board: ti: common: board_detect: Do 1byte address checks first.

Do 1 byte address checks first prior to doing 2 byte address checks.
When performing 2 byte addressing on 1 byte addressing eeprom, the
second byte is taken in as a write operation and ends up erasing the
eeprom region we want to preserve.

While we could have theoretically handled this by ensuring the write
protect of the eeproms are properly managed, this is not true in case
where board are updated with 1 byte eeproms to handle supply status.

Flipping the checks by checking for 1 byte addressing prior to 2 byte
addressing check prevents this problem at the minor cost of additional
overhead for boards with 2 byte addressing eeproms.

Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

board/ti/common/board_detect.c

@@ -103,14 +103,14 @@ static int __maybe_unused ti_i2c_eeprom_get(int bus_addr, int dev_addr,
 	/*
 	 * Read the header first then only read the other contents.
 	 */
-	rc = i2c_set_chip_offset_len(dev, 2);
+	rc = i2c_set_chip_offset_len(dev, 1);
 	if (rc)
 		return rc;
 
 	/*
 	 * Skip checking result here since this could be a valid i2c read fail
-	 * on some boards that use 1 byte addressing.
-	 * We must allow for fall through to check the data if 1 byte
+	 * on some boards that use 2 byte addressing.
+	 * We must allow for fall through to check the data if 2 byte
 	 * addressing works
 	 */
 	(void)dm_i2c_read(dev, 0, (uint8_t *)&hdr_read, 4);
@@ -119,9 +119,9 @@ static int __maybe_unused ti_i2c_eeprom_get(int bus_addr, int dev_addr,
 	if (hdr_read != header) {
 		/*
 		 * read the eeprom header using i2c again, but use only a
-		 * 1 byte address (some legacy boards need this..)
+		 * 2 byte address (some newer boards need this..)
 		 */
-		rc = i2c_set_chip_offset_len(dev, 1);
+		rc = i2c_set_chip_offset_len(dev, 2);
 		if (rc)
 			return rc;
 
@@ -146,12 +146,12 @@ static int __maybe_unused ti_i2c_eeprom_get(int bus_addr, int dev_addr,
 	/*
 	 * Read the header first then only read the other contents.
 	 */
-	byte = 2;
+	byte = 1;
 
 	/*
 	 * Skip checking result here since this could be a valid i2c read fail
-	 * on some boards that use 1 byte addressing.
-	 * We must allow for fall through to check the data if 1 byte
+	 * on some boards that use 2 byte addressing.
+	 * We must allow for fall through to check the data if 2 byte
 	 * addressing works
 	 */
 	(void)i2c_read(dev_addr, 0x0, byte, (uint8_t *)&hdr_read, 4);
@@ -160,9 +160,9 @@ static int __maybe_unused ti_i2c_eeprom_get(int bus_addr, int dev_addr,
 	if (hdr_read != header) {
 		/*
 		 * read the eeprom header using i2c again, but use only a
-		 * 1 byte address (some legacy boards need this..)
+		 * 2 byte address (some newer boards need this..)
 		 */
-		byte = 1;
+		byte = 2;
 		rc = i2c_read(dev_addr, 0x0, byte, (uint8_t *)&hdr_read,
 			      4);
 		if (rc)