In message 29f916510601080721vd20b512u819ee9bce7ad1408@mail.gmail.com you wrote:
- Does u-boot lock the block on which it resides by default ?
Not by default, but you can inplement in your flah driver whichever features you like.
I mean the sector /erase block on which u-boot is there, it will be locked using the block lock bit by default ?
Remember that only few flash chips provide such hardware locking, and that some boards implement even other ways of write protection of parts of or of the whole flash device.
- The flash content changing has to work in block sizes erase -
modify - write cyecles only ??
No. You can write single bytes (as long as you are only changing '1' bits to '0').
Reason for all this is that we have few boards on which u-boot is getting corrupted (on flash image corruption itself). And so am wondering even if its a noise issue, how can it first cause an unlock of sector before write.
Normally the flash is not hardare write protected, and if your hardware designer used flash chips which can be corrupted for example by just writing arbitrary data to a sequential address range you may easily see such corruption. There is a very good reason why AMD flash chips require a specific programming sequence which must be written in a certain sequence to certain non-consequitive addresses.
Best regards,
Wolfgang Denk