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fc-buzplay: BU refactoring, first step
author Mychaela Falconia <falcon@freecalypso.org>
date Sun, 03 Apr 2022 08:11:05 +0000
parents efb93f3e4ac7
children
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efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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1 There is a tiny (120 bytes SREC file) program called flash-boot-wa that was
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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2 written in the spring of 2017 for the purpose of working around a problem that
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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3 happened on only one first-batch FCDEV3B board and never happened on any other
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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4 board - but Murphy's law had it that this one troubled board just had to be the
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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5 one on which my (Mother Mychaela's) very initial development and bring-up work
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Mychaela Falconia <falcon@freecalypso.org>
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6 was done.
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Mychaela Falconia <falcon@freecalypso.org>
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7
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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8 The defect exhibited on that one board was as follows: it had no problem booting
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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9 serially (fc-iram, fc-loadtool, fc-xram) and it had no problem booting from
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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10 flash in mode 0 (see the Flash-boot-modes article in the freecalypso-docs
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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11 repository), but booting from flash in mode 1 (the flash boot mode used by
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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12 FC Magnetite, which is our primary firmware) was troubled. The exact failure
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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13 mode and the root cause were never solved, but the issue most likely involved
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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14 the watchdog reset in some way (it occurs as part of flash boot mode 1 but not
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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15 in mode 0 and not in serial downloading), and because Calypso's FDP output goes
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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16 low during watchdog reset (or at least TI's CAL000 document says so), it is
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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17 plausible that the root cause involved the Spansion flash chip getting unhappy
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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18 as a result of being jerked with extra resets which don't meet its reset timing
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Mychaela Falconia <falcon@freecalypso.org>
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19 requirements.
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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20
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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21 Our new FCDEV3B V2 boards no longer use Calypso's FDP output (it is left
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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22 unconnected) and feature a new flash reset circuit of our own design that meets
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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23 the reset timing requirements of our Spansion flash chip, hence the flash boot
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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24 problem seen on that one FCDEV3B S/N 001 board is not expected to recur on any
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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25 of our current or future boards. However, our little flash-boot-wa program is
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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26 kept around: removing a previously-released 120-byte program for no good reason
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Mychaela Falconia <falcon@freecalypso.org>
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27 is not the way of FOSS.
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Mychaela Falconia <falcon@freecalypso.org>
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28
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Mychaela Falconia <falcon@freecalypso.org>
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29 This flash-boot-wa program is loaded serially via fc-iram; it disables the boot
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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30 ROM and jumps to address 0 (the opposite of what we do in compalstage for Mot
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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31 C1xx phones), thereby indirectly booting the made-for-boot-mode-1 firmware image
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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32 in the flash. The intended usage was as follows:
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Mychaela Falconia <falcon@freecalypso.org>
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33
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Mychaela Falconia <falcon@freecalypso.org>
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34 fc-iram -h fcfam /dev/ttyXXX /opt/freecalypso/target-bin/flash-boot-wa.srec rvinterf
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Mychaela Falconia <falcon@freecalypso.org>
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35
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Mychaela Falconia <falcon@freecalypso.org>
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36 It is also worth noting that fc-iram has been extended to support second program
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Mychaela Falconia <falcon@freecalypso.org>
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37 invokation just like fc-xram (used in the invokation line above) just for this
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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38 peculiar use case. The flash-boot-wa.srec helper can also be booted via
efb93f3e4ac7 doc/Flash-boot-wa: explanatory article added
Mychaela Falconia <falcon@freecalypso.org>
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39 fc-xram.