FreeCalypso > hg > fc-magnetite
changeset 241:63c12cba5ed5
implemented optional workaround for the flash boot problem on FCDEV3B
| author | Mychaela Falconia <falcon@freecalypso.org> |
|---|---|
| date | Tue, 02 May 2017 02:53:36 +0000 |
| parents | 9034c3a7267e |
| children | a6360ee05c47 |
| files | doc/Flash-boot-mode-hack makefile-frags/m0-to-bin-std scripts/flash-boot-mode0.patch |
| diffstat | 3 files changed, 38 insertions(+), 0 deletions(-) [+] |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/doc/Flash-boot-mode-hack Tue May 02 02:53:36 2017 +0000 @@ -0,0 +1,27 @@ +There are two ways in which a flashed firmware image may be booted, which we +call mode 0 and mode 1 - see the Flash-boot-modes write-up in the +freecalypso-tools repository for the details. All TI official firmwares +including our TCS211 reference version have used flash boot mode 1, and the +present Magnetite firmware is unchanged in this regard. + +Some FCDEV3B boards have a non-understood hardware problem that causes flash +boot to fail (the visible symptom is a dead hang with even JTAG not working) +when the firmware image in flash uses boot mode 1. It is not currently known +how many boards are affected by this problem; it is possible that the Mother's +S/N 001 board is the only one that exhibits this oddity. + +Once the discovery was made that the flash boot problem occurs only when the fw +image uses flash boot mode 1, a workaround became apparent: switch to using +flash boot mode 0. Redesigning Magnetite fw to use interrupt and exception +vectors in the ROM branching to 0x80001C-0x800034 in IRAM is not in line with +the Mother's vision, but a surgical hack to make the Magnetite fw flash image +receive control from the boot ROM in mode 0, disable the boot ROM via the +FFFF:FB10 register and jump to 0 as if in mode 1 is quite doable, and it +accomplishes the job of producing a flash image of FC Magnetite that boots +without a hitch on the flash-boot-challenged FCDEV3B. + +The standard FC Magnetite build is unchanged and unaffected, i.e., the hack in +question is NOT applied by default. However, if you have a board that has +trouble booting the regular Magnetite fwimage.bin that uses flash boot mode 1, +you can run 'make fwimage.mode0' in your build directory to get an image patched +with the flash boot mode 0 hack.