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 <[e-mail]>
Signed-off-by: Manu Abraham <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/dvb/frontends/stv090x.c

···
 	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");
···
 		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;
 }
 
···
 	}
 
 	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

···
 	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;