via: Rationalize vt1636 detection

The code was ugly and didn't check whether i2c operations were succeeding;
make it a little better.

Cc: ScottFang@viatech.com.cn
Cc: JosephChan@via.com.tw
Cc: Harald Welte <laforge@gnumonks.org>
Acked-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

drivers/video/via/vt1636.c

@@ -167,26 +167,20 @@ bool viafb_lvds_identify_vt1636(u8 i2c_adapter)
 
 	/* Sense VT1636 LVDS Transmiter */
 	viaparinfo->chip_info->lvds_chip_info.lvds_chip_slave_addr =
-	VT1636_LVDS_I2C_ADDR;
+		VT1636_LVDS_I2C_ADDR;
 
 	/* Check vendor ID first: */
-	viafb_i2c_readbyte(i2c_adapter,
-			   (u8) viaparinfo->chip_info->lvds_chip_info.lvds_chip_slave_addr,
-			   0x00, &Buffer[0]);
-	viafb_i2c_readbyte(i2c_adapter,
-			   (u8) viaparinfo->chip_info->lvds_chip_info.lvds_chip_slave_addr,
-			   0x01, &Buffer[1]);
+	if (viafb_i2c_readbyte(i2c_adapter, VT1636_LVDS_I2C_ADDR,
+					0x00, &Buffer[0]))
+		return false;
+	viafb_i2c_readbyte(i2c_adapter, VT1636_LVDS_I2C_ADDR, 0x01, &Buffer[1]);
 
 	if (!((Buffer[0] == 0x06) && (Buffer[1] == 0x11)))
 		return false;
 
 	/* Check Chip ID: */
-	viafb_i2c_readbyte(i2c_adapter,
-			   (u8) viaparinfo->chip_info->lvds_chip_info.lvds_chip_slave_addr,
-			   0x02, &Buffer[0]);
-	viafb_i2c_readbyte(i2c_adapter,
-			   (u8) viaparinfo->chip_info->lvds_chip_info.lvds_chip_slave_addr,
-			   0x03, &Buffer[1]);
+	viafb_i2c_readbyte(i2c_adapter, VT1636_LVDS_I2C_ADDR, 0x02, &Buffer[0]);
+	viafb_i2c_readbyte(i2c_adapter, VT1636_LVDS_I2C_ADDR, 0x03, &Buffer[1]);
 	if ((Buffer[0] == 0x45) && (Buffer[1] == 0x33)) {
 		viaparinfo->chip_info->lvds_chip_info.lvds_chip_name =
 			VT1636_LVDS;