Andreas Schweigstill ha scritto:
Dear Marco!
Marco Cavallini schrieb:
Hi, I am trying to use u-boot-1.1.4 with AT91RM9200 based board. Using Parallel flash all works perfectly, but if I try using u-boot stored in Dataflash i face to some problems and comparing two cases I see that CPU clock are different. Seems that is required a RomBoot provided by Atmel which launch u-boot. Is it really necessary ? Maybe I've miss an option that avoid RomBoot usage ?
You can omit the RomBoot step if you are able to build an U-Boot which fits into ~12KB of the internal SRAM.
RomBoot has to be adopted to your target hardware, especially for CPU clock and memory initialisation. The Atmel provided RomBoot can only be compiled with ARM ADS but there is also a GCC version available:
Andreas thank you for answering. I can't and I don't want to store anything into internal SRAM. I simply want to use Dataflash AT45xxx instead of Parallel AT49xxx
I digged and found that RomBoot leaves the CPU speed at its initial safe state (slow). Clocks: CPU 59 MHz, master 59 MHz, main 18.432 MHz ^^^^^^^^^^
Then I added board_late_init into at91rm9200dk.c and there I've set PLLAR, PLLBR, MCKR like into lowlevel_init.S Now my board boots with the desired clock speed. Clocks: CPU 179 MHz, master 59 MHz, main 18.432 MHz ^^^^^^^^^^
BTW I wonder if could be useful (and appreciated) if I should merge RomBoot settings into u-boot allowing u-boot to be the one and only loader for Dataflash too.
Ciao