V4L/DVB (13976): [STV090x] Added mutex protection around tuner I2C access.

With this change it is possible to have the same I2C address for both tuners.
Signed-off-by: Andreas Regel <andreas.regel@gmx.de>
Signed-off-by: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/dvb/frontends/stv090x.c

@@ -758,6 +758,9 @@ static int stv090x_i2c_gate_ctrl(struct dvb_frontend *fe, int enable)
 	struct stv090x_state *state = fe->demodulator_priv;
 	u32 reg;
 
+	if (enable)
+		mutex_lock(&state->internal->tuner_lock);
+
 	reg = STV090x_READ_DEMOD(state, I2CRPT);
 	if (enable) {
 		dprintk(FE_DEBUG, 1, "Enable Gate");
@@ -771,9 +774,14 @@ static int stv090x_i2c_gate_ctrl(struct dvb_frontend *fe, int enable)
 		if ((STV090x_WRITE_DEMOD(state, I2CRPT, reg)) < 0)
 			goto err;
 	}
+
+	if (!enable)
+		mutex_unlock(&state->internal->tuner_lock);
+
 	return 0;
 err:
 	dprintk(FE_ERROR, 1, "I/O error");
+	mutex_unlock(&state->internal->tuner_lock);
 	return -1;
 }
 
@@ -4439,6 +4447,7 @@ struct dvb_frontend *stv090x_attach(const struct stv090x_config *config,
 	}
 
 	mutex_init(&state->internal->demod_lock);
+	mutex_init(&state->internal->tuner_lock);
 
 	if (stv090x_sleep(&state->frontend) < 0) {
 		dprintk(FE_ERROR, 1, "Error putting device to sleep");

drivers/media/dvb/frontends/stv090x_priv.h

@@ -235,6 +235,7 @@ struct stv090x_internal {
 	u8			i2c_addr;
 
 	struct mutex		demod_lock; /* Lock access to shared register */
+	struct mutex		tuner_lock; /* Lock access to tuners */
 	s32			mclk; /* Masterclock Divider factor */
 	u32			dev_ver;