From mboxrd@z Thu Jan  1 00:00:00 1970
From: Zhukov <zhukov@tst.spb.su>
Date: Thu, 12 Jan 2006 18:42:06 +0300
Subject: Fwd: Re[2]: [U-Boot-Users] at91rm9200 lowlevel_init.S
In-Reply-To: <12601906.20060112170843@tst.spb.su>
References: Your message of "11 Jan 2006 17:24:40 +0300."
 <1136989480.17330.5.camel@localhost.localdomain>
 <20060111154703.4E52835265C@atlas.denx.de> <12601906.20060112170843@tst.spb.su>
Message-ID: <368204843.20060112184206@tst.spb.su>
List-Id: <u-boot.lists.denx.de>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: u-boot@lists.denx.de

>> Does anybody know, what can be tuned in "lowlevel_init" procedure in
>> lowlevel_init.S module for at91rm9200dk? This init suspends u-boot. I

WD> The code is supposed to work fine on the at91rm9200dk board.
WD> Are you really using such a board, or is this some custom hardware?

Yes, my board is customozed - the hardware engineer edited
RomBoot because of some differences in SDRAM system.

But... anyway, the lowlevel_init.S seems so strange, that 
some bug in its code is suspected.

Would you explain the meaning of _MTEXT_BASE in fragments like
this:

        ldr     r0, =SMRDATA1
        ldr     r1, _MTEXT_BASE
        sub     r0, r0, r1
        add     r2, r0, #176
2:
        /* the address */
        ldr     r1, [r0], #4
        /* the value */
        ldr     r3, [r0], #4
        str     r3, [r1]
        cmp     r2, r0
        bne     2b

I guess _MTEXT_BASE is a start of code, the location just after vectors. 
But what's the use of it here?

Suspecting hardware problem, I skip everything after the first step of
the procedure:

        /* Get the CKGR Base Address */
        ldr     r1, =AT91C_BASE_CKGR           
        /* Main oscillator Enable register */
#ifdef CFG_USE_MAIN_OSCILLATOR
        ldr     r0, =0x0000FF01 /* Enable main oscillator */
#else
        ldr     r0, =0x0000FF00 /* Disable main oscillator */
#endif
        str     r0, [r1, #CKGR_MOR]
        ...     /* delay */
        b         exit          

This cut works fine, u-boot loads. Next, I tried to replace this
with the following:

        ldr     r0, =CKGRDATA      
        ldr     r1, _MTEXT_BASE    
        sub     r0, r0, r1         
        add     r2, r0, #8      /* 8 bytes */
3:
        /* the address */
        ldr     r1, [r0], #4
        /* the value */
        ldr     r3, [r0], #4
        str     r3, [r1]
        cmp     r2, r0
        bne     3b
        ...     /* delay */

        ...
        
CKGRDATA:
        .word AT91C_BASE_CKGR
        .word 0x0000FF01
        /* 8 bytes long */

It FAILS! Obviously, u-boot crashes here. Something wrong in code...

Best regards,