Index: v4l-dvb/linux/drivers/media/dvb/frontends/mt312.c
===================================================================
--- v4l-dvb.orig/linux/drivers/media/dvb/frontends/mt312.c
+++ v4l-dvb/linux/drivers/media/dvb/frontends/mt312.c
@@ -420,10 +420,11 @@ static int mt312_set_voltage(struct dvb_
 	struct mt312_state *state = fe->demodulator_priv;
 	const u8 volt_tab[3] = { 0x00, 0x40, 0x00 };
 
+	u8 flip_bits = state->config->voltage_inverted ? 0x40 : 0x00;
 	if (v > SEC_VOLTAGE_OFF)
 		return -EINVAL;
 
-	return mt312_writereg(state, DISEQC_MODE, volt_tab[v]);
+	return mt312_writereg(state, DISEQC_MODE, volt_tab[v] ^ flip_bits);
 }
 
 static int mt312_read_status(struct dvb_frontend *fe, fe_status_t *s)
Index: v4l-dvb/linux/drivers/media/dvb/frontends/mt312.h
===================================================================
--- v4l-dvb.orig/linux/drivers/media/dvb/frontends/mt312.h
+++ v4l-dvb/linux/drivers/media/dvb/frontends/mt312.h
@@ -31,6 +31,9 @@
 struct mt312_config {
 	/* the demodulator's i2c address */
 	u8 demod_address;
+
+	/* inverted voltage setting */
+	int voltage_inverted:1;
 };
 
 #if defined(CONFIG_DVB_MT312) || (defined(CONFIG_DVB_MT312_MODULE) && defined(MODULE))