- @ Adjust memory timing before lowering CPU clock
- @ Clock speed adjustment without changing memory timing makes
- @ CPU hang in some cases
- ldr r0, =MDREFR
- ldr r1, [r0]
- orr r1, r1, #MDREFR_K1DB2
- str r1, [r0]
+ ldr r6, =MDREFR
+ ldr r4, [r6]
+ orr r4, r4, #MDREFR_K1DB2
+ ldr r5, =PPCR
+
+ @ Pre-load __udelay into the I-cache
+ mov r0, #1
+ bl __udelay
+ mov r0, r0
+
+ @ The following must all exist in a single cache line to
+ @ avoid accessing memory until this sequence is complete,
+ @ otherwise we occasionally hang.
+
+ @ Adjust memory timing before lowering CPU clock
+ str r4, [r6]