[avrdude-dev] [patch #9507] Fix UPDI chip erase

[Jan Egil Ruud]

Follow-up Comment #4, patch #9507 (project avrdude):

With the new UPDI AVR's the locking concept has changed. Previously, on old
AVR's, when you locked a device you just made the flash unreadable. With the
new UPDI AVR's you lock down the whole chip, including the ability to read the
signature. There are datasheets that state otherwise, but that is wrong and
will be corrected (as soon as possible...).
One of the things you can read from a locked device is the SIB (System
Information Block). The first 7 bytes of the SIB is Family_ID, which for all
the new UPDI tiny's are 0x74 0x69 0x6e 0x79 0x41 0x56 0x52 => tinyAVR. Not a
really good replacement for the current signature verification.
The CMD3_SIGN_ON command will return the first four bytes of the SIB, in this
case "tiny".

So, my suggestion is:
We could do a compare on the CMD3_SIGN_ON response, but if you have selected a
UPDI device and CMD3_ENTER_PROG_MODE is responded with RSP3_FAIL_OCD_LOCKED,
avrdude should continue and check if the user have specified "-e" (chiperase).

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