annotate doc/C139-notes @ 214:adfdbcd360fd

backlight evolution: API between Condat driver and MFW With this change, the API between the Condat backlight driver and its user in MFW now carries more abstract backlight state codes (fully off, fully on, in call, charging boot mode) instead of 0-255 levels. This change is needed in order to more properly support different hardware targets with different capabilities and approaches in terms of backlight handling.
author Mychaela Falconia <falcon@freecalypso.org>
date Fri, 23 Apr 2021 23:52:02 +0000
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1 FC Tourmaline firmware differs from Magnetite in two principal ways when it
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2 comes to Mot C139 target support:
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3
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4 * C139 LCD support is implemented in a more forward-looking manner: instead of
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5 emulating TI's C-Sample at the lowest R2D driver level and therefore being
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6 forever limited to 84x48 pixel display size, Tourmaline implements a new
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7 96x64 pixel framebuffer, matching the native LCD size of C1xx phones. The UI
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8 configuration is still black&white only though - the Mother of FreeCalypso
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9 has no current plans to support color UI on smaller LCD sizes than TI's
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10 original 176x220 pix.
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11
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12 * Our aftermarket FFS configuration has been changed from 64x3 at 0x3C0000 to
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13 64x7 at 0x300000. Our earlier 64x3 config was chosen back in 2015, at that
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14 time we didn't know how much room we would end up needing for the firmware
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15 image vs. how much FFS content we would eventually have, and this 64x3 config
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16 is now deemed to be too small, allowing only one 64 KiB sector for FFS
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17 content. Our new FC Tourmaline aftermarket FFS config supports up to 320 KiB
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18 of FFS content, matches what we use on other platforms with 4 MiB flash chips,
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19 leaves 3 MiB for the firmware image (our current smallbw UI fw is only 2 MiB),
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20 and still avoids intersection with Motorola's (or rather Compal's) original
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21 FFS, which is important for avoiding problems in converting C139 phones back
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22 and forth between Motorola and FreeCalypso firmwares.