Re: [U-Boot] [PATCH] fsl: verify writes to the MAC address EEPROM

Dear Timur Tabi,

In message 1280772203-8859-1-git-send-email-timur@freescale.com you wrote:

Update the code which writes to the on-board EEPROM so that it can detect if the write failed because the EEPROM is write-protected. Most of the 8xxx-class Freescale reference boards use an AT24C02 EEPROM to store MAC addresses and similar information. With this patch, if the EEPROM is protected, the "mac save" command will display an error message indicating that the write has not succeeded.

Signed-off-by: Timur Tabi timur@freescale.com

board/freescale/common/sys_eeprom.c | 18 +++++++++++++++++-

...

• /*

• * The AT24C02 datasheet says that data can only be written in page
  

• * mode, which means 8 bytes at a time, and it takes up to 5ms to
  

• * complete a given write.
  

• */
  

  for (i = 0, p = &e; i < sizeof(e); i += 8, p += 8) { ret = i2c_write(CONFIG_SYS_I2C_EEPROM_ADDR, i, CONFIG_SYS_I2C_EEPROM_ADDR_LEN, p, min((sizeof(e) - i), 8));

@@ -233,12 +238,23 @@ static int prog_eeprom(void) udelay(5000); /* 5ms write cycle timing */ }

• if (!ret) {

• /* Verify the write by reading back the EEPROM and comparing */
  

• struct eeprom e2;
  

• ret = i2c_read(CONFIG_SYS_I2C_EEPROM_ADDR, 0,
  

• 	CONFIG_SYS_I2C_EEPROM_ADDR_LEN, (void *)&e2, sizeof(e2));
  

• if (!ret && memcmp(&e, &e2, sizeof(e)))
  

• 	ret = -1;
  

• }

Why is this i2c_read() needed or actually useful? Should the error return code from the i2c_write() above not be sufficient indication that the writing failed? If that was the case, then some other parts of the code need fixing.

Best regards,

Wolfgang Denk