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39e8576164
The mx5 lowlevel_init.S contains board-specific code based on the reference design. Let's keep it since it avoids creating new lowlevel_init files and it may be used by many boards. But add a config to make it optional in order not to cause issues on boards not following this part of the reference design. Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com> Cc: Stefano Babic <sbabic@denx.de> Cc: Matt Sealey <matt@genesi-usa.com> Acked-by: Stefano Babic <sbabic@denx.de>
23 lines
1.0 KiB
Plaintext
23 lines
1.0 KiB
Plaintext
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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