V4L/DVB (7348): tuner-simple: do not send i2c commands if there is no i2c adapter

if (priv->i2c_props.adap == NULL) then exit any function that would
send commands over the i2c bus.  We allow drivers to attach without an
i2c adapter for cases where the dvb demod accesses the tuner directly
via calc_regs.

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/tuner-simple.c

@@ -149,7 +149,12 @@ static inline int tuner_afcstatus(const int status)
 static int simple_get_status(struct dvb_frontend *fe, u32 *status)
 {
 	struct tuner_simple_priv *priv = fe->tuner_priv;
-	int tuner_status = tuner_read_status(fe);
+	int tuner_status;
+
+	if (priv->i2c_props.adap == NULL)
+		return -EINVAL;
+
+	tuner_status = tuner_read_status(fe);
 
 	*status = 0;
 
@@ -166,7 +171,12 @@ static int simple_get_status(struct dvb_frontend *fe, u32 *status)
 static int simple_get_rf_strength(struct dvb_frontend *fe, u16 *strength)
 {
 	struct tuner_simple_priv *priv = fe->tuner_priv;
-	int signal = tuner_signal(tuner_read_status(fe));
+	int signal;
+
+	if (priv->i2c_props.adap == NULL)
+		return -EINVAL;
+
+	signal = tuner_signal(tuner_read_status(fe));
 
 	*strength = signal;
 
@@ -685,6 +695,9 @@ static int simple_set_params(struct dvb_frontend *fe,
 	struct tuner_simple_priv *priv = fe->tuner_priv;
 	int ret = -EINVAL;
 
+	if (priv->i2c_props.adap == NULL)
+		return -EINVAL;
+
 	switch (params->mode) {
 	case V4L2_TUNER_RADIO:
 		ret = simple_set_radio_freq(fe, params);