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U-Boot for Freescale i.MX5x
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This file contains information for the port of U-Boot to the Freescale
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i.MX5x SoCs.
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1. CONFIGURATION OPTIONS/SETTINGS
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---------------------------------
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1.1 CONFIG_MX51_PLL_ERRATA: Workaround for i.MX51 PLL errata.
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This option should be enabled by all boards using the i.MX51 silicon
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version up until (including) 3.0 running at 800MHz.
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The PLL's in the i.MX51 processor can go out of lock due to a metastable
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condition in an analog flip-flop when used at high frequencies.
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This workaround implements an undocumented feature in the PLL (dither
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mode), which causes the effect of this failure to be much lower (in terms
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of frequency deviation), avoiding system failure, or at least decreasing
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the likelihood of system failure.
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1.2 CONFIG_SYS_MAIN_PWR_ON: Trigger MAIN_PWR_ON upon startup.
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This option should be enabled for boards having a SYS_ON_OFF_CTL signal
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connected to GPIO1[23] and triggering the MAIN_PWR_ON signal like in the
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reference designs.
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2. CONVENTIONS FOR FUSE ASSIGNMENTS
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-----------------------------------
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2.1 MAC Address: It is stored in the words 9 to 14 of fuse bank 1, using the
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natural MAC byte order (i.e. MSB first).
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This is an example how to program an example MAC address 01:23:45:67:89:ab
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into the eFuses. Assure that the programming voltage is available and then
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execute:
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=> fuse prog -y 1 9 01 23 45 67 89 ab
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After programming a MAC address, consider locking the MAC fuses. This is
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done by programming the MAC_ADDR_LOCK fuse, which is bit 4 of word 0 in
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bank 1:
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=> fuse prog -y 1 0 10
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