Hello u-boot users,
We are in the state of porting u-boot to our PPC405 based custom board and have to decide whether to store the environment in flash or in a serial EEPROM.
Yes, I know that this has been discussed recently and the recommendation is to store the environment in flash, but:
- storing the environment in flash with redundancy means to spend 2 (128 kB in our case) sectors for approx. 1 kB of environment data.
- the problem described for EEPROM storage should also appear when storing other data in EEPROM's (e.g. SPD data etc.) and thus a proper solution should be found for EEPROM storage.
- The solution provided in common/soft_i2c.c sets the SDA line to 1 and issues 9 cycles on the SCL line. Is this an undefined I2C pattern causing a reset on the I2C bus (which is not specified in the I2C specification)? Why is it not sufficient to issue a simple Start/Stop sequence on the bus?
- Are there conditions known to cause similar effects with flash chips as described for EEPROM devices? Could power loss or similar conditions when writing environment sectors cause a flash device to destroy other sectors than the just written one?
Any pointer/comments would be appreciated.
Best regards,
Thomas Schäfer
____________________________________
Kontron Modular Computers GmbH
Konrad-Zuse-Str. 9 66115 Saarbrücken
Tel.: + 49 (0)681 / 95916 - 203 Fax: + 49 (0)681 / 95916 - 100 E-mail: thomas.schaefer@kontron.com