On Thu, Sep 25, 2014 at 11:34 AM, Chris Fryer <[email protected]> wrote:
> I now see that there is an open patch set to enable/disable flash
> protection on kinetis (http://openocd.zylin.com/#/c/2051/) with the last
> change in July.
>
> I don't need to recover my broken board but would appreciate some
> guidance as to the state of these changes.
>
> Can I just pull this change set and expect to be able to
> protect/unprotect devices? or is it likely that I'll break more parts?
>
Protection and securing are two different things. The patch you're
referring to implements flash write protection. The mdm mass_erase command
deals with unsecuring (read-out protection). If you have problems
connecting to the chip, it is probably because the chip is in a secured
state. My own (very limited) experience with Kinetis parts, K40 and KL25Z
(?), tells me that the handling of chip securing and unsecuring is highly
unreliable. I've managed to lose access to the chip semi-permanently simply
by erasing and trying to reprogram it (which as far as I can tell is by
design... horribly bad design). A secured chip behaves erratically and the
attempt to recover it has a voodoo feeling to it.
I don't think the write protection patch would make the situation neither
better nor worse.
Not even J-Link Commander can reliably recover a locked K40 so I tend to
blame the chip design rather than OpenOCD. I've managed at least once to
unlock it using a combination of J-Link Commander and OpenOCD in unknown
combinations.
If you have any insights on how to handle the securing "feature" robustly
on these chips, patches are welcome.
/Andreas
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