diff --git a/board/gdsys/405ep/iocon.c b/board/gdsys/405ep/iocon.c
index 7a98e41..079dfb2 100644
--- a/board/gdsys/405ep/iocon.c
+++ b/board/gdsys/405ep/iocon.c
@@ -15,6 +15,7 @@
 #include "405ep.h"
 #include <gdsys_fpga.h>
 
+#include "../common/dp501.h"
 #include "../common/osd.h"
 #include "../common/mclink.h"
 
@@ -98,6 +99,8 @@ enum {
 unsigned int mclink_fpgacount;
 struct ihs_fpga *fpga_ptr[] = CONFIG_SYS_FPGA_PTR;
 
+int dp501_i2c[] = CONFIG_SYS_DP501_I2C;
+
 static int setup_88e1518(const char *bus, unsigned char addr);
 
 int fpga_set_reg(u32 fpga, u16 *reg, off_t regoff, u16 data)
@@ -371,9 +374,18 @@ int last_stage_init(void)
 	u16 fpga_features;
 	int feature_carrier_speed = fpga_features & (1<<4);
 	bool ch0_rgmii2_present = false;
+	int old_bus = i2c_get_bus_num();
 
 	FPGA_GET_REG(0, fpga_features, &fpga_features);
 
+	/* Turn on Parade DP501 */
+	pca9698_direction_output(0x20, 9, 1);
+	udelay(500000);
+
+	i2c_set_bus_num(dp501_i2c[0]);
+	dp501_powerup(0x08);
+	i2c_set_bus_num(old_bus);
+
 	if (!legacy)
 		ch0_rgmii2_present = !pca9698_get_value(0x20, 30);
 
diff --git a/board/gdsys/common/Makefile b/board/gdsys/common/Makefile
index fb841e0..7f8b427 100644
--- a/board/gdsys/common/Makefile
+++ b/board/gdsys/common/Makefile
@@ -8,6 +8,6 @@
 obj-$(CONFIG_SYS_FPGA_COMMON) += fpga.o
 obj-$(CONFIG_IO) += miiphybb.o
 obj-$(CONFIG_IO64) += miiphybb.o
-obj-$(CONFIG_IOCON) += osd.o mclink.o
+obj-$(CONFIG_IOCON) += osd.o mclink.o dp501.o
 obj-$(CONFIG_DLVISION_10G) += osd.o
 obj-$(CONFIG_CONTROLCENTERD) += dp501.o
diff --git a/board/gdsys/common/dp501.c b/board/gdsys/common/dp501.c
index 52f3ea1..e00e589 100644
--- a/board/gdsys/common/dp501.c
+++ b/board/gdsys/common/dp501.c
@@ -60,8 +60,31 @@ void dp501_powerup(u8 addr)
 	i2c_reg_write(addr, 0x71, 0x20); /* Enable Aux burst write */
 	dp501_setbits(addr, 0x78, 0x30); /* Disable HPD2 IRQ */
 	dp501_clrbits(addr, 0x2f, 0x40); /* Link FIFO reset selection */
+
+#ifdef CONFIG_SYS_DP501_VCAPCTRL0
+	i2c_reg_write(addr, 0x24, CONFIG_SYS_DP501_VCAPCTRL0);
+#else
 	i2c_reg_write(addr, 0x24, 0xc0); /* SDR mode 0, ext. H/VSYNC */
+#endif
+
+#ifdef CONFIG_SYS_DP501_DIFFERENTIAL
+	i2c_reg_write(addr + 2, 0x24, 0x10); /* clock input differential */
+	i2c_reg_write(addr + 2, 0x25, 0x04);
+	i2c_reg_write(addr + 2, 0x26, 0x10);
+#else
 	i2c_reg_write(addr + 2, 0x24, 0x02); /* clock input single ended */
+#endif
+
+	i2c_reg_write(addr + 2, 0x00, 0x18); /* driving strength */
+	i2c_reg_write(addr + 2, 0x03, 0x06); /* driving strength */
+	i2c_reg_write(addr, 0x2c, 0x00); /* configure N value */
+	i2c_reg_write(addr, 0x2d, 0x00); /* configure N value */
+	i2c_reg_write(addr, 0x2e, 0x0c); /* configure N value */
+	i2c_reg_write(addr, 0x76, 0xff); /* clear all interrupt */
+	dp501_setbits(addr, 0x78, 0x03); /* clear all interrupt */
+	i2c_reg_write(addr, 0x75, 0xf8); /* aux channel reset */
+	i2c_reg_write(addr, 0x75, 0x00); /* clear aux channel reset */
+	i2c_reg_write(addr, 0x87, 0x70); /* set retry counter as 7 */
 
 	if (dp501_detect_cable_adapter(addr)) {
 		printf("DVI/HDMI cable adapter detected\n");
@@ -69,16 +92,6 @@ void dp501_powerup(u8 addr)
 		dp501_clrbits(addr, 0x00, 0x08); /* DVI/HDMI HDCP operation */
 	} else {
 		printf("no DVI/HDMI cable adapter detected\n");
-		i2c_reg_write(addr + 2, 0x00, 0x18); /* driving strength */
-		i2c_reg_write(addr + 2, 0x03, 0x06); /* driving strength */
-		i2c_reg_write(addr, 0x2c, 0x00); /* configure N value */
-		i2c_reg_write(addr, 0x2d, 0x00); /* configure N value */
-		i2c_reg_write(addr, 0x2e, 0x0c); /* configure N value */
-		i2c_reg_write(addr, 0x76, 0xff); /* clear all interrupt */
-		dp501_setbits(addr, 0x78, 0x03); /* clear all interrupt */
-		i2c_reg_write(addr, 0x75, 0xf8); /* aux channel reset */
-		i2c_reg_write(addr, 0x75, 0x00); /* clear aux channel reset */
-		i2c_reg_write(addr, 0x87, 0x70); /* set retry counter as 7 */
 		dp501_setbits(addr, 0x00, 0x08); /* for DP HDCP operation */
 
 		dp501_link_training(addr);
diff --git a/board/gdsys/common/osd.c b/board/gdsys/common/osd.c
index c49cd9a..0290949 100644
--- a/board/gdsys/common/osd.c
+++ b/board/gdsys/common/osd.c
@@ -58,45 +58,12 @@ unsigned int max_osd_screen = CONFIG_SYS_OSD_SCREENS - 1;
 int ch7301_i2c[] = CONFIG_SYS_CH7301_I2C;
 #endif
 
-#if defined(CONFIG_SYS_ICS8N3QV01) || defined(CONFIG_SYS_SIL1178)
-static void fpga_iic_write(unsigned screen, u8 slave, u8 reg, u8 data)
-{
-	u16 val;
-
-	do {
-		FPGA_GET_REG(screen, extended_interrupt, &val);
-	} while (val & (1 << 12));
-
-	FPGA_SET_REG(screen, i2c.write_mailbox_ext, reg | (data << 8));
-	FPGA_SET_REG(screen, i2c.write_mailbox, 0xc400 | (slave << 1));
-}
-
-static u8 fpga_iic_read(unsigned screen, u8 slave, u8 reg)
-{
-	unsigned int ctr = 0;
-	u16 val;
-
-	do {
-		FPGA_GET_REG(screen, extended_interrupt, &val);
-	} while (val & (1 << 12));
-
-	FPGA_SET_REG(screen, extended_interrupt, 1 << 14);
-	FPGA_SET_REG(screen, i2c.write_mailbox_ext, reg);
-	FPGA_SET_REG(screen, i2c.write_mailbox, 0xc000 | (slave << 1));
-
-	FPGA_GET_REG(screen, extended_interrupt, &val);
-	while (!(val & (1 << 14))) {
-		udelay(100000);
-		if (ctr++ > 5) {
-			printf("iic receive timeout\n");
-			break;
-		}
-		FPGA_GET_REG(screen, extended_interrupt, &val);
-	}
+#ifdef CONFIG_SYS_ICS8N3QV01
+int ics8n3qv01_i2c[] = CONFIG_SYS_ICS8N3QV01_I2C;
+#endif
 
-	FPGA_GET_REG(screen, i2c.read_mailbox_ext, &val);
-	return val >> 8;
-}
+#ifdef CONFIG_SYS_SIL1178
+int sil1178_i2c[] = CONFIG_SYS_SIL1178_I2C;
 #endif
 
 #ifdef CONFIG_SYS_MPC92469AC
@@ -153,7 +120,7 @@ static void mpc92469ac_set(unsigned screen, unsigned int fout)
 
 #ifdef CONFIG_SYS_ICS8N3QV01
 
-static unsigned int ics8n3qv01_get_fout_calc(unsigned screen, unsigned index)
+static unsigned int ics8n3qv01_get_fout_calc(unsigned index)
 {
 	unsigned long long n;
 	unsigned long long mint;
@@ -164,11 +131,11 @@ static unsigned int ics8n3qv01_get_fout_calc(unsigned screen, unsigned index)
 	if (index > 3)
 		return 0;
 
-	reg_a = fpga_iic_read(screen, ICS8N3QV01_I2C_ADDR, 0 + index);
-	reg_b = fpga_iic_read(screen, ICS8N3QV01_I2C_ADDR, 4 + index);
-	reg_c = fpga_iic_read(screen, ICS8N3QV01_I2C_ADDR, 8 + index);
-	reg_d = fpga_iic_read(screen, ICS8N3QV01_I2C_ADDR, 12 + index);
-	reg_f = fpga_iic_read(screen, ICS8N3QV01_I2C_ADDR, 20 + index);
+	reg_a = i2c_reg_read(ICS8N3QV01_I2C_ADDR, 0 + index);
+	reg_b = i2c_reg_read(ICS8N3QV01_I2C_ADDR, 4 + index);
+	reg_c = i2c_reg_read(ICS8N3QV01_I2C_ADDR, 8 + index);
+	reg_d = i2c_reg_read(ICS8N3QV01_I2C_ADDR, 12 + index);
+	reg_f = i2c_reg_read(ICS8N3QV01_I2C_ADDR, 20 + index);
 
 	mint = ((reg_a >> 1) & 0x1f) | (reg_f & 0x20);
 	mfrac = ((reg_a & 0x01) << 17) | (reg_b << 9) | (reg_c << 1)
@@ -216,7 +183,7 @@ static void ics8n3qv01_calc_parameters(unsigned int fout,
 	*_n = n;
 }
 
-static void ics8n3qv01_set(unsigned screen, unsigned int fout)
+static void ics8n3qv01_set(unsigned int fout)
 {
 	unsigned int n;
 	unsigned int mint;
@@ -226,7 +193,7 @@ static void ics8n3qv01_set(unsigned screen, unsigned int fout)
 	long long off_ppm;
 	u8 reg0, reg4, reg8, reg12, reg18, reg20;
 
-	fout_calc = ics8n3qv01_get_fout_calc(screen, 1);
+	fout_calc = ics8n3qv01_get_fout_calc(1);
 	off_ppm = (fout_calc - ICS8N3QV01_F_DEFAULT_1) * 1000000
 		  / ICS8N3QV01_F_DEFAULT_1;
 	printf("       PLL is off by %lld ppm\n", off_ppm);
@@ -234,28 +201,28 @@ static void ics8n3qv01_set(unsigned screen, unsigned int fout)
 		    / ICS8N3QV01_F_DEFAULT_1;
 	ics8n3qv01_calc_parameters(fout_prog, &mint, &mfrac, &n);
 
-	reg0 = fpga_iic_read(screen, ICS8N3QV01_I2C_ADDR, 0) & 0xc0;
+	reg0 = i2c_reg_read(ICS8N3QV01_I2C_ADDR, 0) & 0xc0;
 	reg0 |= (mint & 0x1f) << 1;
 	reg0 |= (mfrac >> 17) & 0x01;
-	fpga_iic_write(screen, ICS8N3QV01_I2C_ADDR, 0, reg0);
+	i2c_reg_write(ICS8N3QV01_I2C_ADDR, 0, reg0);
 
 	reg4 = mfrac >> 9;
-	fpga_iic_write(screen, ICS8N3QV01_I2C_ADDR, 4, reg4);
+	i2c_reg_write(ICS8N3QV01_I2C_ADDR, 4, reg4);
 
 	reg8 = mfrac >> 1;
-	fpga_iic_write(screen, ICS8N3QV01_I2C_ADDR, 8, reg8);
+	i2c_reg_write(ICS8N3QV01_I2C_ADDR, 8, reg8);
 
 	reg12 = mfrac << 7;
 	reg12 |= n & 0x7f;
-	fpga_iic_write(screen, ICS8N3QV01_I2C_ADDR, 12, reg12);
+	i2c_reg_write(ICS8N3QV01_I2C_ADDR, 12, reg12);
 
-	reg18 = fpga_iic_read(screen, ICS8N3QV01_I2C_ADDR, 18) & 0x03;
+	reg18 = i2c_reg_read(ICS8N3QV01_I2C_ADDR, 18) & 0x03;
 	reg18 |= 0x20;
-	fpga_iic_write(screen, ICS8N3QV01_I2C_ADDR, 18, reg18);
+	i2c_reg_write(ICS8N3QV01_I2C_ADDR, 18, reg18);
 
-	reg20 = fpga_iic_read(screen, ICS8N3QV01_I2C_ADDR, 20) & 0x1f;
+	reg20 = i2c_reg_read(ICS8N3QV01_I2C_ADDR, 20) & 0x1f;
 	reg20 |= mint & (1 << 5);
-	fpga_iic_write(screen, ICS8N3QV01_I2C_ADDR, 20, reg20);
+	i2c_reg_write(ICS8N3QV01_I2C_ADDR, 20, reg20);
 }
 #endif
 
@@ -315,9 +282,7 @@ int osd_probe(unsigned screen)
 	u16 version;
 	u16 features;
 	u8 value;
-#ifdef CONFIG_SYS_CH7301
 	int old_bus = i2c_get_bus_num();
-#endif
 
 	FPGA_GET_REG(0, osd.version, &version);
 	FPGA_GET_REG(0, osd.features, &features);
@@ -345,7 +310,6 @@ int osd_probe(unsigned screen)
 	i2c_reg_write(CH7301_I2C_ADDR, CH7301_TPF, 0x60);
 	i2c_reg_write(CH7301_I2C_ADDR, CH7301_DC, 0x09);
 	i2c_reg_write(CH7301_I2C_ADDR, CH7301_PM, 0xc0);
-	i2c_set_bus_num(old_bus);
 #endif
 
 #ifdef CONFIG_SYS_MPC92469AC
@@ -353,26 +317,29 @@ int osd_probe(unsigned screen)
 #endif
 
 #ifdef CONFIG_SYS_ICS8N3QV01
-	ics8n3qv01_set(screen, PIXCLK_640_480_60);
+	i2c_set_bus_num(ics8n3qv01_i2c[screen]);
+	ics8n3qv01_set(PIXCLK_640_480_60);
 #endif
 
 #ifdef CONFIG_SYS_SIL1178
-	value = fpga_iic_read(screen, SIL1178_SLAVE_I2C_ADDRESS, 0x02);
+	i2c_set_bus_num(sil1178_i2c[screen]);
+	value = i2c_reg_read(SIL1178_SLAVE_I2C_ADDRESS, 0x02);
 	if (value != 0x06) {
-		printf("       Probing CH7301 SIL1178, DEV_IDL %02x\n", value);
+		printf("       Probing SIL1178, DEV_IDL %02x\n", value);
+		i2c_set_bus_num(old_bus);
 		return -1;
 	}
 	/* magic initialization sequence adapted from datasheet */
-	fpga_iic_write(screen, SIL1178_SLAVE_I2C_ADDRESS, 0x08, 0x36);
-	fpga_iic_write(screen, SIL1178_MASTER_I2C_ADDRESS, 0x0f, 0x44);
-	fpga_iic_write(screen, SIL1178_MASTER_I2C_ADDRESS, 0x0f, 0x4c);
-	fpga_iic_write(screen, SIL1178_MASTER_I2C_ADDRESS, 0x0e, 0x10);
-	fpga_iic_write(screen, SIL1178_MASTER_I2C_ADDRESS, 0x0a, 0x80);
-	fpga_iic_write(screen, SIL1178_MASTER_I2C_ADDRESS, 0x09, 0x30);
-	fpga_iic_write(screen, SIL1178_MASTER_I2C_ADDRESS, 0x0c, 0x89);
-	fpga_iic_write(screen, SIL1178_MASTER_I2C_ADDRESS, 0x0d, 0x60);
-	fpga_iic_write(screen, SIL1178_MASTER_I2C_ADDRESS, 0x08, 0x36);
-	fpga_iic_write(screen, SIL1178_MASTER_I2C_ADDRESS, 0x08, 0x37);
+	i2c_reg_write(SIL1178_SLAVE_I2C_ADDRESS, 0x08, 0x36);
+	i2c_reg_write(SIL1178_MASTER_I2C_ADDRESS, 0x0f, 0x44);
+	i2c_reg_write(SIL1178_MASTER_I2C_ADDRESS, 0x0f, 0x4c);
+	i2c_reg_write(SIL1178_MASTER_I2C_ADDRESS, 0x0e, 0x10);
+	i2c_reg_write(SIL1178_MASTER_I2C_ADDRESS, 0x0a, 0x80);
+	i2c_reg_write(SIL1178_MASTER_I2C_ADDRESS, 0x09, 0x30);
+	i2c_reg_write(SIL1178_MASTER_I2C_ADDRESS, 0x0c, 0x89);
+	i2c_reg_write(SIL1178_MASTER_I2C_ADDRESS, 0x0d, 0x60);
+	i2c_reg_write(SIL1178_MASTER_I2C_ADDRESS, 0x08, 0x36);
+	i2c_reg_write(SIL1178_MASTER_I2C_ADDRESS, 0x08, 0x37);
 #endif
 
 	FPGA_SET_REG(screen, videocontrol, 0x0002);
@@ -385,6 +352,8 @@ int osd_probe(unsigned screen)
 	if (screen > max_osd_screen)
 		max_osd_screen = screen;
 
+	i2c_set_bus_num(old_bus);
+
 	return 0;
 }
 
diff --git a/include/configs/iocon.h b/include/configs/iocon.h
index f36c2a3..5636f38 100644
--- a/include/configs/iocon.h
+++ b/include/configs/iocon.h
@@ -121,7 +121,9 @@
 #define CONFIG_SYS_I2C_SOFT_SPEED_4		50000
 #define CONFIG_SYS_I2C_SOFT_SLAVE_4		0x7F
 
+#define CONFIG_SYS_ICS8N3QV01_I2C		{1, 2, 3, 4}
 #define CONFIG_SYS_CH7301_I2C			{1, 2, 3, 4}
+#define CONFIG_SYS_DP501_I2C			{1, 2, 3, 4}
 
 #ifndef __ASSEMBLY__
 void fpga_gpio_set(unsigned int bus, int pin);
@@ -146,6 +148,8 @@ int fpga_gpio_get(unsigned int bus, int pin);
 			fpga_gpio_set(I2C_ADAP_HWNR, 0x0020); \
 		else \
 			fpga_gpio_clear(I2C_ADAP_HWNR, 0x0020); \
+		while (!!fpga_gpio_get(I2C_ADAP_HWNR, 0x0020) != !!bit) \
+			; \
 	} while (0)
 #define I2C_DELAY	udelay(25)	/* 1/4 I2C clock duration */
 
@@ -153,7 +157,6 @@ int fpga_gpio_get(unsigned int bus, int pin);
  * OSD hardware
  */
 #define CONFIG_SYS_MPC92469AC
-#define CONFIG_SYS_CH7301
 
 /*
  * FLASH organization
@@ -282,9 +285,11 @@ int fpga_gpio_get(unsigned int bus, int pin);
 /*
  * OSD Setup
  */
+#define CONFIG_SYS_ICS8N3QV01
 #define CONFIG_SYS_MPC92469AC
-#define CONFIG_SYS_CH7301
 #define CONFIG_SYS_OSD_SCREENS		1
+#define CONFIG_SYS_DP501_DIFFERENTIAL
+#define CONFIG_SYS_DP501_VCAPCTRL0	0x01 /* DDR mode 0, DE for H/VSYNC */
 
 #define CONFIG_BITBANGMII		/* bit-bang MII PHY management */
 #define CONFIG_BITBANGMII_MULTI
