[U-Boot-Users] [ANNOUNCE] u-boot-ptx-20030213-1

Robert Schwebel robert at schwebel.de
Thu Feb 13 22:28:55 CET 2003

On Thu, Feb 13, 2003 at 09:42:51PM +0100, Geir Thomassen wrote:
> in cpu/xscale/start.S you do:
> /* test if we run from flash or RAM - RAM/BDI: don't set cpuspeed   */
> /* FIXME: is the criterium used here only valid for PXA25X?         */
>    mov     r0, pc
>    and     r0, r0, #0xF0000000 /* RAM is at 0xa0000000-0xafffffff */
>    subs    r0, r0, #0xa0000000
>    beq     setspeed_done
>    mov     r0, #2
>    mcr     p14, 0, r0, c6, c0, 0
> setspeed_done:
> Why? I can trace trough the CPU speed setting code without any trouble 
> with a BDI, and I don't understand why there should be any problems 
> doing so. Disabeling the CPU speed setting code without skipping the 
> SDRAM init code at the same time might actually get you into other 
> problems since the refresh periode of the SDRAM might be too long. 
> Jumping over the SDRAM init is a very good idea, since the code is 
> running from the SDRAM that the code is initializing. One important step 
> of the init sequence is to disable the SDRAM.

The code in question was added last week and I removed it today from my
local tree :-) 

The problem is that there is a bug in at least some hardware revisions
of the PXA which in my case lets the debug handler disappear from the
mini instruction cache once you access CP14 to switch the frequency.
I've discussed this with the Abatron guys for some weeks now and they
today have sent me a new firmware which works around the bug. It will be
available officially in some days. However, as I'm now able to run the
code in the debugger again the above code can be forgotten - I will not
send it to Wolfgang officially. 

 Dipl.-Ing. Robert Schwebel | http://www.pengutronix.de
 Pengutronix - Linux Solutions for Science and Industry
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