;
}

+ store->val[val_idx][index] = val;
+ elem->cached |= 1 << index;
+ elem->cache_val[index] = val;
return 1;
}

@@ -578,11 +604,10 @@ static int snd_us16x08_eq_put(struct snd_kcontrol *kcontrol,
/* copy URB buffer from EQ template */
memcpy(buf, eqs_msq, sizeof(eqs_msq));

- store->val[b_idx][p_idx][index] = val;
- buf[20] = store->val[b_idx][3][index];
- buf[17] = store->val[b_idx][2][index];
- buf[14] = store->val[b_idx][1][index];
- buf[11] = store->val[b_idx][0][index];
+ buf[20] = p_idx == 3 ? val : store->val[b_idx][3][index];
+ buf[17] = p_idx == 2 ? val : store->val[b_idx][2][index];
+ buf[14] = p_idx == 1 ? val : store->val[b_idx][1][index];
+ buf[11] = p_idx == 0 ? val : store->val[b_idx][0][index];

/* place channel index in URB buffer */
buf[5] = index + 1;
@@ -592,14 +617,15 @@ static int snd_us16x08_eq_put(struct snd_kcontrol *kcontrol,

err = snd_us16x08_send_urb(chip, buf, sizeof(eqs_msq));

- if (err > 0) {
- /* store new value in EQ band cache */
- elem->cached |= 1 << index;
- elem->cache_val[index] = val;
- } else {
+ if (err < 0) {
usb_audio_dbg(chip, "Failed to set eq param, err:%d\n", err);
+ return err;
}

+ store->val[b_idx][p_idx][index] = val;
+ /* store new value in EQ band cache */
+ elem->cached |= 1 << index;
+ elem->cache_val[index] = val;
return 1;
}

--
2.53.0