PLL & clock settings on GTA02: u-boot vs. qi

Werner Almesberger werner at openmoko.org
Thu Feb 5 13:28:44 CET 2009


scholbert wrote:
> u-boot seems to start at 120MHz and divides FCLK:HCLK:PCLK into 1:2:4 
> while
> qi seems to start at 400MHz and divides FCLK:HCLK:PCLK into 1:3:6

u-boot calls cpu_speed to accelerate from 200MHz to 400MHz in
board/neo1973/gta02/gta02.c:board_late_init

The idea is that u-boot runs with as little power as possible until
it has made sure in wait_for_power that we have enough power to boot.

For Qi, the story is a bit different, because we don't want want Qi
to have to mess with USB and we don't want to sit in Qi anyway. So
the idea is to leave all these decisions to the kernel, as Andy has
explained.

- Werner



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