[media] dtt200u-fe: handle errors on USB control messages

If something goes wrong, return an error code, instead of
assuming that everything went fine.
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>

drivers/media/usb/dvb-usb/dtt200u-fe.c

@@ -27,11 +27,17 @@ static int dtt200u_fe_read_status(struct dvb_frontend *fe,
 				  enum fe_status *stat)
 {
 	struct dtt200u_fe_state *state = fe->demodulator_priv;
+	int ret;
 
 	mutex_lock(&state->data_mutex);
 	state->data[0] = GET_TUNE_STATUS;
 
-	dvb_usb_generic_rw(state->d, state->data, 1, state->data, 3, 0);
+	ret = dvb_usb_generic_rw(state->d, state->data, 1, state->data, 3, 0);
+	if (ret < 0) {
+		*stat = 0;
+		mutex_unlock(&state->data_mutex);
+		return ret;
+	}
 
 	switch (state->data[0]) {
 		case 0x01:
@@ -53,25 +59,30 @@ static int dtt200u_fe_read_status(struct dvb_frontend *fe,
 static int dtt200u_fe_read_ber(struct dvb_frontend* fe, u32 *ber)
 {
 	struct dtt200u_fe_state *state = fe->demodulator_priv;
+	int ret;
 
 	mutex_lock(&state->data_mutex);
 	state->data[0] = GET_VIT_ERR_CNT;
 
-	dvb_usb_generic_rw(state->d, state->data, 1, state->data, 3, 0);
-	*ber = (state->data[0] << 16) | (state->data[1] << 8) | state->data[2];
+	ret = dvb_usb_generic_rw(state->d, state->data, 1, state->data, 3, 0);
+	if (ret >= 0)
+		*ber = (state->data[0] << 16) | (state->data[1] << 8) | state->data[2];
 
 	mutex_unlock(&state->data_mutex);
-	return 0;
+	return ret;
 }
 
 static int dtt200u_fe_read_unc_blocks(struct dvb_frontend* fe, u32 *unc)
 {
 	struct dtt200u_fe_state *state = fe->demodulator_priv;
+	int ret;
 
 	mutex_lock(&state->data_mutex);
 	state->data[0] = GET_RS_UNCOR_BLK_CNT;
 
-	dvb_usb_generic_rw(state->d, state->data, 1, state->data, 2, 0);
+	ret = dvb_usb_generic_rw(state->d, state->data, 1, state->data, 2, 0);
+	if (ret >= 0)
+		*unc = (state->data[0] << 8) | state->data[1];
 
 	mutex_unlock(&state->data_mutex);
 	return ret;
@@ -80,11 +91,14 @@ static int dtt200u_fe_read_unc_blocks(struct dvb_frontend* fe, u32 *unc)
 static int dtt200u_fe_read_signal_strength(struct dvb_frontend* fe, u16 *strength)
 {
 	struct dtt200u_fe_state *state = fe->demodulator_priv;
+	int ret;
 
 	mutex_lock(&state->data_mutex);
 	state->data[0] = GET_AGC;
 
-	dvb_usb_generic_rw(state->d, state->data, 1, state->data, 1, 0);
+	ret = dvb_usb_generic_rw(state->d, state->data, 1, state->data, 1, 0);
+	if (ret >= 0)
+		*strength = (state->data[0] << 8) | state->data[0];
 
 	mutex_unlock(&state->data_mutex);
 	return ret;
@@ -93,11 +107,14 @@ static int dtt200u_fe_read_signal_strength(struct dvb_frontend* fe, u16 *strengt
 static int dtt200u_fe_read_snr(struct dvb_frontend* fe, u16 *snr)
 {
 	struct dtt200u_fe_state *state = fe->demodulator_priv;
+	int ret;
 
 	mutex_lock(&state->data_mutex);
 	state->data[0] = GET_SNR;
 
-	dvb_usb_generic_rw(state->d, state->data, 1, state->data, 1, 0);
+	ret = dvb_usb_generic_rw(state->d, state->data, 1, state->data, 1, 0);
+	if (ret >= 0)
+		*snr = ~((state->data[0] << 8) | state->data[0]);
 
 	mutex_unlock(&state->data_mutex);
 	return ret;
@@ -134,6 +151,7 @@ static int dtt200u_fe_set_frontend(struct dvb_frontend *fe)
 {
 	struct dtv_frontend_properties *fep = &fe->dtv_property_cache;
 	struct dtt200u_fe_state *state = fe->demodulator_priv;
+	int ret;
 	u16 freq = fep->frequency / 250000;
 
 	mutex_lock(&state->data_mutex);
@@ -153,12 +171,16 @@ static int dtt200u_fe_set_frontend(struct dvb_frontend *fe)
 		goto ret;
 	}
 
-	dvb_usb_generic_write(state->d, state->data, 2);
+	ret = dvb_usb_generic_write(state->d, state->data, 2);
+	if (ret < 0)
+		goto ret;
 
 	state->data[0] = SET_RF_FREQ;
 	state->data[1] = freq & 0xff;
 	state->data[2] = (freq >> 8) & 0xff;
-	dvb_usb_generic_write(state->d, state->data, 3);
+	ret = dvb_usb_generic_write(state->d, state->data, 3);
+	if (ret < 0)
+		goto ret;
 
 ret:
 	mutex_unlock(&state->data_mutex);