83xx: Use the proper sequence for updating IMMR.

This ensures that subsequent accesses properly hit the new window.

The dcbi during the NAND loop was accidentally working around this;
it's no longer necessary, as the cache is not enabled.

Reported-by: Suchit Lepcha <Suchit.Lepcha@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>

diff --git a/cpu/mpc83xx/start.S b/cpu/mpc83xx/start.S
index beebc99..26e3106 100644 (file)
--- a/cpu/mpc83xx/start.S
+++ b/cpu/mpc83xx/start.S
@@ -200,9 +200,23 @@ boot_cold: /* time t 3 */
        nop
 boot_warm: /* time t 5 */
        mfmsr   r5                      /* save msr contents    */
+
+       /* 83xx manuals prescribe a specific sequence for updating IMMRBAR. */
+       bl      1f
+1:     mflr    r7
+
        lis     r3, CONFIG_SYS_IMMR@h
        ori     r3, r3, CONFIG_SYS_IMMR@l
+
+       lwz     r6, IMMRBAR(r4)
+       isync
+
        stw     r3, IMMRBAR(r4)
+       lwz     r6, 0(r7)               /* Arbitrary external load */
+       isync
+
+       lwz     r6, IMMRBAR(r3)
+       isync
 
        /* Initialise the E300 processor core           */
        /*------------------------------------------*/
@@ -212,9 +226,7 @@ boot_warm: /* time t 5 */
         * is loaded.  Wait for the rest before branching
         * to another flash page.
         */
-       addi    r7, r3, 0x50b0
-1:     dcbi    0, r7
-       lwz     r6, 0(r7)
+1:     lwz     r6, 0x50b0(r3)
        andi.   r6, r6, 1
        beq     1b
 #endif