[U-Boot-Users] AT91RM9200 Errata (Was: CSB637 support - big bug..)

Anders Larsen alarsen at rea.de
Wed Aug 24 09:42:15 CEST 2005


"Patrick .." <oc3an at gmx.net> schreibt:
>I applied your patches to the 1.1.3 version of U-Boot - they all apply
>fine
>except for the main csb637 patch, which complains about patching a
>Makefile
>and MAKEALL.

Hi,
that's probably due to other boards having been added in the
meantime.

>This is not the main problem however,
>
>In the AT91RM9200 initialisation code, PMC_MCKR is written incorrectly. 
>This register *MUST* be written in two separate steps (see the errata
>sheet
>for the AT91RM9200 for more details).

You're referring to Errata #28, right?
Reading the text it seems you're right; however, this is not
special to the CSB637 board - the code in question
(cpu/arm920t/at91rm9200/lowlevel_init.S) was _not_ touched by
my patch.

>In my case i write 0x201, followed by 0x202.

OK, please provide a patch to lowlevel_init.S then.

>Also, it is safe to use a divisor of 3 for the Master Clock, this gives
>61.44MHz from a core of 184.32Mhz which is fine for the CSB637 (master
>clock
>limit is 80MHz), users should see a decent improvement in performance by
>doing this as it will increase the SDRAM bandwidth by a substantial
>amount.

Well, I got the clock values from linux 2.6.12 board-csb637.c;
does Linux still boot correctly with your change?

Cheers
 Anders

CC'ed to the list, since this is relevant to ALL at91rm9200 users





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