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−There is a tiny (120 bytes SREC file) program called flash-boot-wa that was
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−written in the spring of 2017 for the purpose of working around a problem that
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−happened on only one first-batch FCDEV3B board and never happened on any other
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−board - but Murphy's law had it that this one troubled board just had to be the
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−one on which my (Mother Mychaela's) very initial development and bring-up work
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−was done.
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−
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−The defect exhibited on that one board was as follows: it had no problem booting
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−serially (fc-iram, fc-loadtool, fc-xram) and it had no problem booting from
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−flash in mode 0 (see the Flash-boot-modes article in the freecalypso-docs
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−repository), but booting from flash in mode 1 (the flash boot mode used by
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−FC Magnetite, which is our primary firmware) was troubled.  The exact failure
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−mode and the root cause were never solved, but the issue most likely involved
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−the watchdog reset in some way (it occurs as part of flash boot mode 1 but not
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−in mode 0 and not in serial downloading), and because Calypso's FDP output goes
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−low during watchdog reset (or at least TI's CAL000 document says so), it is
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−plausible that the root cause involved the Spansion flash chip getting unhappy
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−as a result of being jerked with extra resets which don't meet its reset timing
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−requirements.
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−
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−Our new FCDEV3B V2 boards no longer use Calypso's FDP output (it is left
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−unconnected) and feature a new flash reset circuit of our own design that meets
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−the reset timing requirements of our Spansion flash chip, hence the flash boot
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−problem seen on that one FCDEV3B S/N 001 board is not expected to recur on any
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−of our current or future boards.  However, our little flash-boot-wa program is
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−kept around: removing a previously-released 120-byte program for no good reason
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−is not the way of FOSS.
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−
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−This flash-boot-wa program is loaded serially via fc-iram; it disables the boot
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−ROM and jumps to address 0 (the opposite of what we do in compalstage for Mot
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−C1xx phones), thereby indirectly booting the made-for-boot-mode-1 firmware image
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−in the flash.  The intended usage was as follows:
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−
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−fc-iram -h fcfam /dev/ttyXXX /opt/freecalypso/target-bin/flash-boot-wa.srec rvinterf
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−
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−It is also worth noting that fc-iram has been extended to support second program
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−invokation just like fc-xram (used in the invokation line above) just for this
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−peculiar use case.  The flash-boot-wa.srec helper can also be booted via
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−fc-xram.