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

["Cássio Gabriel" <cassiogabrielcontato@gmail.com>]

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